E-Bodies.org Cuda Challenger Forum

Technical Shop => Engine, Transmission & Rear End => Topic started by: Meyer on September 09, 2020, 01:22:22 PM

Title: Suggested carb size for a 426 hemi
Post by: Meyer on September 09, 2020, 01:22:22 PM
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?
Title: Re: Suggested carb size for a 426 hemi
Post by: Oldschool on September 09, 2020, 01:55:39 PM
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.
Title: Re: Suggested carb size for a 426 hemi
Post by: JS29 on September 09, 2020, 02:28:40 PM
It has been said CID of the engine X 2=carb size.  :alan2cents:
Title: Re: Suggested carb size for a 426 hemi
Post by: Cudino on September 09, 2020, 02:38:10 PM
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
Title: Re: Suggested carb size for a 426 hemi
Post by: RUNCHARGER on September 09, 2020, 08:00:30 PM
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".
Title: Re: Suggested carb size for a 426 hemi
Post by: Chryco Psycho on September 09, 2020, 10:23:00 PM
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 .
Title: Re: Suggested carb size for a 426 hemi
Post by: GCragtop on September 10, 2020, 02:22:11 AM
950 cfm if single 4 bbl. 2x600 cfm if dual carbs.
Title: Re: Suggested carb size for a 426 hemi
Post by: 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.
Title: Re: Suggested carb size for a 426 hemi
Post by: Oldschool on September 10, 2020, 07:44:03 AM
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:
Title: Re: Suggested carb size for a 426 hemi
Post by: Meyer on September 10, 2020, 10:40:38 AM
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
Title: Re: Suggested carb size for a 426 hemi
Post by: Brads70 on September 10, 2020, 11:09:18 AM
Simple thing but is the pump arm adjusted ok?  :notsure:
Title: Re: Suggested carb size for a 426 hemi
Post by: Meyer on September 10, 2020, 12:35:02 PM
Yes its not a off idle stumble... wich a miss adjusted pump does
Title: Re: Suggested carb size for a 426 hemi
Post by: Meyer on September 15, 2020, 11:38:02 AM
???
Title: Re: Suggested carb size for a 426 hemi
Post by: Chryco Psycho on September 15, 2020, 05:06:23 PM
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 ?
Title: Re: Suggested carb size for a 426 hemi
Post by: Meyer on September 15, 2020, 10:09:51 PM
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