69GMC - Lack of Secondaries/Low High-End Power

[davepl]

Originally Posted by Grumpy old man

Post a picture of your engine with the air cleaner off so we can see whats going on , A 750 may be too much carb for your truck who picked that ?

Not likely. GM built the 301 Pontiac with a 750cfm carb and you can run a 780 Holley on a 302 just fine. Assuming vacuum secondaries like a Q-Jet or 3310 of course...

Still sounds to me like it's running out of fuel. If this was me I'd stick a fuel pressure gauge on it so I could monitor it from the cab under load and see if it's falling off. Electrical, of course, don't plumb gas to the cab!