Flathead V-8

[gbritnell]

As I had mentioned in the earlier posting it's down to finishing up the small things now. First on the agenda was making proper hot rod acorn headed bolts. The original plan was to use stainless socket head screws but the more I looked at it the more I just wasn't happy with them. I purchased a couple of boxes of 1.00 long screws and they fit the bill perfectly. There is about .200 of unthreaded shank just below the socket head. The diameter is .200 which makes it a perfect fit for a #31 drill when making the acorn heads. I made a split bushing with a 5-40 thread through it to hold the screws for cutting off the heads after which I used the jaws on the chuck as a guide to file small flats at 120 degrees apart on the shank. These would be for the silver solder to wick down into and hold the heads to the shank. I purchased a length of 3/16 stainless hex rod and made up 40 acorn heads. I held off putting the radius on the heads until they were soldered onto the shanks. With all the soldering complete and the pieces cleaned I mounted each one in the split bushing and with a hand ground radius tool formed the tops of the heads. When the machining was complete I buffed each head being careful not to round the edges of the hex. To go with each of the 40 bolts I made up .03 thick washers.
I had thought that I might have to set the heads up again to enlarge the spot faced area around each bolt hole for socket clearance but as it turned out I turned the hex socket down to the point where it had about .02 of material over the high points and it fit fine into the existing pocket.
The end of each bolt was coated with a non hardening sealer and then screwed in place. The reason for the sealer is because some of the bolt holes go directly into the water jacket.

[Don1966]

Looks dam good to me George and that could be because I like acorn nuts. But on your engine it looks superb........... 


Don

[gbritnell]

Up next was the water connections from the engine to the radiator. On some of the hot rodded flat heads they use a decorative tube between the engine and rad so I bought a piece of 3/8 stainless tubing for the job. I had to use my larger tubing bender because the small one only goes to 5/16 inch. I bent up a piece of heavy copper wire to get the shape I wanted and then cut and bent the stainless tubing. The tubes were then buffed and polished.
To make the hose clamps I slipped the tubing over the nipples and measured the O.D. I then turned up some stainless stock making the I.D. about .01 smaller than the measured size. The thickness is .015.
The bushing piece was drilled and tapped 2-56 then clearance drilled .093 dia. half way through. The extra diameter for the clearance allows the clamp to flex without binding the screw.
Each of the bushings were silver soldered to the rings then boiled in water to remove the flux. They were then clamped into the mill vise leaving just enough of the rings sticking out so that the slitting saw could go through the bushing and ring wall. I used a .040 slitting saw.
The radiator cap was also finished with the valve inside. I used bronze spring wire to make the spring so it could be soldered to the valve and bushing to hold it in place.

[gbritnell]

It's getting close. Dave, probably in a couple of weeks will be the first starting test.
Just a few more pictures of the engine at this point.
gbritnell

[Roger B]

Your detailing is magnificent    I am eagerly awaiting the first run 

[Don1966]

That's just to sweet. Love the hose clamps ................


Don

[ozzie46]

That is absolutely gorgeous George.

Ron 

[Dave Otto]

Continues to be amazing George!

Having seen the acorn hardware on flatheads many times over the years I never gave a thought to whether they were studs and nuts or bolts. I always assumed that they were nuts; now it makes since. Nuts and stud lengths would be a royal pain to deal with.

Thanks,
Dave

[Kim]

Just amazing George! Unbelievable...
Kim

[Mosey]

Beautiful George!
When will you show us the little scale men who do all of the work for you?
 
Mosey

[fumopuc]

Speechless, again. A masterpiece. The hose clamps are beautifull.

[RickCHodgin]

Amazing, George.  Absolutely stunning.  I've sent this out to some of my friends.

[gbritnell]

Gentlemen,
 As with most of the more complex builds I have completed over the years the building part is just one segment of the whole story.

 When I ran the engine in the lathe to loosen everything up I didn't have the heads on. As it was turning over I placed the heel of my hand against each cylinder and the compression was good. After installing the heads the compression didn't seem that good but at that point it wasn't a great concern.
 
 Two weeks ago I had everything ready for the first try at starting the engine. I set the timing ( a story in itself) fueled up the tank and gave it a spin. The only thing I got out of the exhaust pipes was some tiny puffs of smoke but nothing like it was trying to run. I changed the timing settings a little both ways but still no luck. I unhooked everything and took it back down into my shop. I turned the engine over by hand to check out the compression issue. Once again it didn't seem too good.

Having only built overhead valve type engines the combustion chambers were just an extension of the cylinder bore with enough room for the valves to clear the top of the piston at TDC. I can't say I every really calculated what the compression ratios were, they just seemed to be in the ball park.

With this flathead engine I designed the combustion chamber what seemed like proportional to the bore and stroke. What I didn't account for was all the extra combustion chamber space that goes out over the valve area. At this point I pulled out the calculator and did some long hand math. It was hard to get an exact number given the extremely irregular shape of the whole combustion chamber but I came up with about 5.2:1 compression ratio. Not so good!

 It was at this point that you have one of those V-8 moments (slap to the head). I have Solidworks on my computer so I drew up the combustion chamber and let the program do the volume calculating. I only play with Solidworks for my own enjoyment and have never used that feature before. When all the final numbers were in the actual compression ratio is 4.8:1. Really bad.

 Now having been a hot rodder in my younger days there are two ways that a person can go to gain compression, one is to shave the head, the other is to put pop-ups on the pistons. In my case milling the head wouldn't get me where I needed to be and making totally new lower head pieces didn't look that appealing. That left pulling the pistons and making new ones. I went back to Solidworks and kept adding material to the top of the pistons until I came up with a 7.75:1 C.R.

 When I made the original pistons I had cut a third groove for an oil ring but the rings I designed all broke when I tried to install them so I just went with the two compression rings. I did the same with the new pistons figuring that once I got the engine running I could come up with a new oil ring design that would work.

 I made the new pistons and put everything back together. I chucked the engine up in the lathe and spun it over to loosen up the new rings. While turning it over I could feel the engine bumping against the compression with the new pistons. So far so good! As I was turning it over a new problem arose. The engine was spitting quite a bit of oil from the exhaust pipes, I mean quite a bit. I thought if I let it turn over enough the rings would seat and this issue would go away. Not to happen!

 I pulled the heads and drained the oil from the tops of the pistons, wiped everything out, remounted the heads and took the engine out for the second attempt at starting. With everything hooked up I cranked it over and it fired up for just a brief time before it oil fouled the plugs and blew a bunch of oil from the pipes.

 This takes us up to date. I'm guessing that with no ring in the oil groove in the piston what should be oil drain-back holes are putting too much oil on the cylinder walls this causing the oil bypass of the compression rings. Right now I'm experimenting with some new oil ring designs. If that fails I'll just make a third ring to fill in the oil ring groove.

 Sometimes the fine tuning can take quite a bit of time and this engine is turning out to be now exception.
I'll keep you posted. With New Years and all it's activities it'll be a few days before I have a chance to get back to experimenting.

gbritnell

[Don1966]

A bummer to hear George, but I have no doubt that you will have running when you return. Good luck my friend and I will be waiting to see this engine running at it's finest.

Don

[Doc]

I'm sure you'll get it sorted out. You do some fantastic work by the way!