Greetings!

I recently purchased a 1978 Ford F150 with a 351 Windsor and C6 transmission. The PO put on an Edelbrock Performer RPM intake, a Performer 650 CFM carb with manual choke, a Performance Distributors Davis Unified Ignition, and a Performance Distributors Adjustable Timing control.

I have to hold my foot on the gas to get it started and hold it there until the engine warms up, otherwise the engine dies. Once it is warm I can open the choke fully and the engine idles roughly. I adjusted the idle mixture and got a maximum vacuum of about 15 inches HG. If I adjust the timing control to 12 degrees advanced, the engine smooths out nicely and I can get almost 20 in HG. However, the truck will diesel for about 10-20 seconds at this setting.

What am I doing wrong? What is the purpose of the adjustable timing control? Any ideas how to fix this?

Thanks in advance for any suggestions.

 

so this must be a 2wd truck then.

how new/old are the spark plugs and what type? how do the plug wires look? is the gas new or old?
Perhaps the carb needs rebuilt. I am not familiar with the dizzy, ignition setup you have. but the adjustable timing control must take the advance out to set base timing. perhaps there is a spout connector or something that needs pulled to allow for this.

 

SOunds like a vacuum leak to me. Spray around potential leaks with carb cleaner. Pinch off vacuum lines with needle nose pliers.

 

The truck is a 4WD. I am not sure how old the spark plugs are, but they say Autolite 25. I pulled the one out of the #1 cylinder and it was covered in carbon. The plug wires all look fine, they are Bosch Ultra-Premium 8mm Opti-Layer Mag Cures.

I removed the timing adjuster per Performance Distributor's recommendations but I couldn't get it started. I quit and unhooked the positive battery terminal when I saw smoke coming out of the air cleaner.

The vacuum lines all looked fine.

Apparently the DUI needs a 12V connection. Right now it is attached to the factory ignition cable so I don't think it is getting the full 12V it needs.

Thanks for the suggestions guys.