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Suggested carb size for a 426 hemi

Started by Meyer, September 09, 2020, 01:22:22 PM

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Meyer

Street driven
4 speed cuda 3:55 rear gear
Close to 600 lift solid roller
10:4-1 comp
Max rpm 6200

Holley says single 670cfm is that anough?

Oldschool

No, not enough for that engine. What intake manifold? I would suggest something like a Holley 950 HP for that car. It will use every bit of that - and then some.

JS29

It has been said CID of the engine X 2=carb size.  :alan2cents:


Cudino

Mopar Performance recommended 850cfm Holley Double Pumpers on their 472" and 528" crate motors, and 750cfm on their 426" crates.  Their 528" had 10.25:1 compression, dual-plane M1 intake, hydraulic lifters with .524/.543" lift.

- Wade

RUNCHARGER

Single plane iintake or dual plane? Stock 426 Hemis ran dual 650's and didn't bog. I think those 950's flow less than an 850. I'd be tempted to run a 1050 Dominator for a single 4 application. I have run Hemis for decades and not once did I think "dang I wish I had smaller carbs".
Sheldon

Chryco Psycho

Hemis move a lot of air , I would use a 950 CFM Proform as the smallest carb choice
1050 Dominator is an awesome carb & I woule thinking about that for sure .

GCragtop

950 cfm if single 4 bbl. 2x600 cfm if dual carbs.


RUNCHARGER

Again, what intake are you running? If it's the MP dual plane it might be best to put it up for sale before investing in a carb for it.
Sheldon

Oldschool

Quote from: RUNCHARGER on September 10, 2020, 06:57:19 AM
Again, what intake are you running? If it's the MP dual plane it might be best to put it up for sale before investing in a carb for it.

I wonder if hood clearance is an issue? :thinking:

Meyer

The stock aluminium dualplane it came with from mopar performance... it has a 4150 street hp 850 dp on it ...

It has a issue ! when cruising its 13.7 afr when accelerating alittle hard it leans it out ,unless i floor it and it overcomes the lean spot and the sec kicks in...

The acc pump cam / nozzles has been switched back and forth but nothing is changed...

Has a 5,5 power valve in it

Brads70

Simple thing but is the pump arm adjusted ok?  :notsure:


Meyer

Yes its not a off idle stumble... wich a miss adjusted pump does

Meyer


Chryco Psycho

So what is the intake vacuum idling , in gear if Auto , the power valve should be at least 1.5 " below that reading , What about the secondary accel pump what size pump shooter & cam . as the secondaries are quickly opened it can go lean if there is not enough pump shot , you might need a 50 cc pump / if you are near .040 shooter you might need a hollow screw , I would want a pump cam that delivers a lot of fuel fast not a long duration shot , do you have enough jet size in the rear so when the pump shot is done you still have adequate fuel through the boosters ?

Meyer

30cc acc pumps
31 nozzles
orange pump cams in no 2 position
9hg at idle
7 power valve
78 front jet
88 rear jets

13.1 wot afr
13.8 cruise afr