I am trying to set the timing on my 90 GTA with a 5.7 TPI. First I disconnected EST wire and hooked the timing light to the #1 spark plug wire. When the car is running and I aim the light at the timing tab and balancer, no matter how far I turn the distributor, I can never see the timing mark on the balancer when the light flashes. I even ran a line of white paint in the groove to help me see it. I remembered reading a post about how you can make the #8 cylinder the #1 cylinder(not on purpose,but if you remove the dist. and it does not go back in right) Anyway, with this in mind, I hooked the timing light to the #8 wire. Now I could see the timing mark, so I set the timing to around 8 degrees BTDC. The engine is running pretty smooth at this point, now I plug the EST wire back in, try to restart the car and it wont start and backfires like the timng is way off. At this point, I just put the dist. back in the position where the engine idles smooth and stays running when put in gear. Now again, no timing mark when the light flashes but the timng has to at least be close because it runs now. BTW, I did not just decide to go out and adjust my timing. I put a new cam in it, new timing chain & gears, and a few other things. Then I messed with the dist. just to get it running, but I need the timing to be right, not just assume it is close because the car stays running.

 

Just to make sure you have the right wire and distributor orientation.

Did you degree the cam installation?

 

The wires are on right, and I did not degree the cam. I did not think that you HAD to degree the cam, and it was just done to make sure the cam was manufactured to spec. Will it make a difference if I bring the rpm up to 2000 (Haynes manual says adjust it at 2000) instead of idle,which is about 750? I was able to see the mark, but it was right below the waterpump snout at about 12:00.

 

You should be able to set it at idle. I would still double check your plug wire routing. It is very easy to get mixed up. IF that doesn't work I would pull the distributor and re install it making sure the rotor points to #1 plug wire while the balancer mark is set to zero on the timing tab.

 

*I was able to see the mark, but it was right below the waterpump snout at about 12:00.*
When it is like this, it idles pretty smooth and usually will stay running when put in gear. Should I pull the distributor out and drop it back in a tooth or so over in the clockwise direction? When I turn the dist. clockwise the timing mark(on the balancer) moves closer to the timing tab, but the idle starts dropping if I move it too far and I can tell that it is going to stall if I keep going. I have also checked and rechecked the wires for propper order, new MSD cap & rotor, new dist..

 

Does your balancers TDC mark line up with the true TDC position?

 

I just thougt of something else, this car has a Hypertech chip in it. Do I need to take it out in order to accurately adjust the timing?

 

As far as I can tell, I pulled all of the plugs today and turned the crank to what showed as TDC on the mark and balancer and the rotor was pointing toward #1. I was by myself, so I did not have someone to feel for compression at the plug hole, but I put a screwdriver in and could tell the piston was up. If it was at complete TDC would you be able to get a screwdriver in the plug hole? BTW, this is not the stock timing chain cover, it is a chrome Mr.Gasket with the timing tab that attaches to the bolts. I want to put my stock cover back on because I have a bad oil leak at the pan even with a new pan gasket. I have also read that these covers are crap and prone to leaking, of course I read this AFTER I put it on.

 

Will the Hypertech chip affect setting the timing?

 

No the Hypertech chip will not affect the static timing.

No degreeing the cam will not afect the static timing. You're using the timing light to compare the spark to the crank; if the mark shows that it's firing at 0 or 4 advanced or whatever, then that's what it's firing at, regardless of where the cam is.

Turning the dist clockwise retards the timing.

"Right below the water pump snout" is where the stationary half of your timing mark is supposed to be. If it's not there, somebody probably stuck some aftermarket timing cover on it, probably a chrome one I would guess, probably the type of person that's easily distracted away from important things by shiny things. If you really want a timing mark, you need to put a factory one back on there; or get one of those tabs you can bolt on somewhere, and find #1 TDC, and mark it on the balancer.

 

"BTW, this is not the stock timing chain cover, it is a chrome Mr.Gasket with the timing tab that attaches to the bolts. I want to put my stock cover back on because I have a bad oil leak at the pan even with a new pan gasket. I have also read that these covers are crap and prone to leaking, of course I read this AFTER I put it on."

Originally posted by me, ,I just took it for a drive and it seems to be running pretty good. No more stalling or backfiring. When I get the stock cover back on I will recheck the timing. Thanks for the help everyone.

 

Ah, I missed that I guess, sorry about that.

Those are 2 good reasons not to use an aftermarket TC, expecially a chrome one: leaks, and no/wrong timing mark. The third good reason is the fast that the chrome invariably has pinholes, the base metal underneath rusts, and blows the chrome off in sheets after just a few months, which sort if negates the reason for using a shiny one in the first place.

Computer-controlled engines use the timing tables in the chip to create the correct firing time. However, the ECM has no way of knowing where the static timing is; all it can do, is create an "offset" from wherever the static is set to. So if you don't have a timing mark, you're left with basically timing to where it runs the best.... which is what you're really after anyway, not just duplicating the "factory spec", which is WRONG to begin with if you've changed the cam (or other engine internals) significantly. It's arguably WRONG even for a stock motor; it's chosen for a number of criteria, including fuel quality, altitude, ambient temp, driver preference, emissions, gear ratio, vehicle weight, and on and on and on; if you don't drive your car at sea level but rather only at 6000', or if you're in Florida not Minnesota, or any number of other of the "boundary conditions" for the factory spec don't apply to you, then that might not be the optimum timing FOR YOUR CAR.

 

And even with an aftermarket timing cover and Chinese timing tab, having the base timing at the 12:00 position is far too advanced for it to be correct. If that is where you get the best overall idle and operation, that is indicative of cam timing that is incorrect (which is why i inquired about degreeing the cam in the first place).

Not to argue with RB's expertise, but in my experience, the "best" static or base timing is dependent more upon valve train events than crankshaft and piston position when at idle or under light-moderate loads. Getting the base timing set "by ear", or vacuum gauge, or whatever method other than a timing light typically reuslts in a setting that is more related to valve timing than piston travel - to a point.

Missing the timing chain installation by only one tooth will alter the cam/valve timing by almost 18°. Couple that with the approximately 10-15° advance that most SBCs tend to like at idle, the 4° valve timing advance "put back" into the cam grind by most aftermarket suppliers, and the correct position for the timing tab on your factory cover, the timing mark would be near the described 12:00 position at "best" operation.

I've seen this same scenario many times before - Where the timing set is installed incorretly, and the "optimum" spark timing is far too advanced from typical specifications, yet overall performance is not as expected, and operation is frequently accompanied by some backfire under load.

I could be mistaken, though.