Question about compression & squish

[Sraydoo]

97 Challenger 1800 - twin 787s - new to me, and lots of restoration ongoing.
I show 210 psi in both cyl. (too high)
Squish is 0.090 (too large)
if I put an additional 0.030-0.040 base gasket ... won't compression increase?
am I missing something?

 

[mikidymac]

Are you sure you don't have oil in the crankcase from leaking seals?

If you already have high compression and too much squish ten somebody machined the head incorrectly and it needs to be fixed or replaced.

 

[Sraydoo]

Thanks mikidymac,
so I am guessing the first thing to do is to pull the cylinders and get the squish in spec.... Correct?
if I had 090 and I see a 5 dot base gasket, should I get a 3 or 4 dot gasket?

probably replace the head while its apart.

 

[mikidymac]

If it was me I would pull the head and see if it looks like it was machined. There is no way a 5 hole gasket should be 210 psi. Are you sure the gauge is correct?

 

[Sraydoo]

I believe the gauge is correct my other engine is showing 145 / 148 psi.
the compression issue may have been oil getting in . not much in cylinder but there was in the crankcase.
I did tear the top end apart, head looks good. I have another head from a spare.
measured the squish with each head (AND NO base gasket) = 067-071" with no gasket ????
can I go with no gasket???
or ???

 

[mikidymac]

Something isn't correct. You can't have that much squish without a gasket.

 

[Sraydoo]

My piston has 1.00 does that change the squish gap target?

 

[mikidymac]

No.