Hi all, I have an 850 double pumper 4781c with choke, I was wondering if there is a good aftermarket hp type main body I could swap in for the benefit of adjustable air bleeds/no choke etc,
Thanks in advance!

The Proform's are nice and Summit has em in stock.........

BLP has some nice stuff too.

Looking on summit I found the pro form main body and Holley offers an up main body for that carb,
The Holley come with 82/82 Jets, doesn’t say what air bleeds
The pro form has 76/84 jets and 33 inner and 73 outer bleeds.

Which would be the better starting point?

I use both in budget builds and BLP Billet for the top dog stuff..........In your case I'd go w/the Pro-form as that jetting is more street oriented w/the jet spread and primary p/v..........

Thanks thumper, I’ll go with that, one of these days when I get it back in the car I’ll get some updates on it!

No problem and let me know if I can help in any way...........

I have a brand new 850 QF/Holley main body carb I tested on my Dart that you can have for $850 shipped if interested...........

I’ll ask a few of my buddies for ya... next carb I get will be a dominator,
But I’m sure I’ll have a few questions with this one, always had super rich idle problems but I finally got a wideband so I’ll be able to see how my tuning is working lol

I finally got a jet kit now I need some airbleeds and I’ll be able to really tinker with it

But here’s a first question, would it be benifitial to block off the powervalves?

that pro form 850 body has smaller venturi size than your old 850 holley

I have to check my notes on the venturi sizes on the PF and the Holley I just got and let ya know but I've used em on fairly stout small-blocks and mild big blocks(not my choice)w/good results. The smaller venturi has it's benefits up to a certain point just as the bigger one does but I agree on a Dominator in most applications making 500+ HP big or small-block.............. I don't memorize this stuff cos it hurts my brain..........

I know what ya mean lol, it’s a little more than mild, not a full race piece but should be stout, deffinately not the best carb for the motor but it should run ok

Rather than buy a new body, why not send the one you have to Thumper? It shouldn't cost more money to have him drill and tap the bleeds to accept screw-ins.

What do you think Thumper?

The down side is the heavy zinc main body and the choke horn although I've done several w/good results I prefer the alum. main bodies and of course BILLET is the shiznit..........

Why not upgrade to a Quick Fuel or Pro Form 950 or 1050 main body? the 850 base plate will work with either.

If you do decide to do a main body swap...... And your current 4781 body is clean and unmolested....... I'd be interested in it(for the right price of course )

I like the way this sounds, will they be a bolt on deal or will there need to be some machining?