Chevy V8 Scale Engine Plane

[SailplaneDriver]

I'm going through all the drawings and trying to model it in Fusion 360. I've gotten up to the crank shaft. It is a good learning exercise for Fusion and helps me understand the components. Most every time I have a question I look back at the drawings and find my answer. Steve, you did a great job putting these together.

What is the best way to ask questions about this build, here or start a new thread?

 

[doc1955]

If I can help you out here is a good spot yes Steve did a good job on the drawings. I finally put headers (or collectors) on mine and am not going to use the zoomie pipes.

 

[SailplaneDriver]

Okay, here are a few questions I have come up with for now. I suspect I will have more once I review the other parts in detail.

• Which method did you use for the crankshaft, one piece or built up?
• What parts have critical tolerances? I don't see any tolerances on anything except for a few notes.
• Should the lifter be brass/bronze as well as the guide? I'm used to steel lifters at least in full size engines.
• How do you enlarge the water jacket in the cylinders on a manual mill? It would be a piece of cake with a CNC. The only practical way I see is using a rotary table with a separate setup for each cylinder.

By the way, the heads and intake manifold look like nightmares.

 

[doc1955]

My cranks both were one piece
My lifters are not per drawing I went a different route they were made of aluminum 7075.
The water jackets I used a wood ruff cutter also known as keyway cutters. I did use cnc but it's not necessaryto get it all the way around if you just go it an x and a y move.
Tol the clank journals will need to be within I'd say +- .001 the valve guides you can be a little loose on the tol as long as the valve going into it is a nice snug slip fit.
The part I had the most trouble with was the intake the heads not so much if you make holding fixtures to hold them while machining.

 

[stevehuckss396]

I did a one piece crankshaft from 1144 steel. It's a bit harder to do but well worth the effort.

Pistons and crankshaft bearings need to have a good fit. 6061 pistons I made 1-1.5 thou smaller than the bore. Bearings are .5-1 thou larger than the crank diameter. Slip fits should be just that so about .001. Press fits for the cam gear and bearing should be .0005-.001 smaller.



The lifter bushing should be brass or bronze. The lifter should be 12L14 steel

Use a 5/8 key cutter to machine the jackets. Center over the bore and lower the tool to height. From center move north .093, south .093, Back to center, east .093, west .093, back to zero. Then move north .063, east .063, south .063, west.063, north .063, back to center. So basically you go up, down, left , right in a plus sign pattern and then up, right, down, left, up in a square pattern. Then back to center and advance the tool into the bore some more and repeat until you get the entire bore cleaned out.

 

[stevehuckss396]

I'm going through all the drawings and trying to model it in Fusion 360. I've gotten up to the crank shaft. It is a good learning exercise for Fusion and helps me understand the components. Most every time I have a question I look back at the drawings and find my answer. Steve, you did a great job putting these together.

What is the best way to ask questions about this build, here or start a new thread?

If it is a general question about engine building you can start a thread. If it is a specific question about the Demon V8 you can ask in the "small V8" thread. That way all the Demon questions are in the same place.

 

[CamaroNut]

Steve, do you have a video of a little Demon with the super charger running?

 

[stevehuckss396]

Steve, do you have a video of a little Demon with the super charger running?

No I do not. I started working on it again and then I decided to get into the spark plug business. It is at the top of the list.

 

[SailplaneDriver]

The crankshaft doesn't show any counterweights. Is that an issue with balance?

 

[stevehuckss396]

The crankshaft doesn't show any counterweights. Is that an issue with balance?

No. but the next one will be more conventional. See what happens

 

[doc1955]

I did the crank both ways and really didn't notice much difference at all.

 

[SailplaneDriver]

I'm now looking at the camshaft. I tried in vain to locate Steve's thread on making the cam. Can you point me in the correct direction?

 

[stevehuckss396]

Here is the write up.

 

[SailplaneDriver]

Thanks. Now I understand how the fixture and the chart works. Please confirm my interpretation that the cam lobes on the blank (page 17) are EX1, EX2, IN1 ... EX8.

 

[stevehuckss396]

Front of the cam is on the right on page 17. EX8. . . . . EX1

When turning the front will go toward the spindle (left) so the lobes will match the chart while turning.

 

[SailplaneDriver]

How critical is the squareness and parallelism of the initial engine block stock? I'm fighting jaw lift with my import vise.

 

[stevehuckss396]

How critical is the squareness and parallelism of the initial engine block stock? I'm fighting jaw lift with my import vise.

Hard to say really. Everything can tollerate a little but how much I cant say.

 

[doc1955]

Use a piece of small round stock on movable side when clamping that way your stock will set up against the solid jaw and it should take care of the movable jaw lift.

 

[SailplaneDriver]

I had to resort to using a piece of paper on the fixed jaw to compensate for the lift. The faces are now within .oo15 for square and parallelism. Closer than that and I will have to clamp directly to the table and forgo the vise.

 

[doc1955]

If your back jaw is perfectly trammed in to 90 degrees to your machine head using the method I suggested you can get within .0005 fairly easy. You take the jaw lift totally out of play that way.