low-compression head gaskets--do they work?

Hi all,

1990 Evinrude 90 hp

Still having a difficult time getting this motor to run right. It ran ok all summer, other than starting hard when warm and not idling. I took it to another shop; the tech took the powerhead apart to see how bad the cyl. that locked up was. (see post from last year--horror story.)
To my surprise, it didn't look all that bad, but he told me the other 3 cylinders are badly worn and were never bored out on the first rebuild, and should be bored out and have new pistons. He's also recommending low-compression head gaskets, since the first guy I paid to rebuid the powerhead ended up "decking" the cylinders, which he said increases compression. Does anyone have experience using the low-compression head gaskets? Do they work? Thanks.

Re: low-compression head gaskets--do they work?

Decking the block is to be avoided, if possible, like a disease. Fortunately the thick head gaskets are a viable alternative. Sounds like you found a good tech.

Re: low-compression head gaskets--do they work?

Ask your new mechanic what he expects the cranking compression to be when he is finished with your motor.

Depending on exact year/model cylinder heads expect compression to be near 120.

J/E came out with the 'low compression' gasket when the fuel quality started going away to avoid possible running issues.

Time has shown that lowering compression ratios was not really necessary. The problem arises when CRANKING compression exceeds 150 psi, keeping compression under 145 and you should have no problem running stock timing and get great performance and reliability from your motor.