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Old 01-08-2012, 08:30 PM
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Default found the major problem

I never could get the motor run smoothly since her big sleep in 1978. I had pulled one head a few months ago to check condition, assumed both banks where the same.

Had the problem that one side of the exhaust ran much hotter than the other. This puzzled me because the cylinder pressure was good on both sides of the motor.

I finally decided to pull both heads replace the rings and check both heads.

Well one cylinder has a little hunk about the size of a pencil eraser out of the bottom of one cylinder.
Its way past cylinder travel so I don't see that as a problem but at the other end,............

the cylinder is leaking between the head and the top of the cylinder.


Here is my question did it leak because a head bolt was loose. Or do I need replace the cylinder or do I need to shim the cylinder. There is only 500 miles on these cylinders and pistons.

The funny thing is the hunk that's gone is almost parallel with the black mark where it was leaking and almost perfect between centered between two head bolts at the head.

Do I need to post pics or is what I said clear.
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Old 01-08-2012, 10:28 PM
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If you could post a photo, Dale, it may make it a little clearer. In short, it sounds like the cylinder skirt where it bottoms on the deck of the block has been damaged, yes? I can't see any major issue with that either other than a possible oil leak location, but then again you might be surprised how far down the pistons actually travel into the block. On stroker motors the internal webs of the block sometimes have to be clearanced to miss the skirt on the piston... it's possible that the bottom most ring on the crown is just connecting with that piece missing on the cylinder. That would lead to scored walls, leaks, you name it. It also sounds like whomever built (rebuilt) the engine was careless and knocked that cylinder on something to chip the bottom. If it were me I'd replace the cylinder and the piston as a unit just to be safe.
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Old 01-08-2012, 11:57 PM
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ok here is some pics

on the cylinder end of the cylinder the oil trail is not as clear so I am including a pic of the back of the head

You can see the cross hatching in the cylinder. so the piston does not go that far so I think its ok

looks to me I cylinder leakage.

I got 95 lbs of pressure out this cylinder and it held it for for about 10 minutes until i released it.

I wonder if it opened up when it was hot and lost pressure.
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Old 01-09-2012, 11:22 AM
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Is that at the head side or the block side of the cylinder? Head side would make far more sense for a leak..
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Old 01-09-2012, 10:10 PM
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Quote:
Originally Posted by letterman7 View Post
Is that at the head side or the block side of the cylinder? Head side would make far more sense for a leak..
head to cylinder

The big black spray pattern is the leak on the head.

I also figured out today that the stud where the leak was was loose.
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Old 01-09-2012, 10:14 PM
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Ok... then the cylinder is toast. There's no way to keep compression there since any shims are supposed to be under the cylinder at the block, not the head. Once it gets hot all bets are off. Replace the cylinder and piston as a unit. Depending on the type of piston, the top ring is almost certainly scored.
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Old 01-10-2012, 10:50 AM
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Quote:
Originally Posted by letterman7 View Post
Ok... then the cylinder is toast. There's no way to keep compression there since any shims are supposed to be under the cylinder at the block, not the head. Once it gets hot all bets are off. Replace the cylinder and piston as a unit. Depending on the type of piston, the top ring is almost certainly scored.
it's not scored i'll send a pic. Also the cylinder has no scratches in it either. That head bolt was semi loose as well. It did not feel like it had any torque on it when I removed the head. I pulled the cylinder I found that the stud rod was loose as well ( removed them to clean )

Can't believe how clean the pistons are
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found the major problem-1234-477.jpg   found the major problem-1234-479.jpg  
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Old 01-10-2012, 12:50 PM
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Wow.. yep, still looking like new . I only see one small nick in one of the rings, but it wouldn't be enough for an issue on a stocker. The blowby is certainly from the nick on the cylinder end. Either way you'll need to repair or replace it - I'd be willing to bet most of that blowby was as the engine was warming up.
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Old 01-10-2012, 09:17 PM
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TO TELL THE TRUTH I'm tired of jacking around with it. I took the heads today to the machine shop. I'm going to new jugs and pistons. And put it back together. Then I am down to tuning the carbs.

Oh by the way mic'd the piston's they were not 94mm's like the previous owner said just 87mm pistons
Oh well 87s is what I am going to put back. have you ever heard of

AA performance cylinder and piston kits.
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Last edited by delbertinie; 01-11-2012 at 08:51 PM.
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