Ford 300 Inline Six

[CFLBob]

Terry,

What CAM program are you using? Part of Solidworks or does it read their files?


Bob

 

[mayhugh1]

Terry,

What CAM program are you using? Part of Solidworks or does it read their files?


Bob

I'm using Sprutcam which imports native SolidWorks files directly. The version I'm using (SC-7) is some 22 years old now. At the time it was only few hundred dollars and was the most affordable continuous 4 axis CAM programs available. I've used it for all my camshafts. Many have likely never heard of the software. It was a Russian program marketed by Tormach and now by Sprutcam USA. I wrote and put into the public domain the Mach3 lathe post (originally named MyMachTurn) and assisted with the PCNC mill post. I'm told Sprutcam was (is?) widely used in Europe, but it never seemed to catch on in the states. Their badly translated user manual probably had something to do with that. It's the CAM program I learned on, and the only one I've ever used. - Terry

 

[CFLBob]

I'm using Sprutcam which imports native SolidWorks files directly. The version I'm using (SC-7) is some 22 years old now. At the time it was only few hundred dollars and was the most affordable continuous 4 axis CAM programs available. I've used it for all my camshafts. Many have likely never heard of the software. It was a Russian program marketed by Tormach and now by Sprutcam USA. I wrote and put into the public domain the Mach3 lathe post (originally named MyMachTurn) and assisted with the PCNC mill post. I'm told Sprutcam was (is?) widely used in Europe, but it never seemed to catch on in the states. Their badly translated user manual probably had something to do with that. It's the CAM program I learned on, and the only one I've ever used. - Terry

Interesting. I've been having issues with my CAM program, DeskProto, not doing things I'd like it to do. I'm adapting, but there are still some things I don't think it can be convinced to do.

 

[mayhugh1]

Actually, none. I spend the time to get the machine do it as much as possible. I find it best to keep my hands off the parts as much as possible. - Terry

 

[a41capt]

The carburetor and its 'fixins' should be the final parts for this build. George designed a carburetor specifically for this engine, and I wanted to stick to its internals as closely as possible. The recirculating fuel loop I want to use though will require the addition of a fuel bowl.

My fuel loops are complicated by their constant displacement gear pumps which were originally intended to fuel up RC planes. Adding a simple speed control to their drive motor doesn't reduce the flow enough to reliably work in my application. Keeping the bowl filled without overrunning its drain requires the motor to run at a speed too close to zero. In the past I've used a .020" restriction in the pump's output line in order to raise the head pressure and force an internal leak through the pump's gears. This restriction which had to be placed well away from the carb in order to avoid a jet spray inside the bowl, raised the operating point of the motor for a more consistent rpm.

For the Inline 6, I experimented with a more elegant solution - a 'splitter' that returned a portion of the pump's output to the tank before it reached the bowl. The splitter required its own return-to-tank line which I was willing to add if the splitter could have be hidden in the floor of the bowl. It turned out that its performance while so close to the bowl was limited. Building the splitter into its own enclosure well outside the bowl improved things, but I didn't like the extra chunk of hardware. The splitter really belongs inside the fuel tank, but I was long past redesigning the tank. In the end, I went back to using a restrictor.

Some experimenting was also needed to optimize the shape and size of the fuel bowl. A tiny bowl with a pressurized inlet, negative pressure outlet, and gravity fed drain provides some challenges. The drain tube height inside the bowl establishes its steady-state fuel level which I want to be 1/8" below the spray bar. But, unless an accounting is made for surface tension across the drain's input, the actual level can be very different and inconsistently high. Another issue is that a maelstrom can be generated between a tiny bowl's inlet and drain, and this can affect fuel flow to the needle valve.

After a week or so, I had a tested bowl design that I was happy with, and I began the design of the carb body. The bowl was integrated into a body that used George's internals as well as the existing mounting pad on the intake manifold. The mount proved particularly troublesome, and the carb's installation will require some heroic effort with a tiny crowfoot fashioned from a 5/32" open end wrench.

Machining of the carb body began with a block of aluminum squared up to body's outside finished dimensions. Its six faces were carefully machined in as many setups. Despite two power brown-outs during machining and a couple operator errors that forced some design changes along the way, I was able to continually rescue the original workpiece and finally hold the finished carb body in my hands. The body was bead blasted, dipped in NaOH, and then alodine'd for a poor man's gold iridite like appearance.

The carb body was a fun side project that included a few 'firsts' for me. I don't think I've before put so much machining into such a small chunk of metal. I only recently discovered SolidWork's Text functionality, and I used it instead of my CAM software to add the engraving to the front of the carb. Another 'first' was the waterline machining operation using a 1/32" end mill that it required. Now, it's on to the 'fixins'. - Terry

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That’s beautiful Terry! I love the Holley logo as well. Damn Brother, truly amazing work!!!

John W

 

[burkLane]

I'm using Sprutcam which imports native SolidWorks files directly. The version I'm using (SC-7) is some 22 years old now. At the time it was only few hundred dollars and was the most affordable continuous 4 axis CAM programs available. I've used it for all my camshafts. Many have likely never heard of the software. It was a Russian program marketed by Tormach and now by Sprutcam USA. I wrote and put into the public domain the Mach3 lathe post (originally named MyMachTurn) and assisted with the PCNC mill post. I'm told Sprutcam was (is?) widely used in Europe, but it never seemed to catch on in the states. Their badly translated user manual probably had something to do with that. It's the CAM program I learned on, and the only one I've ever used. - Terry

Your name is still listed and shown when compiling g-code as one of the authors on the pcnc mill Sprutcam post to this day.

 

[mikehinz]

The carburetor and its 'fixins' should be the final parts for this build. George designed a carburetor specifically for this engine, and I wanted to stick to its internals as closely as possible. The recirculating fuel loop I want to use though will require the addition of a fuel bowl.

My fuel loops are complicated by their constant displacement gear pumps which were originally intended to fuel up RC planes. Adding a simple speed control to their drive motor doesn't reduce the flow enough to reliably work in my application. Keeping the bowl filled without overrunning its drain requires the motor to run at a speed too close to zero. In the past I've used a .020" restriction in the pump's output line in order to raise the head pressure and force an internal leak through the pump's gears. This restriction which had to be placed well away from the carb in order to avoid a jet spray inside the bowl, raised the operating point of the motor for a more consistent rpm.

For the Inline 6, I experimented with a more elegant solution - a 'splitter' that returned a portion of the pump's output to the tank before it reached the bowl. The splitter required its own return-to-tank line which I was willing to add if the splitter could have be hidden in the floor of the bowl. It turned out that its performance while so close to the bowl was limited. Building the splitter into its own enclosure well outside the bowl improved things, but I didn't like the extra chunk of hardware. The splitter really belongs inside the fuel tank, but I was long past redesigning the tank. In the end, I went back to using a restrictor.

Some experimenting was also needed to optimize the shape and size of the fuel bowl. A tiny bowl with a pressurized inlet, negative pressure outlet, and gravity fed drain provides some challenges. The drain tube height inside the bowl establishes its steady-state fuel level which I want to be 1/8" below the spray bar. But, unless an accounting is made for surface tension across the drain's input, the actual level can be very different and inconsistently high. Another issue is that a maelstrom can be generated between a tiny bowl's inlet and drain, and this can affect fuel flow to the needle valve.

After a week or so, I had a tested bowl design that I was happy with, and I began the design of the carb body. The bowl was integrated into a body that used George's internals as well as the existing mounting pad on the intake manifold. The mount proved particularly troublesome, and the carb's installation will require some heroic effort with a tiny crowfoot fashioned from a 5/32" open end wrench.

Machining of the carb body began with a block of aluminum squared up to body's outside finished dimensions. Its six faces were carefully machined in as many setups. Despite two power brown-outs during machining and a couple operator errors that forced some design changes along the way, I was able to continually rescue the original workpiece and finally hold the finished carb body in my hands. The body was bead blasted, dipped in NaOH, and then alodine'd for a poor man's gold iridite like appearance.

The carb body was a fun side project that included a few 'firsts' for me. I don't think I've before put so much machining into such a small chunk of metal. I only recently discovered SolidWork's Text functionality, and I used it instead of my CAM software to add the engraving to the front of the carb. Another 'first' was the waterline machining operation using a 1/32" end mill that it required. Now, it's on to the 'fixins'. - Terry

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Hi, may I ask exactly what material you're bead or sand blasting with? Also what sort of blasting gun are you using? Your results are outstanding!

Mike

 

[mayhugh1]

Hi, may I ask exactly what material you're bead or sand blasting with? Also what sort of blasting gun are you using? Your results are outstanding!

Mike

I bought the cabinet back in the mid-90's from, I think, Eastwood. I remember purchasing a spare nozzle at the same time, as I thought they might wear out quickly, but I'm still running with the original one. The glass bead media I use was purchased from the local Harbor Freight at the same time. I know you can buy different grades of glass media, but I'm not sure what this one is. It's whatever Harbor Freight was importing at the time, and I can tell you it's seen a lot of use since then. - Terry

 

[mayhugh1]

A bowl gasket and heat insulator mounting block were machined while waiting for the delivery of an 8-80 tap and die set. Model engine carb adjustments are traditionally sensitive especially when using gasoline. Every cold start seems to require some re-tweaking regardless of how well the engine was running when last shut down. I've often wondered is this might be caused by a bit of corrosion between the dissimilar metals in the needle and spray bar. In any event, adjusting the Ford's needle valve with an air cleaner assembly in place will be awkward, and so I thought (without thinking) an ultra fine pitch thread might make things a little easier. I nearly always cut external threads on my lathe, but the 8-80 was too intimidating and I went with the 'simpler' die.

An 8-80 thread is rare, and I wasn't able to find an on-line chart with dimensional data nor any help in the gun/knife forums. Using the tap was pretty straightforward, but I had a lot of difficulty with the die. Coming up with a close-fitting thread half inch thread pair was unexpectedly difficult and very sensitive to the die's spreader screw. The initial quarter inch of the male threads was the problem. Even with the die supported in the lathe's tailstock die holder, useable results required a very light touch while getting the threads started and a minimal grip on the die holder during the rest of the threading process. I practiced on a half dozen test parts after ruining half as many spray bar bodies before I had a workable technique.

The final spray bar body with its .040" diameter spray bar and .020" orifice was machined from 12L14 using very sharp tools, lots of patience, and some re-tweaking of my lathe's tailstock. Aluminum proved to be too soft and gummy, but I was able to make a part in bearing bronze. Another unexpected difficulty involved center drilling the .020" orifice with a sensitive drill holder. Imperfections in every center-drill I owned left a microscopic center nub that prevented the tiny drill from starting on the part's exact center. I was eventually able to get a clean start using a 1/8" 60 degree carbide v-cutter.

A sewing needle was epoxied in the bronze needle holder that was tapped with the less troublesome 8-80 female threads. A Delrin bushing inserted inside the spray bar holder keeps the needle centered at the entrance to the spray bar orifice. A Delrin collar located between the the spray bar holder and the needle assembly prevents damage when the needle is fully closed.

Two throttle assemblies with integrally machined Venturi's were made - one from bearing bronze and one from Delrin. Delrin's natural lubricity allowed a snug fit without a lot of cantilevered weight hanging from the carb body. Both the throttle and needle assemblies were made long enough to allow access from beneath a three inch air cleaner assembly.

The bowl was filled with fuel, and a low pressure air stream directed through the Venturi over a paper towel. Under wide open throttle, the resulting spray pattern showed at least three full turns between full OFF and full ON.

Mounting the carb on the engine proved every bit as difficult as I expected. It eventually required the temporary removal of both the throttle assembly and the needle valve in order to set the nuts on the manifold mounting studs. After tightening down the carb and before coming up with an air cleaner assembly, I decided to test start the engine. The tank was filled with gasoline and the engine spun up using my clutched drill starter made earlier.

The engine startled me when it immediately took off and ran, but it died before I got my fingers on the needle valve. Something didn't feel right when I tried to restart it, and I soon realized the flywheel was slipping on the crankshaft. After removing the bell housing I could see that the key that was supposed to secure the flywheel to the crankshaft had either sheared or worked its way up into the companion slot in the flywheel. I hadn't noticed before, but the broached slot in the flywheel seems much too deep in comparison with the depth of the machined slot in the crankshaft. I used standard hardened/ground 1/16" key stock, and so I won't know what really happened until I get the flywheel off. The two are now stuck fast together and will require machining a custom puller to separate them. Craaaaap! - Terry

 

[propclock]

Wow That is a bummer. Hope it works out well in the future.
8-80 , I thought 1/4 80 was tough enough All my hope for a happy ending.

 

[gbritnell]

Hi Terry
It's hard to believe the key moved out of place but it's certainly missing from the picture. I can't wait to hear your engine run!

 

[mayhugh1]

With a stack of wood shims under the oil pan, the bell housing was removed so I could work on the rear of the engine. The flywheel was stuck fast on the crankshaft and without provisions made for jackscrews to remove it, a shop-made puller was needed to separate them. The reason for its enormous arms was to simplify the machining needed to get a strong enough pair of fingers through the .040" gap between the flywheel's o.d. and the bell housing mount. The size of that gap was arbitrarily chosen, and I'm glad it wasn't even smaller.

The damage, although significant, was confined to the last quarter inch of the rear of the crankshaft. A short and embarrassing explanation of what happened is that the slot in the flywheel was much too deep for the key.

The broach used on the flywheel was from an ancient Enco boxed assortment that included pieces of square key stock. With the end of the crankshaft previously milled with a .035" deep slot to accept half of a 1/16" square key, I assumed the broach would cut a similar slot in the flywheel. In reality, it was designed to cut a full 1/16" deep slot.

The slot actually wound up a bit shallow at the rear end of the flywheel thanks to its sloppy bushing, and this was enough to lock the flywheel to the crankshaft until it was put under load. With the end of the key deep inside the flywheel's long rear snout, the error wasn't obvious during assembly.

Even worse however, I wondered where else I might have made the same mistake. The next day was spent going over the notes and photographs of all my other builds. It was mostly serendipity, but the only other place where I seem to have pulled the same trick was in the timing pulley on the other end of the Ford's crankshaft. Since it's negligibly loaded, I can wait until there's a reason to pull the radiator before addressing it.

The damage to the crankshaft increased its clearance inside the rear third of the flywheel by a couple thousandths which would have added unacceptable wobble. The problem was almost totally eliminated with a centering bushing that replaced the existing flywheel retainer and effectively extended the length of the crankshaft.

I also deepened the crank's .035" slot using the maligned broach which I modified for use as a scraper. I planned to deepen the existing slot to .070", but after a couple hours I stopped at .045" since the slot had veered off course from the crank's centerline and could introduce a new problem. A one-off key was ground from tool steel with the final result being a snug-fitting wobble-free flywheel that was safely secured to the crankshaft.

I'd been looking forward to starting on the air cleaner assembly to top off the engine and hide the unsightly throttle and needle valve. But with the engine running, it was difficult to not at least address its extremely smokey exhaust. This is the first engine I've built that doesn't use an oil pump and instead relies upon 'splash' lubrication which in is affected by the level of oil in the sump.

I don't believe it's necessary for the rods or crank webs in a closed crankcase multi-cylinder engine to dip into the crankcase oil. The back-and-forth air pumping between cylinders will create an oil storm inside the crankcase that will keep all its internals wet. In a full-size engine this windage is a power-robbing nuisance. In an essentially unloaded model engine it can be used to advantage to supply enough lubrication to control wear without overcoming the typical oil controls machined into model pistons.

I found the best way to add oil to this engine is through the dipstick port using a hypodermic needle. I began with 45cc of 10W-30 which was enough to wet the ends of the connecting rods when at their lowest positions. A rendered cross-section of the crankcase shows the three levels I tried. The 45cc's smoked like crazy and spit lots of oil out the exhaust. The highly aerated oil was drained and replaced with 35cc. With this amount the connecting rods were just barely above the oil, and the results were nearly acceptable but not yet suitable for indoor running. Reducing the oil level to 20cc cleaned up the exhaust entirely with only light smoke puffs during acceleration. I'll likely try 25cc at the next oil change.

Currently, the engine starts easily and idles at what seems to be a very low rpm. It's been rev'd up a few times, but after the flywheel incident we still have trust issues between us to overcome. The needle and air bleed haven't yet been optimized, and I'm still running with my initial 5 degrees BTDC timing. The engine's shakedown and fine tuning will continue, and I'll post a video when the air cleaner is finished. - Terry

 

[gbritnell]

Hi Terry,
I'm glad to hear that the flywheel key fiasco didn't result in major damage. I run my engine at about 15 degrees of advance. This is the old hot rudders seat of the pants timing method. Advance until it runs the best then back off a touch.
gbritnell

 

[Basil]

Another awesome build Terry. I would have been sweating with how much pressure would have been required to pull the flywheel off and wondering how badly the assembly might have galled. Top job!

 

[ShopShoe]

When you first posted about this setback I was really sorry to hear it.

However, I am amazed at your analysis of the cause of the problem and the ingenious solutions you came up with.

As always, your builds are awesome and I learn so much from them, even if my humble projects don't even approach what you can do.

Thank You for posting "Warts and All,"

--ShopShoe

 

[a41capt]

Nice recovery Terry. Glad it worked out so well, I worried that your crankshaft received irreparable damage, but knowing your ingenuity, I figured you’d already have a plan!

John W

 

[mayhugh1]

Fine tuning was simpler than expected. With the engine rev'd up as high as I was comfortable with, the needle valve was adjusted for a peak. Although the tuning was a bit broader than I'm accustomed to, I'm not sure it was worth the hassle I ran into with the needle's 8-80 threads. The engine idles nicely at the same needle setting which was surprising since I expected to have to fiddle with the air bleed screw. The position of the screw in the air bleed hole doesn't seem to have much effect, but leakage around it through the air bleed hole might be. The constant fuel level presented to the carburetor's spray bar by the recirculating loop tends to add consistency to the tuning.

The radiator warms up after a two minute run which means coolant does circulate - probably with a lot of help from thermal siphoning. I haven't yet run into any hot start problems, but that may change when the air cleaner assembly is added. Hot exhaust manifold air trapped below the air cleaner could help or hurt performance. I may take some IR photos later.

Since the flywheel is enclosed by the bell housing, and the front of the engine is blocked by the radiator, there isn't a convenient was to measure rpm with either an optical or mechanical tach. In hindsight, a tach output integrated into the CDI's front-end board would have been nice to have. Later, I'll likely couple a scope to the distributor's tower wire in order to get a measurement of the engine's rpm range.

So far, the engine is free of oil and coolant leaks. The well-sealed crankcase was a bonus and allows control of the crankcase gasses which will be vented through the rocker cover as they were in the full-size engine. A piece of tissue held over the filler cap hole is visibly affected by the crankcase pressure pulses. The oil mist that's dragged along with those gasses will tend to fill the volume under the rocker cover and provide lubrication for the roller rocker top-end. Since the primary path into the rocker cover is through the oil drain holes located behind the side-mounted tappet cover, the lifters will be wetted as well. The filler cap I machined is very similar to the one that was on my '72 truck engine.

I'd been looking forward to the air cleaner assembly because it would be an interesting machining challenge and something I'd not done before. Along with the bell housing, it turned out to be one of my favorite parts of this build. I don't plan to run an air filter, but the housing will add realism and reinforce the stock appearance of the engine. A major goal for the housing's design was to lower the apparent height of the carburetor whose bowl turned out be larger than I wanted. Its weirdly long throttle and needle valve were in anticipation of a 3" diameter air cleaner assembly that will set down over them.

The three piece air cleaner assembly includes a baseplate, cover, and an air intake snout. Since the assembly will end up virtually sealed to the top of the carburetor, the snout was made functional. It's through-hole was plunge cut with a 3/8" end mill and the end openings worked with needle files. Minimum weight was a key consideration for the whole assembly since the carburetor it mounts to is held onto the intake manifold with only a pair of 2-56 studs. All the material that was removed from the baseplate gives it's interior something of an unexpected appearance.

The cover was machined on the mill although it could have more easily done on the lathe. My final post will include photos of the completed engine and a video of it running. - Terry

 

[a41capt]

Love it! Looks like it just came out of my old Ford F100!!!

John W

 

[propclock]

AbFab as always you are an inspiration. Super happy the crank keyway
issue was resolved. Again thanks for all your efforts posting and lessons learned.

 

[ddmckee54]

You're going to make a filter element for it aren't you?

I mean you went to all the trouble of making that FINE looking air cleaner, you're going to make it functional - right? Maybe a cut-up foam lawn-mower filter element? You want to get 100,000 miles out of that engine it's got to breathe clean air.

The return to tank line looks awfully close to the exhaust down-pipe, any concerns about the heat affecting the fuel lines? (Maybe there's more clearance than the picture makes it appear to have?)

Don