I have this Holley square bore with vacuum secondaries and I am considering using it on my L78 396 replica engine. The choke tower has been milled off so I am hoping for your help to determine size of the carb. It has the same size throttle blades (172) as my 3310 Holley 750 but bigger throttle body, about 1,43" across. It´s in good shape, but will need new gaskets. I am not shure if I should bother fixing this carb or just go with my 3310 750?
Yep, 3310's and 1850's, had a few of both. Found this for you, I know it is from a Ford site, may still be useful. http://1970mgr.org/_HolleyCarbs.htm
the metering block numbers for all the factory BBC 780 carbs I looked up in the Parts and specs manual are MIA. With the choke horn gone, I don't think you are going to be able to get any closer than what I pm'ed you. There are a lot of different list #'s for the factory BBC carbs. If you are using the factory high-rise square port intake, it should work well for you once you get it dialed in.
You second photo shows little rectangular "warts" on the venture boosters. The OEM factory engineers specs carb intended for specific engine to have these little warts, to tweek the air flow to richen, or lean, individual cylinders. Mostly done for engines using GM, dual plane intake manifolds, like the 427", 425 HP, or the L88 and ZL1 big blocks. I am not a Ford person, so I can't tell you if Ford did the same, and it does appear, as another responder noted, that your carb has a Ford style automatic transmission linkage lever on its driver's side. I used to have the red Holley "parts and specs" catalog, which could have been referenced using any still visible numbers. It may be that you have a real GM hi-po carb equipped with a replacement throttle plate because the PO broke a mounting ear off the original base plate.
Interesting, thanks Turnaround. The numbers on the metering blocks are 8392/47771 primary and 6497/47771 secondary.
An early 780 (3310) with secondary metering block for jets, before they changed them to 750 and went to a secondary metering plate. That is definitely a Ford kick down linkage, too. But like Turnaround said, people break the ears off the base plates all the time so that could easily have been swapped.
The metering blocks are from 650 double pump carb.. ( 4777...) Looks like it's built up from spare parts..the secondary bowl has accelerator pump... Universal 3310 780 cfm from back in the 80's had ford kick down on it... 2 most popular and cheapest holleys sold for decades... 1850....3310.... Facts from the old tired ( retired ) Parts guy..
Ok, thanks. What would be the correct size base plate for a 780? I assume it would not be a problem buying a new one from Holley?
Now that Dave points it out, I can't believe I missed that secondary pump. Hakno, you have a bunch of mixed up parts there. Double pumper bowls and metering plates on a vacuum secondary body and base plate. It is going to take more than a different base to make all of that work together. Those metering blocks won't work with that body, even though it bolts together. You would be better off trading it to someone for parts and getting a different carb that hasn't been stitched together like Frankenstein.
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