Increasing compression - Milling?

[Chuckcruzin1986]

Can I mill the head .050" without a problem (I will check valve clearance with clay and mill proper clearance)? I am using Super eta pistons in a 2.7 block which are 8.5 - 1 to start. I want to end up with 10-1

I will also mill the outter edge of the piston so to leave .035" to clear the head when the piston is at top dead center.

ideas??

Chuck

[xwill112x]

if you mil the head, your going to need a adjustable cam sprocket. just fyi.

[jlevie]

You've posted this question twice, with no definitive answers. That is probably because no one has tried this before. Try it and tell us how it works out.

[Chuckcruzin1986]

OK, here goes. First step done

You've posted this question twice, with no definitive answers. That is probably because no one has tried this before. Try it and tell us how it works out.

.050" milled. Next step is to cut the combustion chamber edge so the pistons will not contact the head.
Chuck

[Chuckcruzin1986]

Combustion chamber milled for piston clearance

I am just a beginner. Hope it works

[Alpinweiße30]

Looks good, but I cannot comment to the orginal question

[briansjacobs]

sorry I am a little late, but milling the head for compression is less than ideal as it removes contact area for the head gasket. I suggest upgrading the head gasket/studs and make sure your timing is spot on through all RPMS.

My race car had a milled head for compression and the timing was off, we went through 3 head gaskets before we found the problem with timing in the chip.

[Chuckcruzin1986]

I am just doing it.

Looks good, but I cannot comment to the orginal question

I am keeping my fingers crossed. One problem is that it is hard to measure the amount that the piston protruds into the combustion chamber........therefore, measuring the exact compression ratio is tough so i am just making an educated guess.

Chuck

[Chuckcruzin1986]

Timing?

sorry I am a little late, but milling the head for compression is less than ideal as it removes contact area for the head gasket. I suggest upgrading the head gasket/studs and make sure your timing is spot on through all RPMS.

My race car had a milled head for compression and the timing was off, we went through 3 head gaskets before we found the problem with timing in the chip.

Going from 8.5 - 1 to approx 10 - 1 will require engine management to be safe and squeeze max power. I will also be timing the camshaft. I have also ground the rockers. See image and video. We will see :-D

Video of rockers being ground: http://www.youtube.com/watch?v=WAgalIMddns

[bear]

so hows this going? won't milling you comb chambers negate the compression gain?

[e30ne21]

Do a mock up with a used crushed head gasket to check piston to valve clearance. 0.020 is about the most you hear about on budget strokers and even that's close with the stock cam.

[Chuckcruzin1986]

Milling the combustion chamber?

so hows this going? won't milling you comb chambers negate the compression gain?

When you mill the head, there is an area that will be hit by the piston. The area is fairly small (I did not cut the main bowl).

the truth is, I did kind of get lost on this: .050 off the head, .003 off the block, cleared the pistons where the valves would have hit, milled the outside edge of the piston and mill the area of the head where the piston would have hit. Soooooooo, I really don't know my exact compression ratio , BUT, I am sure I have increased it quit a bit.

Chuck

[Chuckcruzin1986]

Major machining

Do a mock up with a used crushed head gasket to check piston to valve clearance. 0.020 is about the most you hear about on budget strokers and even that's close with the stock cam.

I did some major machining and did check everything with clay. I checked a used gasket compared to a new one. The used one was only .001" thinner!!

Chuck

[nando]

Do a mock up with a used crushed head gasket to check piston to valve clearance. 0.020 is about the most you hear about on budget strokers and even that's close with the stock cam.

.020" piston/valve clearance? that's way too little, you need 1.5mm minimum.

[Chuckcruzin1986]

Ground the top of the block today

Ground about .003" off the top of the block :)

Chuck