350 loss of power

[C101971]

I have run into an issue today, I was driving my truck, 71 GMC c15, 350 4 speed. When I noticed a loss in power, big time. Thought it was vapour lock but I pulled over, checked the distributor connections, they were all good. Spark plugs seem alright. Bit it was also making this God awful noise coming from the water pump I think. It sounded very different, liquidy sounding. But I had no power, rpm was bouncing everywhere. Timing seemed fine, just did the timing chain last week and it ran fine after, till now, she is acting up all the sudden.

Any ideas?

[Steeveedee]

It is possible that the bolts holding the gear to the cam came loose. I won't even ask for an audio clip.

[C101971]

Originally Posted by Steeveedee

It is possible that the bolts holding the gear to the cam came loose. I won't even ask for an audio clip.

Had to drive her home, she ran very rough then after a few minor highway speed she jerked a bit and was driving like new again. Now I'm thinking the fuel was just too hot maybe? When the problem came it was backfiring Alot when I took off the gas, now it went back to normal, no backfire. I think it might be a fuel issue now, what do you think?

[cleszkie]

Backfiring out the exhaust or out of the carb? I would check to see that the distributor hold down bolt is tight and that the distributor is not able to spin. I would also pull the valve covers and check your valve lash, rocker arms and push rods to make sure a rocker didn't partially unseat from a push rod and then fall back into place. The OEM stamped steel rockers have a habit of doing that if they are not adjusted properly, due to the lack of push rod retaining ridges. This usually results in a bent pushrod.

[Steeveedee]

Originally Posted by C101971

Had to drive her home, she ran very rough then after a few minor highway speed she jerked a bit and was driving like new again. Now I'm thinking the fuel was just too hot maybe? When the problem came it was backfiring Alot when I took off the gas, now it went back to normal, no backfire. I think it might be a fuel issue now, what do you think?

If it is running fine now, it's definitely not the cam bolts coming loose. I have no idea what it could be at this point.

[Coley]

You did the timing chain....did you replace the original plastic timing sprockets?
These should always go hand in hand.

All Good
Coley