dry compression test results
Thread Starter
Joined: Oct 2003
Posts: 1,164
Likes: 2
From: Frankenmuth, MI
dry compression test results Did a compression test tonight on my motor. No problems with it and it runs strong, some oil consumption but also have a small leak that contributes to that. Motor has almost 130k on it.. I think these numbers are good, but not sure.. i used a super old snap on kit that i borrow from a friend so the gauge could be slightly off..
Cylinders 1 and 3 were the lowest with #1 around 163 psi and #3 around 165 psi.. all other cylinders were sitting 170-175psi.. i still need to check cylinder 8 but didnt get to it tonight.. thats not more of a 10% difference but pretty close..should i be concerned to swap heads and cam on this motor? I could do a leak down test but not sure if its necessary? I have seen anywhere from 160-220 being "normal" in old threads and not sure what to believe. I did crank 5-6 times with the throttle wide open. It seemed to stabilize on the gauge by the 6th crank and would hold the pressure. The motor was also cold and about 40 degrees in the garage if that makes a difference?
Thanks for any input!
Cylinders 1 and 3 were the lowest with #1 around 163 psi and #3 around 165 psi.. all other cylinders were sitting 170-175psi.. i still need to check cylinder 8 but didnt get to it tonight.. thats not more of a 10% difference but pretty close..should i be concerned to swap heads and cam on this motor? I could do a leak down test but not sure if its necessary? I have seen anywhere from 160-220 being "normal" in old threads and not sure what to believe. I did crank 5-6 times with the throttle wide open. It seemed to stabilize on the gauge by the 6th crank and would hold the pressure. The motor was also cold and about 40 degrees in the garage if that makes a difference?
Thanks for any input!
Thread Starter
Joined: Oct 2003
Posts: 1,164
Likes: 2
From: Frankenmuth, MI
Ok thanks, i wasnt sure if 1 and 3 were getting a bit on the low side or not.. i have seen so many mixed numbers on here searching that it makes me question it.. i guess sticking to the 10% rule gives me the green light as long as #8 checks out good.
Im going to send off an oil sample next to check for any excessive bearing wear and see what i find from that.. im guessing it will be fine with my oil pressure still being within spec, but figured it wouldnt hurt to check for $28..
Im going to send off an oil sample next to check for any excessive bearing wear and see what i find from that.. im guessing it will be fine with my oil pressure still being within spec, but figured it wouldnt hurt to check for $28..
Thread Starter
Joined: Oct 2003
Posts: 1,164
Likes: 2
From: Frankenmuth, MI
Got all cylinders done now..
1-163 2-170
3-168 4-175
5-175 6-175
7-175 8-160
That was 5 to 6 cranks at about 36-40 degrees in my garage.. i didnt think of temps effecting pressure.. i question cyclinder 8 and 1 the most.. are they within spec to move forward with the build?
Any thoughts? Hard to say if the gauge is accurate.. kit is probably 20-30 years old.. rubber hoses dry rotting and cracking lol.. i noticed around 5-6 cranks the pressure started to level off..
1-163 2-170
3-168 4-175
5-175 6-175
7-175 8-160
That was 5 to 6 cranks at about 36-40 degrees in my garage.. i didnt think of temps effecting pressure.. i question cyclinder 8 and 1 the most.. are they within spec to move forward with the build?
Any thoughts? Hard to say if the gauge is accurate.. kit is probably 20-30 years old.. rubber hoses dry rotting and cracking lol.. i noticed around 5-6 cranks the pressure started to level off..
Thread Starter
Joined: Oct 2003
Posts: 1,164
Likes: 2
From: Frankenmuth, MI
Im hoping silence is golden, ill stick with moving forward with the build.. oil sample was taken last night so ill find out if i have any worn bearings or excessive wear in general. If anyone sees any reason not to move forward please chime in.
