Ok, here's the deal. If you guys can figure this out then you da bomb!! I have a 92 Camaro RS TBI with a CRane Compucam 2031 and 1.6 ratio rockers and other mods. The factory timing setting should be around 6 deg I believe BTDC. I've lined up the timing marks at the crank and cam gears and double checked it and also put the distributor back exactly the way it came out using reference marks. When I set the timing with EST disconnected, the engine seems to run it's best at 16 deg advanced!!! Then when I plug the EST back in,the ECM advances even further to aroung 30 -35 degrees. This seems like a crap load of timing for this engine. Now here's the kicker, I just swapped in a TPI from a 91 transam 350 and after putting everything back together I cranked the engine and it sounds like the timing is WAAAYYY off without backfiring and it won't start. I put the distributor in(again)the way I took it out using reference marks. Is the timing I used for the TBI too far advanced for the TPI? Am I off a tooth on the distributor or what? This is really discouraging.

 

Several things to consider:

1. Your balancer's inertia ring has probably slipped. I don't know whose bright idea at GM it was to put the timing mark on a piece that's only loosely associated with the engine itself by a blob of spooge; but I hope they're long since retired. If you want to check the accuracy of the marks, find #1 TDC with a dial indicator or something on top of the #1 piston, and see if the timing marks line up.

2. If you've changed your timing cover but not the balancer, there's a good chance that the mark on your new cover isn't in the same place as the OE one.

3. You've modified the motor. Now its ideal timing curve is different from what it used to be. Even if you put the ignition timing back to where the factory calls out for it to be, the motor won't run its best; for that matter, it's almost certain that the factory timing isn't where the motor ran its best even when it was stock, since the factory's spec is based on alot of things other than what runs the best (particularly emissions, but also compatibility with an enormous range of operating conditions).

4. TBI vs TPI is not an issue. The parts that are involved are the same, and the spec is the same.

First thing to do would be to find out if the timing mark is accurate. If it's not, your timing light is worthless, and so are the "specs". Then if you get the timing set to the "spec" and the motor still wants some other timing curve, it's time to do some PROM burning.

 

Thanks for the reply. The balancer is a fluidampr so I don't think it's slipped any but I will check. The engine has been modified. I'm using a Pete Jackson gear drive so there's no chain stretch issues.

 

Chain stgretch wouldn't be an issue anyway. You're adjusting the dist to the crank, so it doesn't even matter what the relationship of the cam to the crank is; you adjust the ignition timing "around" that, so to speak.

Your balancer is probably set up for a different timing mark setup from stock. In fact, I'm almost poisitive that it is. You can verify this with a dial indicator as I mentioned. So it's the same sort of situation as changing the timing cover.

Your car would be faster with a chain than with the gear drive.

 

Would an engine still start if the distributor was off one tooth?

 

there is no such thing as "off a tooth" as far as a distributor goes

 

true that because you "chase" the timing by turning the distributor cw or ccw. many people have different methods for finding TDC which looks like what I'm going to have to do in this case. In everyone's opinion, which is the easiest and most effective way to go about doing this without having to remove the water pump and timing cover?

 

its hard to tell at what mark it will run best at until you try them,like they said above basicly the stock marks are only going to give you a starting point,mine has tons of mods including big cam,1.6 rockers,etc etc.and my timing is best at 12 degrees it starts great doesnt knock but I only run the best gas too..good luck with it