Engine Performance problem
1989 GMC Jimmy V8 Four Wheel Drive Automatic 180000 miles
I have a full size Jimmy with a 350. I had a cracked head and blown head gasket so I replaced the cracked head, had a valve job done and put it back together. I was careful not to mix push rods and rocker arms and such. I observed all the torques specs. I replaced the distributor cap, plugs, and wires. I changed the factory exhaust to headers (did not put O2 sensor in headers) and did away with the smog pump hoses. When I crank the engine it seems to run nicely, even when I rev the engine, but when I drive it with a load on it it backfires thru the exhaust and lugs down. I've played with the timing from 0 (setting called for on the engine compartment) to 8-10 BTDC. I replaced the fuel filter but that had minimal effect, if any at all. It's nice to have something that sounds good in the driveway but it would be nicer to have it run down the road.
Wednesday, March 4th, 2009 AT 8:27 PM