Cmwry

Hey guys so I recently converted my 66 from 2bbl to 4bbl and I have a Holley 1850 from the start it had a little hesitation when you first get going. We found the power valve was bad and that took care of the hesitation well so we thought it now will hesitate when you get on the throttle. Something clearly isn't right and I was just curious if someone could shoot me their 2 cents. Thank you.

MustangFTW

How many cfms is that holley, how much horsepower you makin?

mikenkiki05

it may be your squirters are to big and your floats may be set to high we need a tad more info tho

mikenkiki05

if im not mistaken to hold me to it but......

1850 is a 600 cfm carb single feed fuel line

jets from factory are 64 with plates in the back to equal size 66 jets for the rear

and squirters from factory are 31's

if i was u i would run like 22-25 squirters unless its a heavly modded motor

and i would stick a small screw in the secondary lever to open the back butterflys at 1/4 throttle, i use to do this for our 750 holly double pumper when we ran dirt track racing

if you change out the power valve to a 55, put a metering block on the back and square jet the carb and stick a screw like i said you will see a improvement in throttle response jmho

Cmwry

Yes it is a 600 cfm I know that's a little big but it's almost
Like the accelerator pump is screwed up that's how it seems but it's a brand new carb just wanted to trouble shoot before I sum up it's the accelerator pump

67mustang302

What squirter and pump cam is it using, and what engine setup is it on? And has the idle been set right? And does it only hesitate on initial acceleration, but after a few seconds runs fine? Or does it just suck the whole way around when you try to accelerate.

PaulS

In spite of all the advice you are getting to modify that carb it is an excellent carb for the 302 -351 at street level.
I believe the only problem you have is a poor adjustment on the accelerator pump. The pump should push fuel through the shooters as soon as the throttle moves the plate - there should be no clearance at the idle position. at wide open throttle there is a recommended play so the diaphragm is not ruptured.
Just clean up the adjustments and that carb will keep you going for a long time.

mikenkiki05

all hollys i have ever run we ran 34 thousands gap for accel pump and if i recall we ran the orange spring which was a lil softer the yellow cam and spring is what cam factory in the 600 cfm's if i recall right

mikenkiki05

and this is from the holley techs holley recommended settings on all holleys for the rich lean screws is 1 1/2- 1 3/4 turns from fully tight and that came from a holley carb tech person that builds holleys for a living for drag cars that is with the right jets also tho some people i have saw racers run 2 1/2 turns out

67mustang302

Ok starting point, but especially in a modified car you have to give it what it needs. I have to run mine with 0 accel pump clearance, and my idle mix screws only about 3/8 of a turn out(4 corner idle).