rod051

Anyone out there running 850 dp's on their 351's and if so what size jets and and pump nozzles are you using. I understand this is a high performance application. I just had an 850 given to me and it had 80 secondary and 91 main jets in it and a 46 and a 31 pump nozzles. I know when they are new this model carb had size 80 jets front and back and 31 pump nozzles.

Rod

BLKEBXR8

Used to have 351 plus 30'' wieand accelarator manifold.closed chamber 2v's with 4v valves . crane F246 cam . with standard jetting & pump nozzles in the 850dp . You didn;t metion power valve size had 6.5 in mine.

STROKEXD

A gap of 11 jet sizes between primary and secondaries seems a bit too much to me. If a Holley DP has a power valve in the secondaries then jets should be the same or nearly the same. Obviously yours has had the PV removed in the secondaries.

Also that jetting is pretty huge, I run a modded 750DP on a 378 that has a biggish cam and all i need to use is 76 primaries and 82 secondaries with #36 & #31 shooters. Jetting shouldn't vary much with an 850DP.

So in other words, the way that carb of yours is set-up you would need to have a very very hot 351.

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russxr67

To start off with you would need a very stout 351 to run an 850. around 500 in fact would put you in the ballpark for such a carb.Someone has really messed around with this carb.Are you saying it has bigger jets in the front than the back? 91 in the front???? how big was the squirter ,46?.This would require the use of a hollow type of screw as well and would indicate the motor it was on must have had a large plenum like a tunnel ram.Does it have a reo pump on the front or is it just a conventional 30cc rig?Sure sounds weird.

rod051

It has a 6.5 power valve in the secondary side but has no power valve in the primary side. There is no place for a power valve on the primary side. It has a 30cc pump on the front and a 50 cc pump on the back. The 91 jets are at the back. It doesnt have a hollow screw for that 46 squirter. I also noticed the throttle plates have been drilled as have the air bleeds on the front. I think its been taken aprt and put back together ass about.

xdclevo

I ran a brand new BG 850 dp on my last 351. It had 85 and 93 jets and i ended up using 80 pri and 88 secondries.(they all use 8 jet split). It was still too fat at idle, but ended up running slighlty lean at wide open throttle. From what i understand is the 850's large venturi's lack sufficient airspeed to pull the correct amount air/fuel mixture through the boosters. Still, it did perform quite nice. Iv'e since gone for a 750 bg with 75 and 83.

Primaries are at the front and secondries are the rear.

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10.70 @ 125.00 on the black fun top
408 Cube Cleveland.

rod051

I had the primary and secondary side confused.

MikGan

BLKEBXR8 , that almost the exact same combo im putting together right now, what kind of performance did you end up with, any numbers to talk of? Anything you'd have changed?

Racer

Put the original jets back in and try again from there.

ps
850DP is WAY WAY to big!

BLKEBXR8

No numbers to talk of but plenty of stained undies, I think that say's it all.motor was fitted to a TD Cortina pretty light car also.