Question : PLEASE HELP! Timing chain skip or bad camshaft?!?

[Braddock]

This truck runs seemingly ok when its warmed up and idling, but when i give it throttle it slows before it picks up, and noise and exhaust comes up though the carb.

I advanced the timing by turning the distributor and the engine started speeding up, I must have turned the distributor more than 25 degrees counterclockwise and it kept picking up(The distributor is definately not in its natural position after this adjustment). And even though it did this, it continued to blow through carb when i gave 'er throttle.

Could the lobes on the camshaft be rounded? or do you think my timing chain is just out a tooth? Its an 86 vehicle and has never had the chain replaced as far as i know Aparently this problem came on reasonably quick. Its not my vehicle, im fixing it for someone.


Basically when i turned distributor far out of normal position, the engine speed picked up greatly, but noise still came though carburetor. If the chain were out a tooth it would explain the distributor working better when turned 30 degrees out and the exhaust noise comming though carb. But what is the best way to know?

[alerored04]

If the timing of the valves was off wouldn't a compression test verify this? Bad overlap etc? I am only guessing so wait for other advice as I am not the most knowledgeable.

[sprucegagt]

Has the distributor ever been out lately? Sounds like it may be out of time.

As a side note. Idle speed will increase when you advance timing. It's completely normal.

EDIT: Wait a minute. You said truck. Would this truck happen to be a S10/S15?