any suggestions on my issue????

[rico7769]

Had my 67 for two and half yrs now and enjoyed ripping everything apart and the whole journey. Here's the build info we are working with. 67 gmc with a 350 swapped from a 77 chevy, hei with new dist cap, rotor, hei coil, wires, accell shorty plugs gapped @ .45, holley 650 w/ elec choke, new fuel filter, three wire alt, new fuel lines and mech pump. Essentially everything is new from the ignition sys to the fuel sys, etc.
When I start the truck, push the gas to activate the elec choke plate closed, fires right up and idles to 2000 until I bump it down once its warm. Idles around 900 and then in gear around 700. Drives fine with no resistance for about 5mins and then when she gets warm, she starts stumling and sits down to about 500 and struggles. When I press the throttle it doesn't hesitiate, it doesn't fight, etc. When it fights at a stop in gear, the fuel pressure still sits at 7psi and is clear as can be running through the filter.

Unless its a vacuum issue, I'm stumped. HELP!!!!

Steve

[mrhino]

It sounds like the choke is out of adjustment. when you adjusted the choke did you do it with the engine cold? (not run in a while)

[71 super]

I had a quad on the 68 that acted like that, it had an internal vaccum leak. I put the cheapo holley back on just to drive it. I would check the carb and if you cant have it rebuilt. I would have, but the one i had was the wrong carb and a piece of junk to begin with.

[pat 70/71]

Intake leak? does the idle change after running the motor up to temp? as said internal vacuum leak could be the answer. Maybe change out the carb to a known good one and test. use new base gasket( this alone has beat me in the past). cheers, Pat

[dadsworktruck]

As with all on line questions you have to take all answers with a grain of salt, that said here is my fix for you...adjust your idle screw on the drivers side of the carb, sounds to me as the engine warms up and comes off choke, which has it's own speed adjustment it then depends on the main idle adjustment screw to hold the lever(butterfly) open a bit .check it out see if that will fix you up..

[long67]

Adjust the Air/Fuel mixture screws after the truck is fully warmed up and running like you discribed, make sure the choke is opening all the way also.