I've been working on a 1990 Firebird. I had an issue a few months back work the cat plugged up while i was driving, unaware of what had happened at first i managed to get drive it to my little shop to work on it. It was bellowing black smoke and it had gotten so hot on the passenger side it melted the knock sensor and plug and melted a few different vaccum lines. I cut the cat off and it was running suitable. With a 176k on the ticker i decided to pull the motor and go through it and freshen it up. I aquired a haynes manual. I went through and adjusted the rocker arms according to the manual. I replaced the intake gaskets, oil pan gasket and exhaust manifold gaskets spark plugs, wires distributer cap and rotor. I scavanged a new knock sensor plug and bought a new knock sensor. I fixed a few burnt wires and back in it went. The manual said to adjust the rocker arms with #1 on TDC compression with the timing mark on 0. It took me awhile to notice all the grooves in the harmonic balancer. I used the groove that was the biggest?? It was the only different one of the three. I redropped the distributor and I believe it to be alittle bit off. The car cranks over like a raped ape, its getting fuel and spark. It acts as tho it wants to start but as soon as you let off the key it dies. I've been reading up on adjusting the timing. Unhooking the wire on the passanger side and setting it to 10 degrees BTDC. In order to properly do the timing I would need the car to run......any suggestions on what i need to do to at least get the darn thing to run. thanks Clint

 

take the spark plugs out.. use a suitible tool like a piston stop or a wood dowl.. run nr 1 up to tdc slowly. then check marks. rotate to base timing i think is 10 btdc i think.. look in the manual.. you could just be 180 degrees off. just easyer to pull the distributor and recheck the timing. im betting its 180 out. these cars are a bit tempermental they don't like starting if not set close to 10 btdc like 8-12.
i made the same mistake once. a bit expensive. timing was 180 out and backfired through the intake. melted the vaccum tube going to the throttle body in 3 places..

 

When you turn the engine by hand, and your piston in cylinder #1 is in TDC, You distributor rotor should point to the terminal for spark plug number 1. You can feel top dead center by the air that is coming out of the spark plug hole as you turn the engine You can have an assistant crank it for you a little to get it close, and then use a socket on the crank bolt to turn it by hand. Use a sharpie to mark the position of the distributor cap terminals onto the distributor, so that when you take the cap off, you know where things would line up. That should get you close enough to get her started.
Also, I know that this sounds very simple, but make sure that all of your plug wires are connected to the plugs on the proper cylinders. It is easy to make a mistake sometimes and have a couple of them miss matched. Good luck.

 

This is most likely the issue. In this thread there are a couple of posts on how to adjust the rockers properly.

https://www.thirdgen.org/forums/v6/4...-5-timing.html

RBob.