Piston mods or thicker head gasket?

howdydog

New Member
Just sitting here pondering. I have lots of oem cylinders, pistons and heads sitting around along with a few aftermarket heads. I know the domed pistons hit the aftermarket head could I machine down the domed piston to clear the head or make a thicker copper head gasket to get the clearance? Again just thinking out loud.
 

Robert thran

Well-Known Member
There was a guy on eBay selling copper head gaskets. I contacted him awhile ago and he said he could make me one in any thickness I wanted..I’ll see if I can kind him if he’s still making them or still selling.
 

howdydog

New Member
I was a honda mechanic from 1972 -1986 we would build race 50's using a 70 cyl and a 50 head with 4 base gaskets . ad lots of problems sealing the oil passages.
 

Old Guy Too Many Bikes

Well-Known Member
When I used to build stroker motors, to set the deck height, I'd use barrel spacers machined out of steel to figure out the correct compression ratio. I even put a set on my old shovelhead to keep it from pinging on our crappy gas. But as cheap as new pistons are, it may not pay.
 

fatcaaat

Well-Known Member
you can maybe trim a max of .25mm off the deck of a piston safely, but any more, and you'll have issues. i just recently went through this and milled a piston down because the CR was pinging the engine. I cut it down and it ran great...for about 8 total miles...and lost compression. Took it home and found a hole in the piston.
 

Old Guy Too Many Bikes

Well-Known Member
You could get a piece of sheet steel, use a base gasket as a template and make a spacer. If you're clever enough, you can calculate your desired compression ratio and pick a correct thickness to suit. Volume of a cylinder is pi x R(squared) x H. R=bore/2, H=stroke. If you can figure out combustion chamber volume (using liquid), and volume of your piston dome, it's quite simple actually. Cylinder volume + combustion chamber volume + cylinder deck height volume / combustion chamber volume + deck height volume = compression ratio.
 

howdydog

New Member
These are great ordered all three to play with. I just converted my old harbor freight blaster to vapor works great, and a few of my herd.
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--
 

kirrbby

Well-Known Member
VERY nice!
Man the vapor blast is impressive too. Looks like...aluminum paint...from the old days. Back when paint was...VERY stinky. lol
 

howdydog

New Member
Good eyes! 1970, 650 Tiger owned since 1974 all stock except the rear fender and sissy bar just put 35 miles on her yesterday! Have 3 more including a Rickman 500 with a Joe Hunt Mag. Not good pics oof the shop but only one's I have right now.
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howdydog

New Member
My high school car 1970 Cuda 440 six pack now a 512 stroker. I built a rotisserie an replaced the rear quarters and trunk pan in 2018
 

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Robert thran

Well-Known Member
Sweet mopar…I watch graveyard cars every week…to me the best car restoration show on t.v.! I wish I still had my 340 4speed 3.91 geared demon.. that’s one car I could kick myself in the ass for selling!!!
 

howdydog

New Member
I hear you. I have been lucky to have had acreage and buildings for storage all my life, along with cattle and farming to support all our food needs. I do have many regrets as to thing I have sold that I should have kept, or ran through the demo derby 70 chevelle , 72 roadrunner, 70 charger rt, 68 fury, countless mustangs but back then they were $150 cars. the darn Fords lower ends kept blowing up , the mopars are much better. Bikes are to many to count had over 75 at 1 time. Down to about 20 now none newer than 1979. Should have kept the 2 stroke street bikes but still have a nice RD350 my wife rides
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. I just wish my boys shared my love for these old jewels. Nothing like the sound of a vintage bike or the torque of a big block.
 

fatcaaat

Well-Known Member
What media are you using in the vapor blast? My setup produces a modern factory surface, maybe even a little nicer, but yours is trending toward polished. What you have in there?
 
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