[junkyardjeff]

I have a 460 Ford that is setup for a spreadbore carb with the normal holley square flange bolt pattern,I know holley made spreadbores but are they the regular bolt pattern or made to replace a quadrajet with the QJ bolt pattern. Jeff

[Jmark]

I know Ford made the square bolt pattern with a spread bore design carb. The also made a Qjet style bolt pattern for some spread bores too. I believe some BBF's came with a Carter QJ carb.

[kleen56]

JMark is correct on the information. I do know they sell an adapter plate that goes between the manifold and carb which allows you to run a standard carb on a spreadbore manifold. That might be a thought? I believe Holley's bolt pattern was the same on the spreadbore as the standard carbs. I use to have the Holley spreadbore carb and I recall the pattern was the same, in fact a friend of mine put the spreadbore carb on his Weiand manifold and it fit, didn't run, but fit!

[junkyardjeff]

I have a square flange holley on it now with a adapter,I want to remove the adapter and put on a carb that will bolt to the intake. I also have a 500 CFM 2 bbl and in a local junkyard is a 429 with a 2 bbl which is the only 2 bbl I seen on a 429/460,no its not a 400 as I used many parts off that motor for the 429 that was in a 70 torino I had years ago. Jeff

[junkyardjeff]

When I got the truck the motor is in a previous owner adapted a quadrajet on it,with the factory spacer and then the adapter it ran like crap. With the Holley I have on it now it runs alot better but it ont idle as smooth as I would like and I would like to eliminate the adapter to see if its the problem,i do know where there is a square flange intake on a mid 80s van or go with the 2 bbl. Jeff

[kleen56]

Your going to have to find a Holley spreadbore throttle plate or carb to match the intake. I know Summit sells new ones and you may find one on one of the bidding sites or craigslist. The primary holes on the spreadbore are smaller and the secondary are huge. I'm confused here? Do you want to put a 2 barrel carb 500 CFM on a 429? I would think that would be way too small for a 429? Or you can always change out manifolds and use the present Holley you have without the adapter plate.

[kleen56]

Jeff, I'd also check for vacuum leaks on or around the adapter plate. Squirt some WD40 around the adapter, if the rpms change or it idles better, you have a vacuum leak and maybe that adapter is not sealing at either the manifold or the baseplate on the carb.

[barnym17]

I had the same deal on a 460 if you can find the stock Motorcraft carb they run decent otherwise swap intakes for a normal square bore carb the adapter plates makes em run like crap.