Blew New Cometic .030 head gasket. Compression test reviled 240 ft lbs on front piston at 12 turns wide open and 140 ft lbs on rear piston at the same. I am getting oil leaking at the rear of the cylinder and in the exhaust port. Also oil on the piston. Seems to be oil leaking everywhere. Here are some stats: 10 to one pistons, saved heads .050, Cometic .030 head gasket, Wood W6H cam. Question, does 240 ft lbs seem high and if not is their a gasket better suited for this type compression? Thanks for your help.

 

Might want to check rear exhaust valve guide and gasket for oil problem.

 

Shaving the heads, going with 10 to 1 pistons, and a .30 gasket have put your compression out of site...you are going have to back up and punt.

 

you went way to far with that cam your sitting at around 11.9:1 static and 11:1 corrected.
if you use .060 head gaskets and a w9 cam your still to high. your going to have to start over. either new flat top pistons witch would put you at 9:1 corrected or new heads put you at around 9.2:1 corrected.

 

yea, CR is WAY too high for that cam. get a new cam and bleed some cylinder pressure off.

you shaved the heads 50thou, used domed pistons, AND a .590" lift cam



you sure you didnt whack a valve too?


definitely check guides/seals too. stock evo heads arent even CLOSE to having enough clearance for .590" of lift. learned that from experience.




the sum of all parts != horsepower

 

his piston to valve clearance should be fine but if he didn't machine the valve guides and springs for that lift he probably smashed the seals. that's where the oil is coming from.
my motor has a .650 lift and my valves open at TDC is .220/.201 with domed pistons and .030 head gasket and around .020 off the heads and I have .120 piston to valve clearance on the exhaust and .086 on the intake
his valves open at TDC is .192/.178 that's not much more than stock.

 

Thank all for the replies. The piston is clear no sine of contact but I think you are correct about the valve seals. Do think it will work with a stock gasket .055" over the .030? I really want to save this build if I can. She had crazy power before failure.

 

Correction: Front compression is 230 lbs not 240. Thank you all for the help!

 

if it was mine I would have the heads redone and machine the guides for a .600 lift use .060 head gaskets and put a W9 in it. the W9 only has a .580 lift so if you set it up for .600 you will be safe.
if your compression is 230psi this should bring you down to a manageable level. whoever told you to take .050 off the heads was giving you bad advice.

 

How did you not have pre-ignition at that cr? And did that lead to your failure as well?