Problem getting a 1979 GMC 350 running

[stewy4344]

Have a 1979 GMC 1500 with a 350. It sat for 18 months and when I took it out, there wasn’t much power and full throttle didn’t have much pick up. Changed out a rusty tank, went through the carb and now it starts barely with full throttle, runs for a few seconds and dies. Carb is full of fuel. Changed the distributo, rotar, plugs and wires. Now effect. Tried another known good edlebrock 1406 carb and no change.

Any thoughts?

 

[Goldie Driver]

Fuel filter ? Blow thru the lines when you changed the tank ? Bum fuel pump ?

Just throwing some guesses out there.

And, Welcome aboard !

 

[Rusty Nail]

what color is it?

 

[stewy4344]

I did blow through the lines and put on a new filter. Bowls seem to be full of gas and in fact it spits a little gas out of the top when it is turning over.

Color originally was silver and black. Now red, but am going to take it back to silver

 

[Rusty Nail]

That'll be good...I dont like red trucks either.

 

[Paladin]

Get a HOLLEY!!!!

 

[Big Chip]

Is your exhaust plugged by any chance? Bad catalytic converter?

 

[stewy4344]

I can feel exhaust when it is running, but good question on whether maybe the converters aren't fully working. I will try that. I can't think of anything else unless it is a vacuum leak and I haven't been able to find one. Thank you

 

[stewy4344]

I disconnected the exhaust and it did start and run rough with no pick up when applying throttle (although can hear the four barrel kick in). It sounds like number 6 valve was making a clacking sound. Bad valve or cam?

 

[WFO]

I disconnected the exhaust and it did start and run rough with no pick up when applying throttle (although can hear the four barrel kick in). It sounds like number 6 valve was making a clacking sound. Bad valve or cam?

Maybe a rocker arm or lifter.

 

[Bextreme04]

Run a compression test. Then pull the valve covers and do a valve adjustment.

Did you check float level when you rebuilt the carb? Did you do the adjustments to set timing, idle mixture, high idle RPM and idle rpm?

 

[squarelyfe]

Could be a bad fuel pump yet you say it's spitting gas so it's likely not the pump. One test if you don't have a fuel pressure gauge would be to remove it from the carburetor and get a large glass jar to catch it in, see if it pumps steady. If gas shooting out either has too much pressure or 180* out on timing. Still, you say when you peg it it doesn't do much but does it die after flooring it? How does it sound when it idles? Wiped out cam? A video of the starting/running sequence would definitely help

 

[fast 99]

Fuel spitting back? intake valve too tight, bad, or broken spring? Check the vacuum if not steady likely a valve train problem.

 

[78C10BigTen]

Get a HOLLEY!!!!

SMDH!

 

[WP29P4A]

Have a 1979 GMC 1500 with a 350. It sat for 18 months and when I took it out, there wasn’t much power and full throttle didn’t have much pick up. Changed out a rusty tank, went through the carb and now it starts barely with full throttle, runs for a few seconds and dies. Carb is full of fuel. Changed the distributo, rotar, plugs and wires. Now effect. Tried another known good edlebrock 1406 carb and no change.

Any thoughts?

How did it start/idle/run before it sat for 18 months? Was it stored indoors or outside?