I finally have everything together and I'm getting ready to finally fire up the b18c1 after rebuild. Motor was bored out to 81.5 and honed, new rings. I did a dry compression test and the numbers were 1 - 90psi 2- 170psi 3 - 150psi 4 - 95psi
Is this normal? I haven't started the car?

 

No it's not normal. Compression should be much more consistent. What else was done besides pistons and rings?

 

170 being the best ? AFTER a rebuild something is wrong...you should be pushing 260 +/- 10.

 

Head was cleaned and resurfaced, new bearings, oil pump and gaskets. Just a standard rebuild. Also the pistons are RS Machine ITR. Just about when I was getting to start the car it starts raining out side just my luck lol. My brother is going to come over, and I'm going to try and do a wet compression test to see if there will be a difference.

 

I guess it's just me, but I wouldn't be too concerned given that you haven't even started the engine yet. If those were your numbers after break in, then it's time to worry.

 

the rings are not seated.

test after break in then you can tell if something wrong

 

i would not worry as long as u spaced rings correctly. the rings have not sealed to the Bore yet so you shouldnt have a prob after you put some miles on it. I would be very interested to see some numbers during the break in process.


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follow the break in instructions and follow oil change procedure. it would be interesting for you to do a comp test after each oil change so we can see exactly when peak numbers are reached on a fresh rebuild!


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Check your valve lash.

 

The rings should not lose that much compression even without being seated yet. If the bore, hone and ring/pistons were done and installed properly that should have good compression already. If it doesn't then the rebuild sucks or you have problems elsewhere. Like rocket said check the valve lash its pretty common to have people overlook that and have the valves hanging open too much.

 

Okay so far I've put 20 miles on the motor, Last nights break-in sucked. It began to rain hella hard and I was forced to end the break in not even 15 miles in. Just did a compression test, numbers were: (1)190 (2)210 (3)210 (4)190. Also I believe I have a vacuum leak but I can't figure out were.

 

much better but still not great. did u Adjust valve lash?


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No not yet, still trying to find and fix the vacuum leak. Any advice?

 

what type of tester and is it stock pistons also did you adjust the valves

 

why would you not adjust the valves BEFORE driving the engine?

 

Please adjust the valves, if the head is just back from the machine shop normally they are loose...where the nut will be able to fall off.

 

Sorry to bring back an old thread but I felt the need to update the results of the compression after 1800 miles. All 4 cylinders are at 240psi.