1978 gmc sierra runs rough
 

Hey first thread ever new at this just got a new dumpster on wheels 1978 gmc sierra that runs in neutral or in park and can rev it up with fairly clean acceleration and is able to go to high RPMs .But when in drive engine skips and hiccups but slowly increases speed ..Transmission shifts normal but tends to pop into 2nd gear a little i think only because of trying to accelerate heavy..Also if the vehicle is in reverse the transmission seems normal and vehicle just runs rough.. Help,Please and Thanks Brandon

A few months back I picked up a '79 SWB as resto project. In the meantime I have been working at getting it roadworthy so I can use it. It was off the road for a long time and when I got it, it ran poorly. There was an off the shelf Holley carb and air-gap intake which I removed and replaced with the stock stuff from a donor truck.The poor running persisted until I discovered the timing was retarded due to the timing cover/timing tab being replaced at some point with the wrong pieces. The engine in question is a reman 350 that is pretty clean inside. I have no history on the engine. I think the truck was restored 15 years or so ago and was let go downhill after that.
Tutuapp 9apps Showbox