Hi, would anyone know approximately what kind of jets do i need to use on a 12BP with Holley 600? As far as i know i already have 65's on all four. I've had the engine reved to like 7k and didn't feel it surging but i want to make sure i'm not running lean before i go higher. Thanks for any help

 

Hmm, I got a 750 double pumper that was on a Racing Beat manifold. It needs a rebuild. I wonder if it's too large for a bridgeport 12A? The RB manifold was for a 12A with slightly hogged out runners directly under the carb, so I guess so. Weird.

How do you check jet sizes? Is there a number stamped on them? It would be interesting to find out what this carb is compared to yours.

 

Yeah, i think 750 is a little bit too big. The speedshop i go to, they use 600 on a 13b peripheral port.
But yeah, the numbers should be stamped on the jets.

 

Oh, ok. Also, this carb has an OMP rod hookup at the end of the throttle shaft opposite of where the cable goes, and has two oil nipples, one on each bowl (obviously because it's a double pumper). I think this is enough evidence for me to say it's a modded carb. I'm just hoping RB did the work. If it's a hack-job, I guess I'll find out when I start closely inspecting it. Perhaps it's a 650? Did RB sell double pumers in 650CFM? I'll go check their website right now.

 

yeah my rb 465 has the same omp rod and bowl trickery. you could check the number on the holley and get the info from it that way, thats what i did to see what parts would bolt onto mine.

http://www.holley.com/HiOctn/ProdLine/CarbList.pdf

 

Gamble, you still don't know what jets you are running, admit it! Yank the float bowl and check!


FWIW, to the original poster - what carb are you going to be running? I am assuming it is a DP, since most "standard" Holley 600 cfm carbs are the good ol #1850, which comes with a non-jettable metering plate for the secondaries. I believe most of the metering plates are about equal to a 72 jet, but it's been awhile since I've played with them. You can always get a kit to convert the secondaries to be adjustable, though. Probably 30-35 bucks at Summit or Jegs.

 

I saw on RB's website that their 650 double pumpers were for 13B bridgeports and have some port matching of the carb barrels to the manifold. I don't recall if they did that for the 12A 600CFM carb manifold though. Heh, well whatever engine size that RB manifold was for, it did have port matched runners directly below the carb. You know, I never did measure that manifold; it could have been for a 13B afterall.