74 gmc 350 start dies

[mikes74gmc]

First time blogging so If I posted in the wrong place please let me know. OK driving down freeway 70mph. I get 3 backfires through the carb and it dies towed. I have replaced the dist plugs wire set initial tdc Adjusted valves all look ok springs etc run compression tests #2 and # 4 no compression all the others ok oh rebuilt Edlebrook 650  mix is 1 1/2 out to start fuel ok.

OK here's the problem. Cranks good tries to start I get that, oh it's going to start but then it dies. I am thinking I should readjust loosened valves while I adjust while cranking. Does anybody have any thoughts on what happen on the freeway? Also, anything else you can think of I should do I am going to look up how to do a leak-down test after I do valves if not fixed.

Edited August 20, 2023 by mikes74gmc