low compression causes on my setup

[yourmomsrps13]

Im about to rebuild a spare CA i have because my current CA has low compression about 70-50-90-60 but here is my issue...My motor pulled hard and was fast with a t25-12psi + great tune then i installed HKS 256 8.5 cams went and tuned the car and pulled a couple of 8,000 rpm hits to make a safe tune. after tuning i let her cool down some and check the oil and notice im about 1.5 quarts low, so i added oil and then a few mins later im seeing white smoke out the exhaust and its alot.so im thinking it the turbo so to check i pull the exhaust manifold off and start for a second to see if the motor is smoking......i dont see any smoke, so i buy another used t25 (off a friend who never saw smoke), install it and again the same amount of smoke, once again i remove the manifold and install another t25 with less shaft play....still smoking but not as bad, so i do a compression test and come up with those above numbers. so my question is..... is it my rings or in the head and also what would you do to further check my problem?Thanks guys
Modified by yourmomsrps13 at 3:10 PM 3/24/2008

[dattodude]

Changed cams means you've played with timing belt.

If you didn't reinstall properly, it could have jumped a tooth or two, and lets hope it didn't jump 4 or 5 because then you might have bent some valves.

256/8.5 cams shouldn't change your compression too much.

Pull the front covers off, and triple check all 3 marks at top dead centre cylinder 1.

[yourmomsrps13]

the timing belt never cam off the cams, plus it runs and drives good still

Im wondering if the valves are not sealing correctly, hmmm or maybe my rings are just done
Modified by yourmomsrps13 at 2:42 PM 3/24/2008

[BACARDI_DWB]

white smoke normally means head gasket.

[r34 gtr]

You revved it to nine thousand?!?! WHY! Why would you do that?! *cry*

[yourmomsrps13]

just talked to my tuner who reminded me i was tuning to 7500 rpm and im not sold on the rings being bad, so what could i have done in the head and how shall i check it out?it hit almost 8,000rpm once. i'll edit my original post....its been a whole season since it happened so i forgot what i was at
Modified by yourmomsrps13 at 3:10 PM 3/24/2008

[r34 gtr]

Did you try the oil-in-cylinders trick to see if it really is the rings? If you haven't, go do it.

[slo]

That low of a compression and white smoke out the exhaust....

Headgasket

[yourmomsrps13]

You revved it to nine thousand?!?! WHY! Why would you do that?! *cry*

edited, sorry to scare you haha. i need to go do that but im far away from my car right now, next week i will try that ASAP

[yourmomsrps13]

That low of a compression and white smoke out the exhaust....

Headgasket

there wasnt any smoke till i added oil, also its low across the board .... ugh maybe it is the rings

[r34 gtr]

Its not like rebuilding a ca18 takes more than a weekend. Buy the stuff to do it, and rebuild it when you are with the car next. It should cost you under $300 for a gasket kit, rings, bearings, and maybe a new OEM HG. This is of course if the head isn't f'ed. If that is the case, use the head off the other motor.

[yourmomsrps13]

Its not like rebuilding a ca18 takes more than a weekend. Buy the stuff to do it, and rebuild it when you are with the car next. It should cost you under $300 for a gasket kit, rings, bearings, and maybe a new OEM HG. This is of course if the head isn't f'ed. If that is the case, use the head off the other motor.

i need to stop being lazy and stop worrying about rebuilding it myself, i have a Nissan OEM full gasket kit with head gasket im just having a hard time finding Nissan rings, bearings, head studs and oil pump for a decent price.

[r34 gtr]

I just replaced the rings, gaskets, and bearings. You can rebuild the oil pump, just make sure all the o-rings in it are nice and soft, and not brittle and cracked. Get some ARP head studs, or go to the stealership. I got my rings from Advance Auto. Total seal chromoly rings for ~90, which is rough but I needed them the next morning and didnt have time to wait for cheaper ones.

Actually, I don't know how in-depth you can get rebuilding the oil pump, but you can change out a few 0-rings. I did and the thing works fine. Oil pressure is a little lower than some peoples, but screw it. The way I see it, people don't want high blood pressure, why should my car? right? Just means she lives a laid-back lifestyle and will probably live longer because of it.