Hoping I don't have a head job on my hands

[xxvengxx]

I just got my z running again. But runs real rough and blow ing white smoke out the tailpipe. It had been sitting for a year and a half. I just finished a complete timing belt job ( cam seals idlers tensioner water pump thermostat etc) and replaced all the fuel injectors (all new fuel hoses filter). Replaced the injector o rings too. The car ran rough from cylinder 4 for awhile. I had oemed the injectors and found that cylinder had high resistance. The others were fine. I don't remember the exact numbers. I also had a Nissan dealer look at it and they said injectors. They did a compression check and said it was OK. now I know I have a few vacuum leaks which I will be addressing next week. I will also be pulling the spark plugs testing the coil packs and injectors as well as setting the timing and doing another compression check. Also I am pretty sure the timing belt was set up properly but after I do everything else I will tear it back down to make sure. Any other ideas suggestions?

[Ace2cool]

Track down those vacuum leaks. That's why your car is running like crap. If the compression is good, the head is good. Why are you even considering a head machining job?

Also, if you machine the head, go ahead and rebuild your engine. The added seal/compression from the machine job will more than likely force air/oil past the piston rings and cause the car to smoke very badly afterwards. Do one, do both.

[xxvengxx]

Sorry, I mis spoke, If I had a bent/ burnt valve I would look into replacing/ rebuilding the head, which of course I would rebuild the other head as well.

[xxvengxx]

oh, I was curious about something, when I put my timing belt on (was a b*tch to get all five marks lined up) but when I was able to get it set up, I had everything lined up (lines on the belt with marks/dimple on sproket and then back to the backing plate) I had to rotate the driver cams a hair back to get the belt on properly and then back to match the backing plate. but once i released the tensioner it no longer matched the backing plate on the driver side only. The belt was still lined up across all four cam sprokets. I spun the motor all the way around and felt no contact being made. I had read some of the things you had said on other peoples posts saying thats all that mattered so figured I was good.

[Ace2cool]

Yeah, backing plates don't matter at all. They're simply there to help you find TDC. Past that, you only need concern yourself with the cam gears and timing marks on the belt.

And if the engine still compression checks good, then the only problem you have is vacuum leaks. If there was a bent valve, the compression on that cylinder would effectively be 0.

[t.mcginley.jr]

Sorry, I mis spoke, If I had a bent/ burnt valve I would look into replacing/ rebuilding the head, which of course I would rebuild the other head as well.

Basically if you have to rebuild the heads, you might as well rebuild the bottom end too while you're there. New parts don't mix well with worn/older parts like Ace said. Also since you think you may have a bent valve, you should check the pistons to make sure there isn't damage