So I bought what I was told and believed to be a QuickFuel 750cfm double pumper with no choke and Holley bowls. I took it off of my truck because once the engine got warm and I shut it off, then if it was 15-30 minutes later I would try to start it up and it would begin to crank and then continue cranking for at least 5-6 seconds before hesistantly starting and then it would blow out black smoke through the exhaust (Still Has me puzzled as to why it does that.) but I took the carb off of my truck, and looked for a list number and after looking for awhile could not find one, I took the bowls off and looked at the primary and secondary jets and the jets were both smaller numberically than QFT list for the 750 Cfm double pumper which is 74 for the primary and 84 for the secondary jets. So then I took the metering blocks off to look for a number stamped on the main block and after removing the primary metering block side it read QFT Patented, but on the secondary metering block side it read Proform 600. I flipped the carburetor over and measured the throttle bore size and it measured 1-9/16". I'm a little confused as to what carburetor I have and the issues I'm having. If anyone has any idea please help

 

Good starting under all conditions is very dependent on proper install setup, float levels, accelerator pump shot, idle mixture etc. The jets won't factor on startup. Did you install it from new, sounds like it was a used carburetor?

 

I bought the carburetor used from a guy that said he bought it new and said it was a 750

-I also believe that if I could figure out what carburetor it is I could change all the jets back to factory size, and everything that's been changed back to factory specs and start tuning it from there.

 

Here's the carb

 

I'd call them, I bet they have a tech line. Summit or Jegs or somebody like that probably has the manual for download too.