Went to the track last night to try and get the times back to where they once were.

Got two practice runs, and raced three bracket races. Driving home, I put my foot in it a couple of times to test the kickdown from OD to third and back. On the offramp, I got in it and it coughed and popped through the carb. A first.

I'm on a side street, about a mile from home, and while in 2nd gear, I accelerate, it pops louder and dies. It wouldn't start again, and I had to get AAA to tow me 1 mile home.

Today it still won't start and backfires through the carb. I got fuel, the carb looks fine, the Crane Fireball has the LED on (can't get a pop w/o spark)

All I'm thinking is did the distributor go nuts? Or did a rocker arm fall off (although the engine when running sounded fine)?

Help!

Any chance you have the factory nylon toothed cam sprocket?
Crank the engine with a timing light on it and see where the timing is now.
If it's retarded a lot, bring it back up, check by cranking it with the light on it.

If it's still bad, suspect the cam sprocket jumped timing or something came loose in there.

A friend had a similar problem, turned out it was a broken timing gear (nylon). He did some valve damage and divoted a piston with a valve. Pull your valve covers and crank the engine over while watching the valve train. If you don't have rocker arm movement, there's a problem either with the timing gear, the chain or with a broken camshaft. If there is movement, it still could be a bad gear or chain, which has jumped a notch.

One other simple thing to check is the distibutor, making sure it hasn't popped out of the block, due to a loose bolt.

If the above are OK, I'd bring the crank around to the #1 firing position, using the timing mark. You can watch the rocker arms as you crank the engine around -- the Intake on the #1 cylinder should have just closed as the timing mark comes to TDC. The point here is to verify where the distibutor is in relation to firing on #1. The rotor should be pointing to #1 on the cap.

Good luck!!

IMO, I don't think its a broken timig chain or stripped sprocket, he's replaced the camshaft and hopefully replaced the nylon sprocket with a steel set. However, this doesn't mean it couldn't have stretched and jumped a couple teeth, a low compression reading, under 100 PSI, will show this event, at least it does for a Buick 350.

SBC's are interference engines. Camshaft stops turning, valves get bent which will ruin your day.

If the engine still cranks, this is good. If it is making comression in all 8 cylinders, this is better. If it making alot of compression, say 150 PSI, this is best. I would do as the others suggested and check for a moved distributor. If it hasn't moved, then I'd look for chain stretch. One can turn the engine by hand to the timing marks and then rotate backwards to feel the amount of slack in the chain. Anything over 8*, chain is stretched a goodly amount.

If you put the timming pointer on tdc and get there in only one direction then go the other direction and see how much play is in the chain by comairing it to the rotation on the crank shaft in degrees. Remove the dist cap to see when the rotor moves when turning in the oposit direction thats when you stop and check rotaion movement at the crank. It may be easyer to move the engine by hand if you remove the plugs prior. No more than 3 degrees is acceptable. I had one with 8 deg.and it still ran! the chain almost fell of the sproket into my hand without touching sproket.

Hey Guys. I just got home from work and am heading out to investigate this problem. The suggestions so far are great. There definitely is NO nylon timing sprocket in there. Although I didn't replace the timing set last August, it was a double roller from when the motor was rebuilt 10 years and 23k miles ago - so not overused by any means.

Timing seems to be where I'm going to look first.

Well, the verdict is in.

I started by cranking the engine over by hand and found TDC on #1 (adding in 12* for the advance) and the timing was off by nearly two plug wire positions.

I lift and set the dist in the right spot and try turning it over. It doesn't pop, but won't even catch a little either. Seems like no spark (or trigger for my Crane Fireball ignition).

Checking the magnetic pickup again, it spins a little while the dist is STILL INSERTED. We lift it out to inspect and...

Either my buddy and I did something wrong when we changed the cam last August, or something caused the camshaft to jam or walk because half the distributor gear is shorn off on one side.

It's pretty much a pull the motor, drop the pan, pull the cam, inspect lobes and distributor gear, etc..... OR... zz430 crate motor for Father's Day!!

There'll have to be serious discussions with the wife about the direction I go with this.

Thanks loads for all the support, advice, and theories with this problem. I think as it turns out, you are all to be commended for diagnosing this problem right to the root cause.

Thanks again. Ozzie