Miniature Tunnel Ram on Demon V8

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raveney

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Hello all,
Just finished a customized version of Steve Huck's Demon V8. Started building last May 2021 and it runs pretty well on pump gas and acetone. Learned to nickel plate, TIG weld aluminum, cut dovetails and and cast parts using lost foam method. Its using a Jerry Howell TIM-6 transistor ignition. Made a nice set of gear cutting tools for camshaft drive and distributor along with a mini tubing bender, angle table, hot wire foam cutter and sheet metal brake all learned from the excellent people on this and other hobbyist forums.
I have documented some of the build on camera if any steps would be helpful to others.
The roller rocker arms were the most challenging without use of CNC mostly because of the size
Russ
 
That engine looks & sounds great, congrats!
Sure, look forward to any more pictures, video, build notes.... whatever you care to share!
 
Thank you for the feedback and interest in build notes.

The first parts I attempted were the aluminum roller tip rocker arms. My opinion is that if I could make these, then the build was possible using my equipment and skill set.
It seemed challenging from an order of operations and work holding perspective, so the plan was documented as attached. I redacted the dimensions out of respect to Steve's copyrighted plans.
This is how I did it with an import manual mill, rotary table. The only special tooling was a home made d-bit cutter to create the fulcrum profile. I didn't have a corner radius tool that size.
I think I also fabricated some positive stops for the rotary table and Y axis on my mill for repeatability at this time.
 

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photo #4 shows the fabricated rotary table stops
 

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Very Nice.

I thank you for posting the tooling and setup information: Those things really add to the post.

Do you have another project in mind?

--ShopShoe
 
Those rockers show some serious attention to detail. And 16 of them without CNC? Amazing. Your order of ops smacks of a manufacturing engineer????
What did you use for the actual roller tip? A hard dowel pin and something for the roller? I have a need, ha, ha.
 
Do you have another project in mind?
I had planned to attempt a simple combustion turbine, but the idea was rejected by the household after watching a few videos on youtube. Our neighborhood is a quite one and I draw a lot of attention as is....:rolleyes:

In the meantime, I plan to build a modest electric forge/heat treat oven for tooling shrink fitting and piston rings. Save firing up the propane forge for small bits, and using the BBQ for normalizing.

What did you use for the actual roller tip? A hard dowel pin and something for the roller?
Just used drill rod, but used a #52 (0.0635 inch) to drill the roller so it rotated freely. I did not harden any parts on this engine based on other builder's comments and notes in plan
 
Thank you for the comments and questions,

A few set up notes on the rocker arm pivot pin. They are very small and this is how I thought the best repeatable way to cross drill and ream them. Nothing original on my part, I believe it is something I learned from Joe Pie or Harold Hall, both excellent resources for fiddly bit manufacturing. I did notice that a few rocker studs had loosened when running in the engine and adjusting valve lash, and Loctited them into the heads.
 

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boca bearing has all kinds of small bearings . They might eve have roller making bearing and suitable tip rollers
I had planned to attempt a simple combustion turbine, but the idea was rejected by the household after watching a few videos on youtube. Our neighborhood is a quite one and I draw a lot of attention as is....:rolleyes:

In the meantime, I plan to build a modest electric forge/heat treat oven for tooling shrink fitting and piston rings. Save firing up the propane forge for small bits, and using the BBQ for normalizing.


Just used drill rod, but used a #52 (0.0635 inch) to drill the roller so it rotated freely. I did not harden any parts on this engine based on other builder's comments and notes in plan
 
Thank you Bentwing, I have ordered bearings from Boca. They are an exceptional company as they wrote a nd included a handwritten thank you note, and included sticker sheets, mouse pad and a laminated bearing size sheet.

Following the tedium of the rocker arms, I was relieved to work on the one-off parts like cylinder block and oil pan. Both needed to be fitted before boring the cam and crank journals. I purchased a long reach (3-1/2) carbide 0.250 3 flute bit that was very rigid and gave excellent finish. Spe makes it and sells for a reasonable price I thought.
https://www.amazon.com/gp/product/B07VZM3PLL/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
After heating the machined block up in a toaster oven, I pressed the cylinder sleeves in and air tested in the sink. In hindsight, I should have re-lapped the bores at this point, but did not have a blind hole lap. Many months later I found out this step was needed and had to tear down the engine to do it on 6 out of 8 bores. Guessing that the interference fit caused an eggshape?
 

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This same thing happened to a race engine they pounded new sleeves into a hot block which resulted in stuck sleeves now these had a 4” bore so they were really stuck. Broke two special steel sleeve pullers . The final solution was to get a large canister of air conditioning Freon and spray the sleeves then quickly use. New steel slide hammer puller . Lesson learned the hard way . Sleeves are no dry fitted in a cold block . Blocks are solid aluminum. Sleeve get polished fo a slip fit so they simply push it easily after a run if necessary . The block is pretty hot then but at least at home it’s cooled so the sleeves come out easily . Honing in a iron block is tough as you have to have a stop on the hone so it doesn’t grab the bottom of the block .

Sleeves get out of round but carefull honing you can straighten them hand honing I an art. Most race guy just send them to the mfg. unless there is a honing shop close by . Just squeezing them can make them out of round.



Thank you Bentwing, I have ordered bearings from Boca. They are an exceptional company as they wrote a nd included a handwritten thank you note, and included sticker sheets, mouse pad and a laminated bearing size sheet.

Following the tedium of the rocker arms, I was relieved to work on the one-off parts like cylinder block and oil pan. Both needed to be fitted before boring the cam and crank journals. I purchased a long reach (3-1/2) carbide 0.250 3 flute bit that was very rigid and gave excellent finish. Spe makes it and sells for a reasonable price I thought.
https://www.amazon.com/gp/product/B07VZM3PLL/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
After heating the machined block up in a toaster oven, I pressed the cylinder sleeves in and air tested in the sink. In hindsight, I should have re-lapped the bores at this point, but did not have a blind hole lap. Many months later I found out this step was needed and had to tear down the engine to do it on 6 out of 8 bores. Guessing that the interference fit caused an eggshape?
 
experience of using fuel that is a mix of pump gas and acetone
Sorry,
I should have typed it runs well on either pump gasoline or acetone. I have never attempted to mix the two. Acetone is what I use for flame lickers, heat engines and a hit and miss engine that I have built. Runs "cleaner" when comparing the exhaust smell and doesn't foul plugs and tiny fuel intake parts like gasoline does.

The spark plugs are very very small on this engine.

You need special lined hoses for acetone though which I buy at McMaster. Com. I ruined the yellow weed-eater hoses I had on hand after several runs on this engine, so swapped back to pump gas.

The fuel/exhaust smell enhances the sound and experience of running this engine. 😁I brought it into work to show the maintenance guys, and one guy put on ear muffs it's so loud.
 

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@raveney I've been collecting tube bending ideas & pictures for a build this winter. If you have any pictures to share I'm interested to see them.

You sure did a nice job on that engine!
 
I've been collecting tube bending ideas & pictures for a build this winter. If you have any pictures to share I'm interested to see them.
Thank you Petertha,

I am a bit intrigued by tubing benders also, and selected the Horace Clarke one to replicate and use for the headers. Some photos attached below of the tool and headers being fabricated from 5/16 OD brass 0.032 wall rigid tube. I believe the plan is posted on this forum. I deviated slightly by welding the fork rather than pinning. Also needed 0.100 more clearance at the back where the removable handle attaches to clear the larger radius steel dies.

I annealed the brass tube before bending, and used a jig so they would be symmetrical. Brazed them and then copper/nickel/SS plated. Very pleased with the end results. The copper/nickel/SS was accidental as I was using copper wire to suspend the nickel in the bath until I realized what was happening. Then I switched to a short piece of SS braided wire to suspend the piece of nickel; saw it was also dissolving, but liked the finish.

The blackened tubing bender shows the aluminum dies which were easy to make, but resulted in some tube ovality which needed fettling to look good. I heard there are numerous tricks to preventing this. the steel dies were made later for some 1/4 OD 0.071 wall SS tube and they came out perfect.

When I have more time and room in my garage, I would like to fabricate the Hossfeld bender in 1/2 scale as it appears way more versatile.
 

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