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Guest Anonymous

compression

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Guest Anonymous

I ran a compression test with a friend today and my compressions were 1. 137, 2. 125, 3. 146, 4. 130, i was wondering if anyone knows what good compression numbers would be and if there is anything i can do in order to make it better... thanks

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Guest Anonymous

With low compression pistons, I believe an average of 150 is good. But what is most important is that all cylinders are within 10%.

How to make it better? First, you want to know if it is the head or the bottom that is at fault. Pour a small spoonfull of oil each cylinder and do a compression test. If suddenly the numbers get much better, it is beacuse the rings are at fault. if numbers stay about the same, then it is the head.

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Guest Anonymous

(nt)

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Guest Anonymous

I have used Marvel mystery oil to free up rings and crud around valves. Can't hurt and may help.

My mom's husband was a farmer and would "resurect" old diesel engines that laccked enough compression to start by dumping "bonamy" powdered hand cleaner into the intake and crank the engine over until it started and run it for a few minutes. Drain the oil a few times to remove most of the powder. The grit, I think it was pummice, would grind into the rings and cylinder walls and reseat everything and get enough compression to finish the harvest then rebuld it before the spring planting. Probably only in an emergency in your case. Have fun

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Guest Anonymous

it remembers me the old trick of pouring wood particle/dust into a noisy differential...i never try it...

Pat Allen

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Guest Anonymous

(nt)

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Guest Anonymous

tn_enginebay03_JPG.jpg

URL: http://www.zeebuck.com/bimmers/tech/Megasquirt/megasquirt.html

The valve adjustment is critical. Getting it within spec is important, but even more importnat is to get them all even cyl to cyl. Variations in valve clearance result in variations in overlap and the effective compression ratio.

I shoot for .007" exhaust and intake (stone cold motor), with a .008" feeler gauge being a definite no-go. .007 is right in the middle of the acceptable range.

regards,

Zenon

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