The Ford Barn - View Single Post

Bored&Stroked · 02-21-2016, 01:02 PM

If you're milling it to have .050 clearance, than the only reason it would need to be reworked is if the head dome profile/radius differs from the piston crown radius. I've noticed that some of the cast pistons tend to have a different shape than ones like Ross (forged). Also, it depends on the true crankshaft stroke deck height, etc..

As 'flatheadmurre' noted, the only true way to know is to mock-up the block (with the actual crank, rods and pistons you're using - which means the block has been bored) - then see where you are at with the heads. You'll probably find that the clay will have an inconsistent thickness - due to the dome/piston shapes not being the same. I'd say you can get as close as about .040 on a street engine and be okay (it is what I aim for).

I recently created a 3D CAD model so I could have my new Navarro heads CNC milled to make the chambers exactly match my pistons (Ross, custom ones). I found that the Navarro domes really didn't match the Ross domes -- more 'peaked/pointed' than a true consistent radius.

If you have access to a CNC mill and somebody who can redo the chambers, might not be a bad idea. My guy just used a 1/4" ball mill and I smoothed the final machine work out with a die grinder.

02-21-2016, 01:02 PM	#3
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,070	Re: Combustion chamber reshaping If you're milling it to have .050 clearance, than the only reason it would need to be reworked is if the head dome profile/radius differs from the piston crown radius. I've noticed that some of the cast pistons tend to have a different shape than ones like Ross (forged). Also, it depends on the true crankshaft stroke deck height, etc.. As 'flatheadmurre' noted, the only true way to know is to mock-up the block (with the actual crank, rods and pistons you're using - which means the block has been bored) - then see where you are at with the heads. You'll probably find that the clay will have an inconsistent thickness - due to the dome/piston shapes not being the same. I'd say you can get as close as about .040 on a street engine and be okay (it is what I aim for). I recently created a 3D CAD model so I could have my new Navarro heads CNC milled to make the chambers exactly match my pistons (Ross, custom ones). I found that the Navarro domes really didn't match the Ross domes -- more 'peaked/pointed' than a true consistent radius. If you have access to a CNC mill and somebody who can redo the chambers, might not be a bad idea. My guy just used a 1/4" ball mill and I smoothed the final machine work out with a die grinder.