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My compression test results

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BurrowZ

10+ Year Contributor
836
5
Nov 28, 2010
Duluth, Minnesota
Alright, I've been having trouble with hot starts and cold starts. Both take a few tries and on hot starts I have to give it gas to keep it alive. Mods are up to date, I haven't thrown a solid tune on DSMLink v2 yet but just good enough to get it running safely.

Anyway.
2G stock 7 bolt block - 98k
1G head unknown mileage
HKS 264/272 cams
BC valve springs
NO boost leaks
-8in/hg @ 800rpm idle

Harbor freight compression test results:
120 EXACTLY on EVERY cylinder. Tested three times.

I will do a leak down test sometime this week if I get a chance.

My questions:
Do cams with a duration such as mine lower the compression test results?
Will a tired/slow starter affect the results?
-8in/hg seems excessively low to me, is this correct though?
When I changed the valve springs I didn't bleed the lifters or anything, will this cause low compression test results?

Thanks in advance to those who help!
 
Last edited:
Try bleeding the HLAs, when the cams are removed, they pump up a touch.

When the cams are installed back in the head, it may cause the valves to crack off the seats a touch lowering compression.

Also verfiy your timing belt marks to make sure you are not a tooth off
 
Try bleeding the HLAs, when the cams are removed, they pump up a touch.

When the cams are installed back in the head, it may cause the valves to crack off the seats a touch lowering compression.

Also verfiy your timing belt marks to make sure you are not a tooth off

I should have mentioned timing is dead on, that was my first check.

I will try bleeding the lifters soon, do I just follow this write up?
http://www.dsmtuners.com/forums/articles-engine-fuel/265060-how-replace-lash-adjusters-lifters.html

If so, I don't have pry bars (STUPID NOOB!) so I'll have to grab some tomorrow and give it a shot.
 
I normally put a battery charger on to charge battery up between tests which keeps test results consistent. Example, no charger I got 140psi then 135, 130, 125. Something scary like that. Then retested with charger and same time between tests, I got 150psi +/- 2psi.

Cam overlap will effect test results but I'm not sure about your cams.

Go to the compression test / leak down testing thread made be Calan for more info on that
 
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