Miniature Tunnel Ram on Demon V8

[raveney]

In the video it appears you are revving it up by adjusting voltage? ?

I have a question on this also

Thank you for noting that. Yes I am revving the engine with a voltage supply. It will start and run okay on a 6V battery, but lacks crisp throttle response. I want to remedy that, and have several theories and solutions. I am hoping to hear your and/or other expert's input.

The distributor has a 8 hole aluminum disc with 8 rare earth magnets equally spaced at the circumference passing over a hall sensor affixed to the body of the distributor housing. The signal triggers a Jerry Howell TIM-6 circuit board that I soldered together from a kit.

Full disclosure: I am a slow learner at all things electronic.

In troubleshooting this issue, I attempted to run on a 6V 7AH lead acid battery which it starts and runs happily on up to about 3200 RPM. It stumbles after that no matter where I rotate or time the distributor to. The 6V ATV coil was purchased from the Howell site also.
I tried running it off my 12V lawn tractor battery and promptly smoked one or both transistors. The diode and resisters were fine. Replaced the components and it worked again the same way.

My guess is that I do not have the magnet disc phased correctly with the rotor, so I am contemplating refabricating or modifying the distributor housing to allow adjustment. I like the rule: "If you can't make it right, make it adjustable"

I contemplated making another rotor and affixing the brass strip again precisely following Steve's instructions in the plans. I overthought this step during the build because of perceived backlash in my homemade bevel gears on the cam to distributer shaft.

It could also be a carburetor issue, but I feel that the variable voltage improving the throttle response is a clue. By increasing the electrical potential, it may be bridging the out of phase rotor tip to wire contacts? They all appear to be clean except for the coil one which blackens up after running several times.

Perhaps a spring brass part or graphite brush could be made small enough to fit here also.....

Any thoughts would be extremely welcome.
Russ

 

[raveney]

Hello,
The next parts to be made were the cylinder heads. A rigid and adjustable means of supporting these parts in the various angles was needed, so an aluminum table was made based on a terrific video by Mr. Pragmatic Lee on YouTube.

The pivot is 2" round aluminum and may be clamped in the mill vise for light duty, or clamped to the table slots as shown. It is easy to make and fairly repeatable if one sweeps the parallels with an indicator. It also proved useful later for the intake.

 

[raveney]

Hello again,
The next few weekends were pretty tedious as I had anticipated making valvetrain parts. I opted to wind my own springs using an online calculator here:
https://www.cgtk.co.uk/metalwork/calculators/springValve material was SS 303, and machined it 0.100 at a time while pulling out of a collet chuck. Followed up by using a shop made external lap to final tolerance.

 

[raveney]

Hello,
The camshaft was made on a 7x14 lathe using a jig and dial that was in the plans. A cutting chart gave depth of cut based on relative indexing of the camshaft blank. A standard grooving tool with carbide tip was long enough to use. I used Dykem to mark the lobes at each step and followed the chart 5 degrees each step. Only a little bit of filing and emery cloth at the end gave very satisfactory results. I had never made a billet cam before and thought this was a brilliant idea by Steve.
Russ

 

[raveney]

Hello again,
I wanted to move on to fabricating the crankshaft, but didn't have the stress-proof material on hand. I started the distributer and made a plug cutting tool for the plug towers. I made four attempts using black Delrin, Bakelite, Micarta and finally some Teflon looking white plastic. The Delrin was glued up to achieve the thickness and fell apart. The Bakelite machined great, but the towers fractured when pressing the brass contacts in. The Micarta was too tough and dulled my tooling. The white plastic ended up being the best. I didn't have the resources to order black Teflon, so I painted it. Later on I removed the paint, as it chipped off in places.

 

[raveney]

Hello,
The project veered down a rabbit hole when it came to gears. I personally enjoy tool making as much as making the project, and decided to make all the gears for this engine rather than purchase them. I have used simple shop-made gear hobs on the rotary table, but the tooth profile seemed too sharp in my opinion and cumulative error when indexing multiple passes is probably why on my sketchy rotary table and mill. Ivan Law authored a terrific book that is still in print here for less than $15. It provides several options on different techniques to be successful.
https://www.amazon.com/Gears-Gear-C...93-9118-2cfb6c6a10dc&pd_rd_i=0852429118&psc=1
I chose the eccentric disc type, and needed 4 cutters for the different gears due to number of teeth. Only thing I had to purchase was a flat of O-1 tool steel, which I also used to make a replacement wood plane blade.

One starts by making button cutters for each size disc. I made double ended ones to economize the setups and material. Also made a wooden box, which required a table sled for the box joints, and a hinge jig for making brass hinges. See where this is going....?

Anyway, the gear tooling cost far less than commercial sets if one doesn't put a price on labor which I don't.

 

[raveney]

Hello,

All gearing was machined using brass blanks. The spur gears only need a single pass of the cutter at fairly low speed (300 RPM). Bevel gears need 3 passes; indexing the blank differently for each pass creating the triangular tooth profile. Ivan Law provides excellent instruction in a chapter just for bevel gears. I set up the camshaft in the mill vice and used the fine adjustment on the quill to determine the height of the distributor shim. I ended up cross drilling the bevel gear to distributer shaft with a hardened pin later on, as the tiny #2 grub screw would loosen when running the engine. This makes distributer disassembly more difficult because one cannot access the rotor to shaft set screw.

Another thing I did differently was to use an old morse taper dead center and attach it to a chuck backing plate that accepted my 4 jaw chuck. The thought was that I would turn the blank in the lathe, remove the chuck/taper and reinstall in the rotary table. This should eliminate some concentricity error, and allow swapping back to the lathe to debur the teeth. Looked good on paper, but in reality I think that the amount of stick out from both the headstock and table increased deflection. In the end, it's a compromise. Probably need to replace the spindle bearings in my little lathe. One might be able to see some error in depth of cut on the larger cam gear in picture 4.

Russ

 

[raveney]

Hello,
Thank you all for the interest and likes. The multi-plane crankshaft was a first attempt for me. I had completed several flat plane crankshafts using the fabricated method on steam, hot air and four cylinder IC engines. I researched a lot and used the approach documented by the Black Widow V8 creators documented in Model Engine Builder Issue #30.
First off the crank sleeves were made to support the OD as journal material was removed. I used scrap 1" sch 80 carbon steel seamless pipe.

A special parting tool bit was made by carefully grinding a HSS blank. A Deckel tool grinder would be nice for this, but I made do with the grinder and dremel. This reduces chatter significantly.

Also note the drive fixture that is in the four jaw chuck. It has two centers that fit the center drilled holes in the crankshaft ends to repeatedly remove and reinstall the blank so one can remove material in the mill, change position of support sleeves and swap ends. I set travel stops to reduce the possibility of a crash.

The machined flats near the ends are just there to properly index the crankshaft blank, so I can center drill the ends. I lack the Z height on my mill, and had to rig up something in the drill press.

The finished crank came out nice. There was some ovality on the rod journals that had to be fine tuned and resulted in varied dimensions of the finished OD. This was compensated by making matched rod bearings for each journal. The crankshaft took me nearly 5 days to complete, so I didn't risk getting fancy with shaping the counterweights.

Question for the group: Does anyone have an idea of how many Demon V8s have been successfully completed?

Russ

 

[petertha]

Very interesting. So the crank sleeve fixture is intended to be clamped either side of the journal being cut to keep the others aligned? Is this an alternative to other methods I see where spacer blocks are temporarily attached in between the webs as the turning progresses. What material is the crankshaft?

 

[raveney]

What material is the crankshaft?

Thank you for the questions!
Plans called for stress relieved 1144 carbon steel to minimize distortion. I purchased a 12" long round bar at Online metals for approximately $12 at the time. The magazine article called for 4340 steel which is stronger, but that engine had forced oiling so their crankshaft was cross drilled for oil passages. The more common 1144 worked great for me.

Is this an alternative to other methods I see where spacer blocks are temporarily attached in between the webs as the turning progresses.

This method of clamping is intended to minimize deflection when turning the off center planes between centers. The limitation of course is the counterweights must be round.

Very interesting. So the crank sleeve fixture is intended to be clamped either side of the journal being cut to keep the others aligned?

Yes. One must make several length pieces. I started at the centers and worked outwards

I would like to share the full article, but I believe it is copyrighted/protected.

 

[raveney]

Hello again,
Production parts next are pistons, rods, rings and rod bearings. The rods were made entirely on a rotary table to achieve the taper and radius on small end. They have small tabs intended to scoop up oil with a small passage through the bearing as this is a splash oiling system. I later discovered that too high of an oil level in the pan will flood the cylinder walls resulting in smoke. They are all identical, but stamped them due to bearing sizes and future differences in wear after disassembly.

Pistons were sized, grooved and counterbored on lathe, then parted off moved to mill for small end pocket. Back to lathe to face the top, and then back to mill to drill and ream the wrist pin holes. Made a fixture that fit the pocket to index the wrist pin hole based on other peoples advice.

Next I soft soldered two pieces of bronze bearing material and using a four jaw chuck in the lathe, made individual bearings for each rod. The journal size was fairly consistent, but the side thicknesses varied. I made them oversized widths and carefully fit them by using wet/dry abrasive on a surface plate.

The piston rings were made using gray cast iron and the method recommended on the plans. I machined them, split them, filed ends and sanded to thickness on the surface table. The piston grooves are supposed to be 0.020 inch and was made using an exacto blade carefully clamped in a shopmade tool holder. Very very little stickout. Measuring the groove width with a feeler gauge showed that the grooves were undersized 0.001 to 0.002 so the rings ended up being tighter than they should be and not sealing correctly. I made lots of spares and that helped later on.

After the first few runs, I disassembled the engine and evaluated the rings and cylinders (also the valves and seats) and re honed the block and replaced rings that had cracked (2) and were sticking (3). The compression was tested using a brake bleeder type vacuum pump

 

[Bentwings]

ive made tools out of band saw blades bu not exactly , I’ll have to temper that one .
Thank you for the questions!
Plans called for stress relieved 1144 carbon steel to minimize distortion. I purchased a 12" long round bar at Online metals for approximately $12 at the time. The magazine article called for 4340 steel which is stronger, but that engine had forced oiling so their crankshaft was cross drilled for oil passages. The more common 1144 worked great for me.



This method of clamping is intended to minimize deflection when turning the off center planes between centers. The limitation of course is the counterweights must be round.



Yes. One must make several length pieces. I started at the centers and worked outwards

I would like to share the full article, but I believe it is copyrighted/protected.

 

[raveney]

I wanted to attempt something different for the intake. Really liked the idea of a supercharger such as Steve has plans for, but after studying his build log decided it was outside my skill level making the lobes functional. I learned of a process called lost foam casting on Youtube University, and set my hopes on a tunnel ram with dual carburetors.
A youtuber named Kelly has a site here:
http://forums.thehomefoundry.org/index.php?forums/lost-foam-casting.14/Kelly has a lot of informative videos where he replicates TransAm racing parts for 60s-70s Ford engines.

First I built a hot wire cutting table to control dimensions. The concept is to use a transformer and dimmer switch to control low voltage current thru Nichrome wire held in tension. I have been successful replicating thin sections of 0.100 this way to use as a valley pan for the intake.

Then I had lot's of fun mocking up several prototypes to get the proportions just right.

The foam is high density foam board used to insulate block walls here in Florida. It is glued up with low temperature glue sticks, and filleted using plumbers toilet bowl wax. I had two good ones that I then dipped in a thinned drywall mud mixture cut with dishsoap. The soap makes the foam and wax less hydrophobic. The plaster mix keeps sand out of the casting and improves surface finish. The pattern is placed in regular sifted sand (no clay) and shaken using a sawzall. The first pour is shown below, and one can see that my pouring basin floated and ended with a molten puddle of aluminum on top of the sand instead in the pattern

I had anticipated several attempts, and had a backup at the ready while the forge was hot. The next pour, I used a funnel made from metallic duct tape instead of the pouring basin. The website calls it a kush cup. This time it was successful. I really enjoyed this type of casting in place of greensand. I have no idea how successful it would have been attempting to pull a wooden pattern with cores in this scale.

The casting ended up shorter than I planned lengthwise, but was able to make it work. Look at the front edge. It machined up nicely, and was able to open the ports using a burr bit and drills. It was cast solid.

 

[raveney]

Some lessons learned in this post;

The next parts made are valve covers, water pump, thermostat housing, fuel delivery. I didn't capture a lot of machining setups during this part of the build.
I used a 12 Volt power supply and vinegar/salt water to Nickle plate some small parts during this time. Later on I plated the headers previously shown.

Had a mishap while plunge cutting the cavities in one valve cover. The part was inverted in the vise, and the end mill grabbed and pulled the part up resulting in a unintended see through/cutaway engine feature. I think a piece of paper between the part and jaw would have prevented this.

I also learned that when the small sacrificial piece of Nickle starts to get smaller, do not use any wire between the alligator clip and the material to suspend it deeper in the solute. The wire will become the cathode or anode. So I now realize that one can copper plate and stainless plate using this mistake.

One more silly thing that I did. On the linkage connecting the carburetors I used a 0.094 small bit of scrap drill rod as a shaft. I also used this part to hold the bell-crank levers while I soldered them. Later in the project, I wanted to cross drill these and pin onto the shaft. Guess what happens when you attempt to drill through 0-1 steel after it has been heated and cooled? Yep, It's rock hard and small bits will dull rather quickly and shatter.

 

[raveney]

Emboldened by the good results with the tunnel ram, I decided to attempt casting a bellhousing. Using the hotwire table and a simple circle cutting jig I made several truncated cones and glued to the mounting plate. Added some thin strips using pins. Filleted using wax and dipped in thinned drywall mud. First time success on the pour again. Didn't bother hollowing the foam pattern. Added some details on the back to mimic a muncie four-speed mounting pad. The roller clutch bearing is accessed here to start the engine.
Much thanks to Kelley over at ZENFORO and on you-tube. He is a master of foam casting full size aluminum intakes and rare parts
ZENFORO Lost Foam Casting Forum

 

[raveney]

hello again,
The ignition system that I wanted to use was (is) no longer available. I settled on a 6V transistor type kit available on Jerry Howell website called a TIM-6. I am terrible when it comes to electronics, but challenged myself to buying the kit and soldered the board so I could learn something. I also attempted the cornstarch and silicone spark plug boots but couldn't get them to release from the mold and gave up after half a dozen attempts. I used several sizes of heat shrink to make the boots. Also made up a set of two, three and four hole wire looms out of Delrin.

This 6V ignition seemed to be REV limited, so after experimenting with several different sized batteries I risked using my lawn tractor 12V and let the magic smoke out after 2 minutes. One or both transistors failed and I replaced them and now limit the voltage to 8V. It revs to about 4500 RPM as tested with a super cheap digital RPM sensor.

Next up was the fuel delivery system. I am using two carbs so a fuel log was made up from brass and nickle plated. I ended up replacing this later as I believed it to be a limiting factor. Using clear hose I was surprised to observe bubbles in the line when the engine was warmed up, so I fabricated two carb spacers and made a phenolic spacer for the fuel log to keep it off the hot aluminum intake. Vapor lock was always my Grandpa's go to troubleshooting advice when anyone's car didn't start. Thanks grandpa

Had my heart set on an aluminum fuel cell and Santa had bought me a Lincoln square wave 200 TIG welder. Silly me made some simple carbon steel welds to make the welding cart and thought "this is easy". Next I made a thin metal sheet bender and a table for my horizontal bandsaw so I could start fabricating the fuel cell. Modeled the prototype using Cardboard Aided Design. The candle on the bench is not for ambience, it is used to soot the thin aluminum sheet before annealing. Black sharpie pen also works but the candle scent IS rather nice...

 

[Scott_M]

CAD - Cardboard Aided Design !!! Nice.

Been there done that

Really nice work, enjoying following along.

Scott

 

[raveney]

TIG welding aluminum is a very difficult thing to do for a novice. I was set on making an aluminum fuel cell rather then a brass tank for this project, so I buckled down and watched dozens of videos on the subject. I ended up listing all of the variables and only changing one thing at a time because of so many opinions on settings, tip grind angle, cleanliness, etc.
The last thing that I changed before getting success was argon flow. I had to increase it to 20 CFH on my setup before I stopped getting oxide.

Aluminum melts at 1400 ish F. Aluminum oxide melts at 2800 ish F. Great for sand paper, bad for welding. Once you get gray-black oxide, or dip the tungsten, STOP. You're done, start over.

The best practice tip was to take two coupons and make outside corner welds, inside corner, edge and flat welds. See coupon labeled 4 below. Once one can do this without turning everything into a puddle of molten aluminum, THEN you can do a box.

I didn't know that at the time and made some pretty "fugly" boxes. See coupon labeled 6 below. I typically have been told how much patience I must have, but honestly I felt like smashing this part violently.

Tank 3 wasn't bad, but a bit large and it failed the air test.
Tank 4 was the keeper. Still not as pretty as professional welders can do, but it worked.
The outside corners were autogenous welds using 0.120" 6061 aluminum, #7 cup, 3/32 ceriated electrode, 120 amps with foot pedal, 70% balance, AC electrode positive, no backing, Cleaned with acetone and dedicated wire brush

In the image above, the engine is running and you can see the tank level is full. I mounted the tank on a vertical slide arrangement with a thumbscrew so I could find the sweet spot without flooding the carburetors. The LED lights are overkill, but green means power is connected, yellow means ignition is powered on, and red is lit each time the spark occurs.

I also chose to leave the rust patina on the metal base for contrast. Many people think its leather. An idea I got from seeing so many rat rod videos. You might also see that I dovetailed the corners of the walnut base. That's a lot harder then it looks.

 

[a41capt]

You are absolutely correct in your appraisal of the difficulties of tig welding aluminum. I did a 12 week U.S. Navy TIG welding school waaay back when and still have the touch, but just once forget to make everything really clean because “it’s just a quick touch up”, and good old aluminum oxide makes you look like a chump.

I keep a dedicated stainless steel wire brush in a clean bag on my welding cart (well hidden from my wife and her barbecue grill scrubbing), and use it religiously before even turning on the gas!

Once again, beautiful engine!

John W

 

[Richard Hed]

TIG welding aluminum is a very difficult thing to do for a novice. I was set on making an aluminum fuel cell rather then a brass tank for this project, so I buckled down and watched dozens of videos on the subject. I ended up listing all of the variables and only changing one thing at a time because of so many opinions on settings, tip grind angle, cleanliness, etc.
The last thing that I changed before getting success was argon flow. I had to increase it to 20 CFH on my setup before I stopped getting oxide.

Aluminum melts at 1400 ish F. Aluminum oxide melts at 2800 ish F. Great for sand paper, bad for welding. Once you get gray-black oxide, or dip the tungsten, STOP. You're done, start over.

The best practice tip was to take two coupons and make outside corner welds, inside corner, edge and flat welds. See coupon labeled 4 below. Once one can do this without turning everything into a puddle of molten aluminum, THEN you can do a box.

I didn't know that at the time and made some pretty "fugly" boxes. See coupon labeled 6 below. I typically have been told how much patience I must have, but honestly I felt like smashing this part violently.

Tank 3 wasn't bad, but a bit large and it failed the air test.
Tank 4 was the keeper. Still not as pretty as professional welders can do, but it worked.
The outside corners were autogenous welds using 0.120" 6061 aluminum, #7 cup, 3/32 ceriated electrode, 120 amps with foot pedal, 70% balance, AC electrode positive, no backing, Cleaned with acetone and dedicated wire brush
View attachment 143306

View attachment 143308
View attachment 143307

In the image above, the engine is running and you can see the tank level is full. I mounted the tank on a vertical slide arrangement with a thumbscrew so I could find the sweet spot without flooding the carburetors. The LED lights are overkill, but green means power is connected, yellow means ignition is powered on, and red is lit each time the spark occurs.

I also chose to leave the rust patina on the metal base for contrast. Many people think its leather. An idea I got from seeing so many rat rod videos. You might also see that I dovetailed the corners of the walnut base. That's a lot harder then it looks.

Every time I want to do some tigging, I have to re-learn it and do a couple hours of practicr. I love doing it but simply don't get much need to use it. Actuqlly, you did quite good for a complete beginner. How long have you been at it? Is it your machine or did you borrow it?