[rfmaster]

Originally Posted by Test Pilot

Not to severly deviate the topic, but since all of this good info is here in one thread I thought I'd add this for those of us following along that are in 72 and older trucks.

The below article (see link) has some info on how what the magazine guys did a 5.3 swap in a 68-72 C-10. Specifically what sparked my interest is what they did for the return line. I plan to take it a step further and make a line that attaches to the pipe thread fitting they welded in and dumps at the bottom of the tank and pointed away from the pickup.

I hope this helps someone.
Thanks to the OP and knowledgeable posters for adding thier info. I have yet to start collecting parts, but the TBI Swap is in my top 3 of my short list of things to do this thread will be invaluable when the time comes to start installing parts.


http://www.classictrucks.com/tech/09...all/index.html

Welcome to the board and the TBI swap thread.

Firstly, I would advise you not to weld-in return line bung at the bottom of tank! The reason for this is that a stock TBI system is a relatively low fuel pressure system (stock TBI is content with 13 PSI give or take). TBI uses a spring loaded fuel pressure regulator (FPR) on top of the TB. For FPR to function correctly (i.e. steady 13 PSI) there should be minimum back pressure in the return line. By installing return at the bottom of the gas tank the return fuel must overcome the weight of fuel present in the tank. Soooo with that in mind install return line at the top of the gas tank as shown in the classic trucks article. In addition, I would also add a vapor line from the tank a charcoal canister. IFRC, early trucks did not have charcoal purge canisters, but it makes good sense and it does not cost any performance.

//RF