[Garrett.m12]

What I Have Is a 1990 Chevy C3500 Longbed Extended cab 2 wheel drive 1 ton pickup. The other day i had a really bad back fire it killed the engine , i puled over fired her back up and drove her home. The next day on my way to work it did it again but not as bad, except this time it didnt start at all , I had to be pulled home. once i got it home it still wouldnt start,No spark? so i replaced the ignition control module, It started and idled fine after that, after about 10 minutes the truck wasnt running for ****, rough idle and bad miss. so after this i checked compression in all cylinders, driver side had about 70 psi per cylinder and passenger side none whatsoever, checked to see if all pistons were stil moving when engine is cranked over and they are !. so today i pulled the valve cover and intake, nothing out of usual, Maybe i have a blown head gasket? theres no water in oil either.

[cool rockin daddy]

Flattened cam lobes?

[cobalt327]

There's a chance the timing set has given up the ghost. Either by jumping time a couple or more teeth- or it broke the chain completely

The first thing I would do is to crank the engine and watch the rockers. If they're still moving, you need to set the engine to TDC using the timing line on the balancer and the timing tab.

Then remove the distributor cap and see if the rotor is pointing at #1 or #6. Mark the position of #1 and #6 on the distributor BODY, using the cap as a guide.

With the timing marks at TDC, the rotor should be just after the marks you made. If the rotor is pointing elsewhere, suspect the timing set has jumped time.

[Garrett.m12]

Even If It did break the timing chain would it still run? cause before i tore it all down it was running just very poorly i even drove it like 5 or 6 miles before i tore it down, and from what i can see on the cam the lobes arent worn,

[cobalt327]

Originally Posted by Garrett.m12

Even If It did break the timing chain would it still run? cause before i tore it all down it was running just very poorly i even drove it like 5 or 6 miles before i tore it down, and from what i can see on the cam the lobes arent worn,

If the chain was broken it wouldn't run at all. It still may have jumped time. Follow the sequence I wrote above and you will know if that is, or is not, the problem.

If you have the engine apart far enough to see the timing chain and gears, rotate the engine CW as you face it from in front of the radiator to get the two alignment dots on the timing gears as close to each other as possible.

This will be: crank gear dot at 12 o'clock, cam gear dot at 6 o'clock.

If you find that the dots will not align perfectly, you will know the chain has skipped. Plus the chain will be loose, the cam gear may even show considerable damage. The crank gear usually survives this w/o showing anything.

Good luck.