Slant Six Forum :: compression wimpy...whats going on?

: I did a compression test yesterday and it was
: 120-122 per cylinder. It was at 110 before
: with a 115k on the motor! Something is
: messed up. I'm wondering if it is my head
: and block that are bad. If the cam was off
: how much would that affect the compression.
: I re-torqued the head bolts yesterday. There
: is also an annoying white foam that gets in
: the radiator after driving for about 10-15
: minutes. I'm wondering if the head gasket is
: slightly messed up.The dipstick appears
: okay. I'm thinking of starting over and
: buying a roach valiant convertible.

Author:	Scott Woebcke [ Thu Oct 11, 2001 10:54 am ]
Post subject:	compression wimpy...whats going on?
I did a compression test yesterday and it was 120-122 per cylinder. It was at 110 before with a 115k on the motor! Something is messed up. I'm wondering if it is my head and block that are bad. If the cam was off how much would that affect the compression. I re-torqued the head bolts yesterday. There is also an annoying white foam that gets in the radiator after driving for about 10-15 minutes. I'm wondering if the head gasket is slightly messed up.The dipstick appears okay. I'm thinking of starting over and buying a roach valiant convertible.

Author:	Doctor Dodge (Doug Dutra) [ Fri Oct 12, 2001 7:05 pm ]
Post subject:	Re: compression wimpy...whats going on?
Quote: : I did a compression test yesterday and it was : 120-122 per cylinder. It was at 110 before : with a 115k on the motor! Something is : messed up. I'm wondering if it is my head : and block that are bad. If the cam was off : how much would that affect the compression. : I re-torqued the head bolts yesterday. There : is also an annoying white foam that gets in : the radiator after driving for about 10-15 : minutes. I'm wondering if the head gasket is : slightly messed up.The dipstick appears : okay. I'm thinking of starting over and : buying a roach valiant convertible. The "white foam" is not good... 120-122 is a bit low, try loosing the valve lash some to see if cranking compression goes up. Even with low but even compression readings, (white foam aside) I would suggest cranking-up the distributor advance to get more performance. Low compression engines run pretty good if you give them a lot of spark lead) Cam "profile and "installed centerline" has an impact on your reading. Advancing the cam will increase the cranking compression but at the expense of top RPM performance. The mechanical compression ratio has the most effect on cylinder pressure readings, mill the head and / or the block. Take measurments and do the compression calculation. (untill you measure, you just don't know) DD

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