Help identifying QFT carb please

[AC Ventura]

Can anybody help identifying this Quick Fuel carb, which may be a 780 with the auto choke converted to manual. No ID numbers that I can easily see. Fuel feed centres are 9 3/8” and ports 7/8” -20. Also I think the pipe arrowed is called a timed spark port. I guess that’s a little vaccum timing aid. I don’t seem to be using that with my MSD dizzy, so am I supposed to blank it off ?

[AC Ventura]

Also, not sure about the fuel log applied. It’s -6 AN with 7.4mm bore (just under 5/16) on the feed end. Summit says that’s good for a 530 hp FE , but can anybody else suppport that view?

[hauss]

Not sure I to have a QF. carb and people tell me to look for numbers in various places. Still no luck .I have rejeted the carb took it off saw some numbers on the casting but nothing helpful .Let me know what you find out mine looks alot like yours with more polish

[t walgamuth]

You could block off the thing that looks like a vac attachment with your finger to test it. It looks like something which if not being used should be blocked off.....but I have no actual experience with that carb.

Good luck!

[hauss]

Originally Posted by t walgamuth

You could block off the thing that looks like a vac attachment. It looks like something which if not being used should be blocked off.....but I have no actual experience with that carb.

Good luck!

yes mine is caped

[spdbrake]

Yes thats a Vac for the dizzy (if you using vac advance)

https://documents.holley.com/hr_slay...ons_rev._1.pdf

[Gaz64]

Certainly looks like a 780, considering the larger secondary venturi.

https://www.holley.com/products/fuel...arts/HR-780-VS

Did you buy that carb new or 2nd hand? And how old is it?

Looks like yours has been replated when it was converted to manual choke, because I can't find another QFT in that colour.

That vac port needs to capped if not in use, it will be a vacuum leak at part throttle.

Gary

[PeteF]

There are also one or two vacuum ports in the carb base under the front bowl, not visible in your pictures. They provide full manifold vacuum when used. Make sure they are also capped if not used. I don't see a vacuum hose coming from that location, so I assume you are not using those ports.

[Frank Messina]

That is a timed vacuum port that is not needed in your case since you are not running vacuum advance and should be capped off. It does nothing at idle but supplies vacuum when the throttle is opened or creates a vacuum leak if left uncapped. It was a bad idea attempt at emission control back in the '70s and should never be used.

Frank