timing issue?

[Jazic3.4]

I just put my engine back into my 92 Z34 after its been out for about 3 months. The engine runs fine at idle except it has no torque/power in motion? If I floor it, it backfires a bit and when it actually kicks in, the motor roars but the car hardly goes anywhere? I may have screwed up the timing. In the pic I posted, you can see the rear cam bank. The yellow markings are factory. The white ones are thr ones that i created because this is where the sprockets were positioned when i took it apart initially (when the engine worked fine) So when I put the motor back, i figured i would use the factory markings. I think I should have stuck to the white markings. Could this much of a tooth difference affect the performance of the vehicle? The front bank are ok. They were right on the yellow markings before and after the engine removal.

[SappySE107]

RE: timing issue?

Thats the problem. You used some marks on the cam gears instead of the cam flats. How did you do the timing without pulling the gears off the cams to begin with? The cam flats don't change, which is why I tell everyone to ignore any marks made on the gears themselves. Plus, with the belt stretch, your marks are theoretically off anyway if by some chance the yellow marks were accurate.

[Jazic3.4]

We set TDC. We then bolted the cams on. With a ratchet, we rotated the sprokets until the yellow teeth lined up. We did the same with the front bank. We then locked the sprokets in place with a hold tool, wrapped the belt on and rotated the crank for a full cycle. The markings still lined up and we then reassembled the rest of the engine.

A GM tech told me that even if you manually time the motor this way, and you don't line the markings up properly, the computer will adjust everthing to proper spec. So he seems to think that I have a faulty computer.

This kind of makes sense because i had a VSS problems last year. There were no actual fault codes. The spedometer wouldn't work and car ran like crap whenever this happened. It had no torque and no power. It was as if it ran on 4 cylinders. I replaced the VSS but this still happened. So it could be a computer problem. What do you think?

[perfimage]

That GM tech is full of it. The computer cannot change cam timing, it is physically impossible. Like sappy said, it is possible that the marks are good, but the only way to properly time these buggers is to follow the directions and ignore ANY marks except on the balancer and the front cover that are referenced in all the walk throughs.

It is entirely possible that you have all 4 flats up which is a common mistake, and given that you lined all the yellow marks up, you could very well have disregarded the position of the flats. You have no idea at what point the original engine builder put these marks on and if he marked each bank at separate times (like after rotating the crank one rev after timing the first bank), this would definitley be your problem.

Unfortunately the only way to check/repair is to start pullin it apart. Start with the upper IM, (plenum) and remove both cam covers. IGNORE flats and marks until you have the balancer mark and timing tab lined up as shown in the walk through. THEN check to see that the flats are up on ONE BANK. Then spin the crank one rev. At this point, the flats on the opposite bank should be up. If at ANY point all 4 flats are pointing up, your timing on one bank is off 180 degrees. If one set is up and the other is down but the flats don't line up, then you were done in by the old timing marks. Either case, you will have to go through the whole timing process again, this time hopefully correctly.

Good luck doing this in the car, them cam cog bolts are a BITCH and removing the cogs on the 92 is even worse.

RED

[Jazic3.4]

So what you want to achieve is when the balancer mark and timing tab are lined up, you want one bank to have flats up and the opposite bank to have its flats down.

Where can I get the cam flat tools used in photo DCP_2046.jpg of the cam timing picture walkthrough? How many would I need and what would the part number be for this item?

Thanks

[SappySE107]

I had the same issue earlier this year. It was a bad memcal, not ECM that caused my VSS to stop working and the car to run like ass.

Its probably the kent moore tool in the pic, which is like 100 bucks for a set I believe. There are directions in the same area of the site for making your own hold down. THere is also the tool I sell for 80 shipped that allows you to set whatever timing you want. I don't recommend buying the kent moore kit other than the cam gear puller for the cam 91-93 setup (unless you can get a different puller to work) and the cam gear holder for loosening the bolts.

[perfimage]

Correct, then once ONE BANK is correct and the cogs tightened, you turn the crank ONE REV, lock the cams down with the cam hold down tool and install lock rings, bolts and tighten the cogs down.

Take a look at the maintenance section. You will find all the information you need there to make your own. You might also be able to rent them or borrow them from someone but unfortunately that wont be me. The first time I loaned tools out for this job through this board was the last time. They came back totally jacked and he hasn't replied to any messages since I asked him what he did to the tools. Don't even think of seeing if your local Autozone or other chain parts store has one, they will give you a stupid look and some times even say "What are you lookin for?". Your best bet is to make the tools or hit e-bay and possibly find them a little cheaper, or if you have a REALLY GOOD buddy that works at a dealership, you might be able to get them to loan them to you.

Just remember, if you do make the hold down tools as shown in the maintenance section, they are only for holding the cam flats in line, NOT for keeping the cams from turning while you tighten and torque the cog bolts.

Sorry, I dont know the part number of the cam hold down tool but you will get raped if you buy it. The entire set runs something like $230 from Kent-Moore which includes the hold down tool, the cog puller, and cam holder (for tightening and loosening the cog bolts).

Good Luck!

RED