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914World.com _ 914World Garage _ compression testing questions

Posted by: freezing14 Dec 10 2004, 07:58 AM

Ok got the frigging engine out because of those back fire,, remove the heads, , clean everything , lots of oil everywhere, and i do the compression test, here is the result

i did the test with 5 revolution on each , they all got the same result ( thats good) here my question

1st revolution 90 psi,
2 nd revolution 120 psi
3 rd revolution 155 psi
4 and 5 th revolution 155

is this ok , or do i need to change the rings or i am ready to

Posted by: Bleyseng Dec 10 2004, 08:12 AM

R U doing the compression test with the engine warmed up?
Try squirting a little oil into the low cylinder and re test. If it stays down then you have a valve problem. ie -not seating or burning.

Geoff

Posted by: scott thacher Dec 10 2004, 08:15 AM

but before you do the test again do a valve adjust, and did you have the spark plugs out on all cylinders

and i though oil in the cylinders was for rings not valves

Posted by: freezing14 Dec 10 2004, 08:16 AM

a little interpretation issue here

cylinder 1 revolution 1 90 psi rev 2 120 rev 3 150 rev 4-5 150
cylinder 2 revolution 1 90 psi rev 2 120 rev 3 150 rev 4-5 150
cylinder 3 revolution 1 90 psi rev 2 120 rev 3 150 rev 4-5 150
cylinder 4 revolution 1 90 psi rev 2 120 rev 3 150 rev 4-5 150

it says in the book with the compression tester that you need to use the same number of revolution testing

Posted by: Bleyseng Dec 10 2004, 08:21 AM

So 150 on all cylinders thats great. Hmm, you running carbs? or FI.

Posted by: scott thacher Dec 10 2004, 08:21 AM

thats

put the motor in and

Posted by: freezing14 Dec 10 2004, 08:26 AM

I will be running FI unless it buzz me off, then I wil carb it,
the 150 was acheived at the 3rd revolution so it would be ok , May be i can drive it before we have snow on the ground definitively,,,,,

Posted by: Jake Raby Dec 10 2004, 09:56 AM

Also, did you test with the throttle at full open?? If not the numbers can vary due to not getting very much air into the chambers.....

Posted by: freezing14 Dec 10 2004, 10:04 AM

I did the test with no intake runner,,,, so would be considered as the throttle open??????, I just wanna made sure it was OK before I put it back togheter and in the car

Posted by: Rhodes71/914 Dec 10 2004, 11:07 AM

I think you should be happy with those results. Put it in and drive before the snow flies. Wish I was at that point, couple of weeks maybe.