# 1/3 Scale Ford 289 Hi-Po



## mayhugh1 (Oct 16, 2022)

My shop time this past summer was spent modeling a Ford 289 Hi-Po engine. Its five main castings include the block, a pair of heads, the intake manifold, and a timing cover. Using workshop manuals and online photos for reference, I set out to build a 1/3 scale model of the popular 60's era muscle car engine.

A precise assembly of these five complex parts is a must, but the sources I was using left me with plenty of blanks to fill in. After a frustrating month of endless design and re-design, George Britnell graciously offered me his SolidWorks models of a nearly identical full-size 302 engine. He used these in another thread on this forum to 3-d print a quarter scale version of the same engine. It's fair to say that without his help my own project would have died on the vine.

SolidWorks has a powerful tool that's capable of scaling an entire finished model, and this is just what's required for 3-d printing. George's printer resolution allowed him to retain the rich detail in the engine's original castings, and he was able to print a museum quality model. Trying to replicate his results in metal on my Tormach however would require tiny and impractically long cutters and numerous setups with unreasonable machining times (or George's skill with a Dremel tool). So, I made modifications to the full-size engine's design to create a set of machining-friendly scaled models that retain much of the look and feel of the original engine.

Unfortunately, SolidWorks' scaling function doesn't scale the underlying sketches that make up the model. This means that design changes on the scaled model have to be made through the full-size version before it's scaled. With the complex filleting in the original castings creating the majority of the machining headaches, bouncing back and forth between the two models became insanely difficult. So, I decided to start again and created yet another set of 1/3 scale models based upon George's originals.

My models for the block, heads, intake manifold, timing cover, crankshaft, and camshaft are nearly complete. I have a running virtual assembly that includes rods, lifters, and pushrods and a camshaft driven from the crankshaft through a sprocketed timing chain as well as a distributor driveshaft driven from the camshaft through a custom helical gear set. What isn't yet complete is a block oiling scheme although the distributor has been angled around the crankshaft for a distributor-driven oil pump that matches what was done in the full-size engine .

During modeling, partial tool paths were generated using my CAM software so I could test the aging software and computer resources against the models' complexity. The block's lifter valley and the top surfaces of the intake manifold will likely tax my ability to generate the high resolution tool paths that I like to use.

The intake manifold's internal fuel and coolant passages need more work, and all the models will receive minor tweaks along the way. I've developed a bad case of computer burn-out, and I need to start making chips to keep up my enthusiasm for this project.

Material for the major workpieces has been rounded up. The engine will be machined from 7075 aluminum which is a considerably harder alloy than 6061 and capable of durable bearing surfaces and superior finishes. A 3" x 6" x 72" chunk of this was purchased 25 years ago from a building demolition site for just $35. It's now back inside my shop and being sawed into workpieces.
































Before anyone asks, I'll gladly share what documentation I end up with after the engine is finished. Please don't ask me for George's original models since they're not mine to share. - Terry


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## GreenTwin (Oct 16, 2022)

Nice 3D modeling work.

Quite a challenging engine to build, so say the least.

I think the power of 3D modeling shines when you get into complex designs like this.

.


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## mayhugh1 (Oct 25, 2022)

At 1/3 scale, most of the modified filleting can be safely machined using quarter inch ball cutters. As a bonus, those little nuisance parts should be a little easier to handle compared with those in a typical quarter scale model. I just wish I'd thought ahead about the dimensions of my raw stock. The finished height of my modeled block is 3.000", but the raw stock for its workpiece was only 2.970" high.
The first step in preparing the block's workpiece was to machine the .625" camshaft bore completely through my sawed off chunk of 7075. A gage pin in this bore will be used later to reference all the block's machining operations. The bore was located and spot-drilled on the mill before being indicated and drilled in my lathe's four-jaw chuck. An eight inch deep 7/16" through-hole was pre-drilled using a long Guhring drill followed by a 19/32" aircraft drill. The bore was finished using a .625" reamer supported in a floating tailstock holder. While still in the lathe, the front surface of the workpiece was faced normal to the hole's axis.

Surface plate measurements revealed the hole's entry point was within .002" of its target, but its exit on the axis already lacking stock was off by .010". A length of 5/8" drill rod was lightly polished for a close sliding fit in the bore and used to square up the other five sides of the blank to within a thousandth or so of the camshaft's axis. This, of course, removed even more stock from the already short axis.

A pair of blind 7-1/2" deep quarter inch holes drilled on either side of the camshaft bore with an aircraft drill completed the block's workpiece. These non-critical holes will eventually connect the coolant jackets on each bank to the outputs of the water pump. They were drilled using a combination of my mill's quill and bed feed since my lathe didn't have enough swing to handle the offset needed in its 4-jaw.

Before re-tweaking the block's design to fit within the finished dimensions of the workpiece, I wanted to verify the modeled spacing between the cam and crank bores. I came up with this spacing using an online roller chain calculator for a 12/24 tooth sprocket pair and 37 links of 3/16" pitch chain. The sprockets were machined from 1144 so I could verify their spacing. I wouldn't normally make these parts so early in the build, but with an untested block design it was necessary for peace of mind. This in turn required finalizing the camshaft's mounting details.

The cam's front and rear ends will be supported by 3/4" o.d. sealed ball bearings, while its three inner bearings will just run inside the block material. The cam sprocket will attach to a pinned flange on the nose of the camshaft through three slotted holes that provide the adjustment for timing the valves to the crankshaft. While back in SolidWorks a few cosmetic details were added to the lower end of the block including freeze plugs, engine mounts, and an oil filter mount. Provisions for a dipstick and a faux fuel pump are still needed, and I'm also considering an electric starter.

After machining the sprockets, their spacing was measured with a simple fixture on my mill. It was then I discovered my rookie mistake. A closed loop roller chain can only have an even number of links and I had designed for an odd number. After studying my alternatives, I decided to stay with the current sprockets and reduce the spacing for 36 links. This sounds like minor re-work, but it severely broke my model which will now require days of rework. On the bright side, it was better to find my mistake now, and hey it looks like the block's going to fit inside the workpiece after all. - Terry


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## Scott_M (Oct 25, 2022)

Hi Terry
Looking good !
Was there a reason you don't want to use a 1/2 link ?        1/2 link at Mcmaster Carr


Scott


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## mayhugh1 (Oct 25, 2022)

Scott_M said:


> Hi Terry
> Looking good !
> Was there a reason you don't want to use a 1/2 link ?        1/2 link at Mcmaster Carr
> 
> ...


Scott,
Thanks much for your reply. To be honest I wasn't even aware of half links. After reading your response, I went searching but couldn't locate any for 3/16" pitch chain. This chain which I found on eBay several years ago being sold for repairing a particular pocket bike engine isn't at all common. Many online roller chain calculators don't even recognize its existence. - Terry


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## Scott_M (Oct 25, 2022)

Hi Terry
 I saw this and thought wow that is big chain for a model It must be much bigger than I think.
Little did I know it was a typo. But that explains it  


mayhugh1 said:


> 37 links of 5/16" pitch chain.



Is it already re-3D modeled for the shorter chain ?

Scott


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## Scott_M (Oct 25, 2022)

I found plenty of #25 ( 1/4" pitch )  But nothing smaller  

Scott


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## mayhugh1 (Oct 25, 2022)

Scott_M said:


> I found plenty of #25 ( 1/4" pitch )  But nothing smaller


Scott,
You're right it was a typo. I corrected it to read 3/16". - Thanks - Terry


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## ozzie46 (Oct 25, 2022)

Here we go. Got my popcorn and chair.

Ron


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## gadabout (Oct 25, 2022)

I just googled and came up with a normal link and a offset link for 5mm chain which they also marked as 3/16” next to it


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## rpf (Oct 26, 2022)

Looks like these people do 0.1875" & 0.1475 pitch roller chains, Micro Pitch Chain from KATAYAMA CHAIN | MISUMI


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## Eccentric (Oct 26, 2022)

Yeeeaaaa!  Terry is back making chips!  It's like Netflix releasing a new season of my favorite show.


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## dnalot (Oct 26, 2022)

I like to watch

Mark T


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## sition (Oct 26, 2022)

nice


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## johnmcc69 (Oct 26, 2022)

Fantastic work! Beautiful model & machining!
 -Great memories as well! I rebuilt a 289 for a 1968 Mustang coupe I once had, great little engine.

 What exactly were the differences in the "standard" 289 & the "Hi-PO" version? If I remember correctly (which I don't some most times..), it was just a change in the head design combustion chambers & a larger pulley driving the alternator. 

 Were there changes to the block as well?

 John


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## mayhugh1 (Oct 26, 2022)

johnmcc69 said:


> Fantastic work! Beautiful model & machining!
> -Great memories as well! I rebuilt a 289 for a 1968 Mustang coupe I once had, great little engine.
> 
> What exactly were the differences in the "standard" 289 & the "Hi-PO" version? If I remember correctly (which I don't some most times..), it was just a change in the head design combustion chambers & a larger pulley driving the alternator.
> ...


The intake manifold was also a high rise - something that will be an add-on in my model to save machining time. The air cleaners on the ones I've seen were also chromed cold air types. - Terry


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## johnmcc69 (Oct 26, 2022)

mayhugh1 said:


> The intake manifold was also a high rise - something that will be an add-on in my model to save machining time. The air cleaners on the ones I've seen were also chromed cold air types. - Terry



 Was the "Hi-Po" a single plane manifold as well?

 You know you're going to have to do the Cobra air cleaner & valve covers right? 

 John


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## a41capt (Oct 29, 2022)

And we’re off and running on another terrific season of “What fantastic creation will Terry make next?”  I’m already addicted to this season’s episodes!!!

Thanks Terry,
John W


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## Ghosty (Oct 29, 2022)

Another serial to watch, Thanks Terry.
Cheers
Andrew
PS did the ford straight 6 get lonely


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## mayhugh1 (Nov 2, 2022)

The changes needed to correct the timing gear spacing involved only the block and timing cover. I decided to not trim the bottom of the block to maintain the 50/50 crankshaft split I had across the block and oil pan after realizing the front and rear oil seal inserts will fill the pan gaps nicely.

In preparation for the block's bottom end machining, the main bearing scheme was finalized. In what will be a deviation from the original engine's design, sealed ball bearings will be used at the front and rear of the block, and the three center bearings will be bronze disks. I used this mains setup on my last two engines and it worked well. Although the three bronze bearings will require fitting, I'll be able to avoid a line boring operation and scraping five clamshell bearings. This scheme works well, and the oil pan hides the blasphemy. A downside is that the ball bearings will complicate the routing from the oil pump.

With its numerous angled surfaces, the block's machining will require many setups. I started with the easy bottom surface which required only a work-holding vise. The deep pockets between the block's webs were designed for 3/8" cutters to avoid the chatter that would have come from the long skinny cutters needed for a precisely scaled interior.

One of the photos shows the heart-breaking result of the block's very first roughing pass. The operation wound up offset from the camshaft axis by .200". I traced the error back to a surface plate measurement where I'd misread a '9' as a '7' on my height gage. Several weeks ago, the close-up vision difficulties I've been having in the shop were diagnosed as cataract related. Corrective surgery is scheduled in a few weeks, but until then a magnifying glass and flashlight have become my best friends.

After a few days of mourning, a new workpiece was prepared. This one was finish machined with zero excess stock on all surfaces in order to minimize the number of hands-on measurements I'll need to make before my surgery. The pucker factor was high while the operation was rerun, but the last photo shows my do-over landed in the right place. This build has had a rough beginning, and my confidence is in some serious need of rebuilding. - Terry


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## Eccentric (Nov 2, 2022)

Terry,

All the best during your eye surgery! It will be awesome to be able to see clearly afterwards.  Many of us are in the same boat, I need ALOT of light to do most things now. No worries about the scrapped block, it could have come much later in its machining. And I noticed you had a nice long stick of 7075 for another go.  (Pretty precious stuff)

take care, Greg


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## mayhugh1 (Nov 5, 2022)

The three pairs of 6-32 threaded holes that will be used to attach the inner bronze bearings to the block were machined by counter boring, spotting, drilling, and then tapping with a spindle tap holder. These bolt holes need to be carefully located to insure the bearings will repeatably install during fitting.

An extended reach 3/8" ball cutter was used to finish the interior surfaces (excluding those for the bearings). This step probably wasn't necessary since the interior will be hidden by the oil pan, but I'll be looking at it for the next several months. Measurements of the finished webs were used to determine the effective cutting diameter of the end mill which turned out to be a surprising .373". This diameter was used by the CAM software to compile the tool paths for the bearing pockets which were machined in their own operation. The final result was a pair of close-fitting ball bearings.

I was anxious to verify the final sprocket spacing. When I corrected the block design I did so for minimum chain slack based upon measurements using the actual parts rather than the 'sloppy' spacing recommended by my chain calculator. The fit was essentially identical to my target.

The next operation was to machine the bell housing mounting flange on the rear end of the block. This operation's peripheral machining was extended some half inch below the flange in order to produce reference surfaces for the cylinder decks when they're machined later. (The front end machining will be extended similarly.) An additional .010" deck material was added to the CAM model used for this operation to create extra stock for the decks' finishing passes. The pocket for the rear cam bearing was machined in its own operation using the cutter's effective diameter determined from measurements of the finished flange. The result was a light press fit for the ball bearing. - Terry


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## dnalot (Nov 5, 2022)

mayhugh1 said:


> close-up vision difficulties I've been having in the shop were diagnosed as cataract related


I have had the surgery to install artificial lenses in both eyes. Painless and life changing. I expected to be able to see better but what really blew me away was the vibrant colors. Old eyes have yellowed lenses that make everything thing drab looking. If your getting new lenses you will be thrilled with the outcome. It's just a little unnerving seeing the knife coming at you end on. Don't blink.

Mark T


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## mayhugh1 (Nov 12, 2022)

The block's front end was machined similarly to its rear end leaving .010" excess deck material for indicating and later finishing. I'm not sure why I drilled that pair of 7" deep 1/4" diameter coolant holes through the front of the first (scrapped) block. They only needed to be deep enough to penetrate the cooling jackets of the two front cylinders. Since the jackets overlap between cylinders, coolant will flow through the block without those deep holes.

The block's front-end features were roughed-in using 3/8"and 1/4" end mills before being finished with an extended reach 1/4" ball cutter. Most of the front-end's modeling time was spent adapting the full-size engine's filleting to this particular cutter. The organic cavities between the camshaft and distributor bores ended up with fillets stacked upon fillets, and the whole thing was a house of cards ready to fall with any changes to the design. It was this area that drove my decision to correct the timing sprocket error by moving the crankshaft up rather than the camshaft down. Since the fuel pump and dipstick will be later add-ons, the front-end machining is essentially completed.

The original workpiece was carefully machined so its surfaces could be used to indicate the block within its various machining setups. As the workpiece is machined away, work-holding and indicating become more difficult. To fix this, a fixture plate was machined next. It bolts onto the bottom of the block through the oil pan holes and is dowelled to it.

An angle table will be used for the 45 degree and 225 degree setups. The fixture plate will be required in the two 45 degree deck milling operations. The block will have to be flipped over for the two side milling operations which require the 225 degree setups. To keep the setups rigid, the block will be clamped to the angle table with a bar run through the crank bearing webs. On the surface plate this bar indicated true to within a thousandth on all block axes.

The Enco angle table I own is rigid enough, but precision is sorely lacking. Its most frustrating issue is the ground slots which aren't parallel with the table's rotational axis. This error which is nearly .050" at 45 degrees varies with the tilt angle, and changes when clamped down to the mill table. I typically re-machine a portion of the table every time I use it, but this only makes things worse for the next setup.

For this build, the table's 45 degree tilt was indicated on a surface plate using the deck reference surfaces machined on the block's front and rear ends. Custom tee-nuts were machined to allow the workpiece to be shimmed into alignment. Of course, when moved to the mill, all this will have to be re-tweaked.

I'm still working up a machining sequence to make best use of the workpiece during the remaining operations. - Terry


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## mayhugh1 (Nov 19, 2022)

The left and right sides of the block laying between the already finished front and rear surfaces were machined next. Both sides hold bosses for the motor mounts as well as cosmetic freeze plugs, and the driver's side includes a mount for a spin-on oil filter. The most efficient machining orientations were +/- 225 degrees, and so the top surface of the workpiece was mounted against the 45 degree angle table. It was clamped in place using the crankshaft test bar laid through the crank bearings. The bar was indicated and used to reference the workpiece to the mill.

CAM software differentiates between a "part" and its "workpiece" and creates tool paths which remove material from the 'workpiece' until only the 'part' remains. The part is usually defined in CAD, while the CAM software provides a default workpiece or maybe a user defined one based upon a combination of boxes, cylinders, and tubes. The prismatic workpieces presented by the sides were pretty inefficient compared with the default CAM options. Fortunately, my software allows the workpiece to also be created in CAD. This was my first experience with this feature, and although a four hour learning curve was involved, it saved nearly two hours of 'air machining' time. Total machining time for the two sides was some ten hours.

The sides' filleted features were designed to be finished with a 1/4" ball cutter, but a one inch long 1/8" end mill was needed to cleanup the flat areas between a couple closely spaced fillets. The block's reflective surfaces not only make photography difficult, but minor surface defects are tough to see. The eighth inch cutter left some chatter in the surface finish that will have to wait to be cleaned up until after the block is bead blasted to a satin finish.

I recently junked my Trico micro-drop coolant dispensers and replaced them with Fog Busters. The proprietary Trico hoses are ridiculously expensive and require yearly replacement. My coolant of choice for machining aluminum is WD-40, and it worked well in the Trico units, but I could not get the Fog Busters to reliably flow it. I tried every combination of air pressure and unit mounting height and even magnetically stirred the reservoir, but the flow rate knob had to be continuously tweaked while running.

I'm now using Kool Mist which flows well in the Fog Busters, but the sticky surfaces left behind on my machines and tooling is taking some getting used to. Another thing I've noticed on 7075 is splotchy staining that's reminiscent of silver tarnish. It was particularly noticeable on the workpiece surface that was clamped against the cast iron angle table. There's no apparent surface damage, but white Scotch Brite isn't quite abrasive enough to remove it. - Terry


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## gbritnell (Nov 20, 2022)

Wonderful work Terry! Are you keeping any kind of log on the hours?  This of course would include design time. Although I never included oil galleries in part models I could send you a layout of them if you like.


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## mayhugh1 (Nov 21, 2022)

gbritnell said:


> Wonderful work Terry! Are you keeping any kind of log on the hours?  This of course would include design time. Although I never included oil galleries in part models I could send you a layout of them if you like.


George,
I never tracked the hours spent on design, but I have kept tabs on some of the machining times. Yes, I'd like to see your oil passage sketches and could also use your water pump model. Right now, I'm recovering from surgery on my right eye, and everything is pretty blurry. Hopefully that's temporary. - Terry


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## brotherbear (Nov 21, 2022)

mayhugh1 said:


> George,
> I never tracked the hours spent on design, but I have kept tabs on some of the machining times. Yes, I'd like to see your oil passage sketches and also use your water pump model. Right now, I'm recovering from surgery on my right eye, and everything is pretty blurry. Hopefully that's temporary. - Terry


Best wishes for a positive and speedy recovery from both of your eye surgeries, Terry!!


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## e.picler (Nov 22, 2022)

Congratulations Terry!
Again another extraordinary project. 
I wish you have a prompt recovery from your eye problem.

What cutting speed and RPM do you use on your Waterline strategies machining? I use the same CAM as you.

Edi


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## mayhugh1 (Nov 22, 2022)

Ed,
Thanks. For roughing with a 3/8" flat cutter I use 5000 rpm at 20 ipm. For roughing or finishing with a 1/4" flat cutter I use 5000 rpm at 15 ipm. For finishing with a 1/4" ball cutter I use 5000 rpm at 15 ipm and a scallop height of .0003". - Terry

edit ... I should add that I'm using 4 flute cutters.


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## mayhugh1 (Nov 22, 2022)

Workpiece material covering the deck surfaces was faced to within .010" of their finished values in order to improve machining access to the lifter valley. The remaining material will be removed later when the cylinder liners are installed.

I'd been looking forward to the lifter valley machining ever since my modeling-palooza last summer. It soaked up lots of hours of effort, and after several frustrating do-overs I finally had something I could live with. Thanks to my constraint that it had to be machinable with a quarter inch ball cutter, I wound up with yet another amateurish and fragile design that wouldn't tolerate even minor design changes.

Shortly after finishing its CAD, I learned through a correspondence with George that the lifter bores aren't parallel to the cylinder bores as I had assumed. Instead, there's some 3.5 degrees difference between them. Correcting the lifter bosses would have required starting over again. The error didn't sound significant, and so I decided to continue on with what I had. Later, when more of the engine's modeling was complete and I had a virtual assembly, I discovered the lifter angles had been necessary to avoid conflicts between the push rods and rocker arms. My workaround will be to angle the bores in the existing bosses by two degrees and make up the difference with modifications to the heads.

The lifter valley's total machined surface is now probably the most complex thing I've ever machined, and I was relieved when it was finally done. The finishing pass was over 150K blocks of g-code, and for some reason crashed Mach3 with a mysterious 'emergency shutdown detected' error every time it was loaded under my Tormach profile. I still don't understand why since my computer indicated nearly half of its three gigabytes was still available after the code was loaded. Dividing the operation into two half-size overlapping operations seemed to solve the problem though. Somehow it seems a shame to hide that seven hours of machining under the intake manifold.

One of the last steps in the lifter valley machining was to spot drill shallow divots in the tops of the lifter bosses that will used as sanity checks when the angle table is readjusted and the lifter bores drilled. This won't happen for a while though. I just had my first eye surgery, and it looks like it will be several days before its vision returns. - Terry


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## solarenergyadventures (Nov 23, 2022)

Wow! Just Wow!


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## johnmcc69 (Nov 23, 2022)

Very nice! That must have been "Fun" to model it up. 

 A shaky finger on the "Cycle start" button?

 Wishing you a speedy recovery!

 John


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## e.picler (Nov 24, 2022)

mayhugh1 said:


> Thanks. For roughing with a 3/8" flat cutter I use 5000 rpm at 20 ipm. For roughing or finishing with a 1/4" flat cutter I use 5000 rpm at 15 ipm. For finishing with a 1/4" ball cutter I use 5000 rpm at 15 ipm and a scallop height of .0003". - Terry


Hi Terry! Thanks for your information. What is the "Scallop Height" My SprutCam is in Portuguese.

Thanks,
Edi


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## mayhugh1 (Nov 24, 2022)

e.picler said:


> Hi Terry! Thanks for your information. What is the "Scallop Height" My SprutCam is in Portuguese.
> 
> Thanks,
> Edi


On the parameters page of the water line operation there is an option for setting the scallop height. When you select this, the software will compute the machining levels of the operation's toolpaths so a 'ridge' no higher than what specified by the 'scallop height' is left in the surface finish. This is an alternative to just specifying the distance between steps which one would likely do for a waterline roughing operation. Setting this height to a tiny value will produce a smooth and shiny surface with a waterline finishing operation. Of course, the disadvantage is a longer machining time. Depending upon the slope angle of the features to be mavhined, .001" can produce a nice finish especially if the surface will be bead blasted. I don't know why I chose .0003". I guess I was trying to see how far I could push things, but more likely I was just showing off >) - Terry


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## Basil (Nov 27, 2022)

Hi Terry
I'm working on my big block Chevy program. I would like to know your opinion on flat plane verses cross plane cranks on these engines. I am mainly concerned with the finished sound of the engine as I am sure most of us want to also replicate this. The full size units definitely do sound more like a  V8 with a traditional cross plane. What was your plan on the 289? Thanks


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## mayhugh1 (Nov 28, 2022)

Basil,
I expect that a manifold that keeps the flow rate up as high as possible would be best in a model engine. I plan on using a single plane manifold though to keep the machining reasonable. I've found the things that affect the engine's sound the most to be the camshaft and the exhaust pipes. Opening up the exhaust valves early can have a significant effect on the loudness. - Terry


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## Basil (Nov 28, 2022)

Sorry Terry, we appear to be at crossplanes, lol.
 I was referring to the crankshaft configuration.
 Cheers


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## mayhugh1 (Nov 28, 2022)

Basil said:


> Sorry Terry, we appear to be at crossplanes, lol.
> I was referring to the crankshaft configuration.
> Cheers


I apologize.  I could barely make out your post. A week after my right eye surgery I'm still essentially blind in that eye except for a bright glare that affects my total vision. Reading is such a hassle that I've become a couch potato in front if the tv. Needless to say progress on the 289 has come to a halt.

To answer your actual question, though, I'll be using a cross plane crank, but I don't know enough about the two types to intelligently comment on your question. Regards. - Terry


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## Basil (Nov 29, 2022)

Hi Terry, So sorry you are struggling after your eye surgery. I wish you a speedy recovery. Many thanks for your reply.


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## DiegoVV (Nov 30, 2022)

I hope the best for the master


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## mayhugh1 (Nov 30, 2022)

Basil said:


> Hi Terry, So sorry you are struggling after your eye surgery. I wish you a speedy recovery. Many thanks for your reply.


Well, it turns out that I've lost 90% of the vision in my right eye after the surgery. I thought cataract surgery was pretty much routine, but evidently it isn't always. The doctor agrees something is wrong but she isn't yet sure what went wrong. The autorefractor that tested the lens in my eye seems to likes it even less than I do, but it just gives up testing with no hint about why. I go back next week for a consultation but without knowing what the problem is, I'm not sure what the next step will be.

I've restarted work on the block to get my mind off all this. I found that if I cover up my right eye, I can see enough through my left to work for short periods without the nausea. - Terry


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## michael-au (Nov 30, 2022)

Hope your next report is a positive one
You do amazing work


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## nj111 (Dec 1, 2022)

Wishing you all the very best for a positive outcome.  Thank you again so much for sharing your amazing craftmanship, I have learnt so much from your builds. Nick


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## Basil (Dec 1, 2022)

Yes, I think I can speak for most everyone here in that we all look forward to seeing an engine progress report from Terry. Always top notch!
Hang in there and get well rested! Very much praying you eyesight improves soon.


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## mayhugh1 (Dec 7, 2022)

So far, my eye doctor hasn't been specific about what went wrong with my cataract surgery. It's a good thing that protocol is to do only one eye at a time, but I was expecting a lot more for the extra $3K spent for a 'premium' lens. An appointment was scheduled for earlier this week, but she's out for a week with her own personal emergency and hopefully OK. I hoped resuming work on the engine might help with my current depression, but this is a tough hobby for someone with bum eyesight.

I eventually recalled why I'd planned to drill that pair of 1/4" coolant distribution holes through the cylinder banks even though the water jackets around each liner would be interconnected. They were intended to feed coolant from the jackets to the heads through vertically drilled transfer holes located safely away from the edges of the head gasket. The cooling scheme inside the head isn't fully worked out yet, and with so little space for effective coolant flow, replacing metal around the combustion chambers with passages that might entrap air or stagnant coolant might not be a smart move. In any event, the 1/4" thru-passages were drilled, but the transfer holes will be drilled later.

The cylinder bores were machined next. With the block mounted to its fixture plate and setup on the 45 degree angle table, the bores were started with 5/8" pilot holes. The bores themselves were interpolated on my Tormach using a long reach 1/2" diameter end mill. Although the x and y axis backlashes on my machine have been .0005" and .00075" respectively for the last dozen years, the worst circularity error measured just over two tenths. Before machining the bores, the cutting parameters were tuned during a few practice runs on the first block's carcass.

The integral water jackets were designed to hold just under a cubic inch of coolant around each liner, and they were machined using a key seat cutter. To obtain this volume, a 1-1/4" diameter cutter that barely cleared the bore's entrance had to be used. Its 3/16" thickness, though, proved to be 2x too much for chatter control.

My CAM software refuses to create tool paths when a portion of the part overhangs the cutting zone. Tricking it into working by lying about the part required care and manual g-code changes to the cutter's lead-in and lead-out to avoid what would have been a spectacular crash. The code was designed around a single cylinder and tuned using practice runs on the scrapped block before being run eight times on the real thing.

The large diameter 3/16" thick cutter was a bell waiting to ring. It screamed during the entire full thickness passes at the top of each bore regardless of parameter tuning. Flooding those top level passes with WD-40 took some of the edge off the incredibly loud noise, but the first three minutes of each operation were pretty scary and had not only my full attention but also my hand on the emergency stop. Once the full thickness passes at the top of a bore completed, the half-thickness passes below it were much better behaved and the surface finishes surprisingly nice.

The tappet bores were drilled/reamed next. As mentioned earlier, their axes are tilted slightly toward the centerline of the engine to present the correct pushrod geometry to the rocker arms. The two degrees that I used may not sound like much, but it will make a significant difference at the tips of the pushrods.

The final operation was to be the bore for the distributor. It's currently a deep and angled multi-diameter interrupted cut that I over-designed without enough thought about how it will be machined. I need some time to reconsider its design and to make a few practice runs before risking the nearly finished block.- Terry


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## mayhugh1 (Dec 11, 2022)

Although I don't remember the distributor in my old Mustang's 289 not sitting vertical, a ten degree tilt was needed to move its axis away from the crankshaft so it can drive an oil pump. The distributor itself will be driven by the camshaft through a custom 1:1 helical gear set. In order to fit within the available space, a shop-made fractional DP cutter will be needed to machine these gears. Since I had to do something similar for the inline six in my last build, I should be a little ahead of the learning curve.

The bore for the distributor is complicated by its multi-diameter requirements and the deep interrupted cuts created by the features around the camshaft bore. A SolidWorks rendering shows the bore's cross section. The distributor shaft is supported by a pair of ball bearings inside the distributor, but when modeling I added a third bearing just below the helical gear. Its purpose was to help stabilize the distributor and to ease insertion of the oil pump driveshaft into the pump.

All this looked good on paper but seemed like something that should be mocked up before adding it to the nearly finished block. For practice I machined a duplicate set of block front end features around the camshaft bore on the scrapped block (in fact, they were added to both ends). The bottom line result of my testing was that the third bearing was probably a good idea.

The pair of bores that locate the top and bottom ends of the distributor body to the block were roughed in with plunged end mills and finished using boring heads. Since I had two boring heads, I left their practice settings untouched for use on the block and was very surprised when the block's bore diameters ended up some .005" undersize. The discrepancies turned out to be due to rpm differences created by a last minute decision to bore the block using the mill's back gear. The rpm had become important due to tool deflections in the interrupted cuts. Returning to the original practice rpms eliminated the differences.

A final issue arose when machining the 3/8" pocket for the bottom bearing. A press-fit in this hard to reach location would have created bearing servicing problems. Even though the floor of the pocket had been designed with a tiny breakout for a shop-made removal tool, I made a last minute decision to change to a close slip fit. All my 3/8" end mills cut 373"- .374" diameters even when extended as far as possible in a collet, and the deflection of a tiny long reach boring tool would have added too much uncertainty. My final solution was to chuck a 3/8" end mill in one of my dollar store drill chucks and take advantage of its runout. By adjusting the stick-out I was able to dial in the pocket diameter for a near perfect fit. One of the photos shows the dummy distributor parts used to mock up the distributor assembly in the finished block. Measurements showed the center-to-center gear spacing to be within a couple thousandths of my target.

I wouldn't normally machine the distributor hold down bracket this early in the build, but its tiny size and ten degree mounting base made it one of those pita parts that I just wanted to be done with. It was machined from an odd piece of aluminum temporarily epoxied to a block of MDF and wasn't as problematic as I had expected. Working from its bottom surface, the entire part was machined in a single setup. Its sloped mounting surface was machined using a ball cutter and tiny waterline steps.

This essentially completed the block's machining except for a pressurized oiling system that will be revisited later. - Terry


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## mayhugh1 (Dec 18, 2022)

With the model for the timing cover seemingly in good shape, it was machined next. Its rear face will bolt up to the front of the block through a Teflon gasket, and the water pump which hasn't been designed yet will bolt to it's front face through a second gasket. The timing chain and distributor gears will lie behind the cover, and the crankshaft will spin in a fluoroelastomer seal. The full-size cover has an integral mount for the fuel pump on the driver's side, but the scaled mount will be a bolt-on for a cosmetic pump. On the passenger side is the tube for a functional dipstick.

Clearances for the timing components on the rear face of the cover were machined first. Its more interesting front face retains most of the features on the full-size cover and was machined next. Machining the two faces left the semi-finished cover still attached to its workpiece through a partial framework of excess stock. Quickset epoxy was used to safely secure the finished part to the top half of the workpiece while it was machined free from the bottom half. An hour at 300F cleanly released the part from the remnants of its workpiece.

Due to its small features I wasn't able to come up with a realistic looking cover that could be finish machined with a 1/4" ball cutter as I did with the block. Its shallow features, however, allowed the use of practical length 1/8" and 1/16" cutters although at the expense of machining time. The cover's twelve hour machining time was spread over several days.

Only after finishing its machining did I notice the lower half of the raised mounting boss for the water pump lacked a similar number of mounting screws to its upper half. An online search for photos of the original Ford timing covers showed they were similar. Although I wouldn't give a second thought to using sealer on a full-size engine, I try to avoid its use on models. So, I drilled and tapped two additional holes along the lower portion of the mounting boss. Although these particular screws will lie outside the gasket, they should help it seal.

The mount for the faux fuel pump was machined from a separate block of aluminum and bolted to the side of the cover with a hidden pair of 2-56 screws. The dipstick tube is a length of 5/32" stainless tubing whose exact length and shape will be determined later after the location of its upper mounting bracket on the head is determined. A 2-56 grub screw in the rear of the cover secures the tube's bottom end. Finally, the timing cover gasket was cut from .010" Teflon sheet using a vinyl cutter on my Tormach.

The cover was bead blasted in preparation for later painting, and the block will eventually receive the same treatment. In order to save some block machining time, I used some rather coarse waterline steps on a couple of its features that I now regret. They'll need to be filed/polished out before bead blasting, but my vision is now so poor that I can barely see them. And, the doctor who did my cataract surgery doesn't know why. She's hoping the problem will go away on its own in the next several weeks, but I'm not so optimistic.

The model for the heads needs a little more work, but I think the heads will likely be the next parts I'll try to work on. - Terry


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## dsage (Dec 19, 2022)

Amazing work Terry. I'm glad you are able to soldier on. We all appreciate it and are in awe of your work.


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## e.picler (Dec 22, 2022)

Hi Terry!
Amasing work! 
One more wonderful project.
Did you recover from you eye problem?

Tks,
Edi


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## mayhugh1 (Jan 3, 2023)

Even though the cylinder banks are staggered, the left and right heads are identical. Some but not all of the asymmetry in the assembled engine will be visually absorbed by the block and intake manifold.

Since the vision in my right eye still hasn't returned after cataract surgery, I've not spent much time in the shop lately and instead made another pass at the head modeling. In particular, I wanted to reduce the insane number machining setups I'd allowed to creep into its design.

The Hi-Po engines used roller rockers mounted on individual studs. The valve train components aren't yet designed, and so rough equivalents were used to verify the top-end geometry. The stud mount locations were finalized with a 1.6 rocker arm ratio and clearances between the valve train components and the valve covers. The current design includes bronze valve cages which will allow pretesting the valve seats independently of the finished heads.

During our recent arctic freeze the shop was warmed up for some low-risk chip making while creating workpieces for the heads. Even though the head design was still evolving, its envelope was locked in some time ago by the finished block. The workpieces were sawed from the same piece of 7075 from which the block was taken. Using a rather sketchy setup, the cross-cuts for the heads were also sawed length-wise to make blanks for the valve covers. The head workpieces were then squared up identically and with .015" excess stock on each face.

The purpose of the excess stock was to allow the workpieces to be re-squared around the 3/16" coolant through-holes that were going to be drilled on the lathe. Instead, they were drilled half depth from either end on the mill using a 134 degree Guhring drill. The ends of the coolant passages were tapped so they could be blocked off with screw-in 'freeze plugs'. 

There are lots of advantages to having identical heads, but I found myself confusing the workpiece orientations until they received some unambiguous machined features. The transfer passages connecting the coolant through-holes to the mounting faces of the block and intake manifold became these features and were drilled next. The coolant return paths through the intake manifold still have to be worked out. - Terry


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## minh-thanh (Jan 4, 2023)

mayhugh1 said:


> View attachment 143058
> View attachment 143067
> View attachment 143068
> View attachment 143069


 
   You always make everything perfect !


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## peterl95124 (Jan 4, 2023)

very much enjoy watching your impeccable work.

my own experience with the type of drill you used for your coolant passages
is that they are too flexible (the chip grooves are ground too deep), so I use
extra long drills with normally ground grooves and lots of pecking to clear the
chips.  Also I shimmed the part in the vise so that a dial-indicator in the quill
showed that the part was perfectly parallel to the quill before starting  (which
went spotting drill, stub length drill, jobber length drill, extra long drill, then
flip the part over and do it all over again from the other end,  also I always fill the
hole with tapping fluid while drilling, just in case !, especially if doing the drilling
after having already invested a lot of time machining the part ).


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## mayhugh1 (Jan 4, 2023)

peterl95124 said:


> very much enjoy watching your impeccable work.
> 
> my own experience with the type of drill you used for your coolant passages
> is that they are too flexible (the chip grooves are ground too deep), so I use
> ...


Peter,
I agree with your comments about small diameter Guhring drill flexibility and more importantly about the need for a plumb set up. I once had an 1/8" diameter 6" deep Guhring hole go off course even though it had been started with a stubby drill. In this case, 3/16" seemed to work well on its own with lots of WD-40 and 1/4" pecks. You can tell early on by the sound the drill on its way back into the hole during pecking if you're in trouble. - Terry


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## mayhugh1 (Yesterday at 2:36 PM)

As it turned out, I wasn't able to significantly reduce the number of setups needed to machine the heads. Each one requires 62 drilled holes, and nearly all of them at odd angles to the faces of the workpiece. Their precise angles and entry/exit points through the heads' surfaces are critical for proper mating to the block and manifolds not to mention the need to navigate through the coolant passages. Many of these holes were inherited from the block and manifold models via a SolidWorks assembly (think of them as having been virtually transfer drilled), and so they didn't come with their own standalone dimensions.

In addition, the setups needed to drill most of the heads' holes aren't going to be the same as those used to machine its surfaces. So, I decided to pre-drill them all while the workpiece was still square and easy to work-hold.

The first step was to drill (undersize) the through-holes for the head bolts and temporarily tap them for attaching to a dowelled fixture plate. The dimensions of the rest of the holes were then derived with respect to the faces of the workpiece and the drilling accomplished with the help of an angle table. Since the corners of the workpieces had been carefully finished so they could be unambiguously indicated with a spindle microscope, tooling balls weren't needed. One of the photos shows a typical setup on my crappy imported angle table. That isn't a parallax error in the bottom t-slot. The rest have been re-milled parallel, but the bottom one was left as it was received and custom t-slot stops slid along it to fine tune workpiece alignments.

Since work-holding wouldn't be affected, the combustion chambers were machined before going on with the rest of the drilling. They're a lot of work for a typical model engine, but I was impatient to see them. Except for their equal-sized intake and exhaust valves, the model's wedged chambers are very similar to those used in the full-size engine. Their very prominent un-shrouded spark plugs should perform well in a model.

The pushrod guide/clearance holes required an angle of 88 degrees, the valve cage bores and rocker stud mounting holes an angle of 70 degrees, and the intake manifold mounting holes and counterbores an angle of 45 degrees. The exhaust ports and flange mounting holes required a 60 degree setup and so a pair of 90 degree 3" angle plates were prepared to support the dowelled fixture plate on the angle table. The intake ports required a 15 degree setup on a across-wise mounted angle table.

The drilling was completed except for the spark plug holes which in my infinite wisdom currently require a compound angled setup. These holes require drilling, threading, and counterboring for a seat all of which must be done in the same setup. There's little margin inside the combustion chambers to handle mis-drilling, and so some more more thought is going to be needed.

I'm scheduled for surgery in two weeks to repair the damage done to my right eye during my cataract surgery. Hopefully, my vision will improve shortly after that. For the past seven weeks, it's been measure once, measure twice, measure three times, measure four times, drop the highest and lowest, average out what's left, cross fingers, and then drill. - Terry


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## johnmcc69 (Today at 4:34 PM)

I can't say enough about how much I Like your set-ups, very well thought out, the kind of thing that keeps you up at night.

 Great work!

 John


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## AllenS (Today at 7:29 PM)

Scott_M said:


> I found plenty of #25 ( 1/4" pitch )  But nothing smaller
> 
> Scott


You might check Tamiya. The used to build an RC motorcycle that used something like 1/8" pitch for the final drive. Was very small and i have seen that there are several rd motorcycles still being built


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