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What size carbs for this Hemi set up?

Posted By: Mopar_Mike

What size carbs for this Hemi set up? - 07/22/15 03:46 PM

I am running a 66 426 Hemi, now a 484 stroker, With a .557 lift
Can, JE pistons Manley rods. Using stock heads, stock intake,
Stock valve train but with headers. Car is 67 Coronet with
4-speed and 4.10 gears. Would a pair of 625's be good?
Thank you.
Posted By: AndyF

Re: What size carbs for this Hemi set up? - 07/22/15 06:10 PM

Should work okay. For a street car I'd use a pair of 500 cfm Edelbrock carbs if they'll fit on your intake. But if you have a pair of 625 carbs they should also work.
Posted By: Mopar_Mike

Re: What size carbs for this Hemi set up? - 07/22/15 06:42 PM

Actually Andy that's what I have now. I am going
To run it at the track once in awhile and I am worried
I'll starve the engine at top end.
Posted By: AndyF

Re: What size carbs for this Hemi set up? - 07/22/15 08:33 PM

Easy way to find out is to put a vacuum gauge on it. If you don't have very much vacuum at WOT then the carbs are big enough.

4bbl carbs are rated at 1.5 inches of Hg so that is what you're looking for. If the vacuum at WOT is 1.5 inches or less then your carbs are big enough. If you have more vacuum than that then you need bigger carbs.
Posted By: ScottSmith_Harms

Re: What size carbs for this Hemi set up? - 07/23/15 04:32 AM

What Andy said is fact. That in hand, I have a lot of customers running similar engines using stock 625's (or my Edelbrock 600 based clones's which are basically the same in terms of fuel supply). I can also build the same clones starting with Edelbrock 750's or even 800's, they all look the same on the outside, but 750's & 800's are usually too much carb for a streetable Hemi combo.

Attached picture Clones A.jpg
Posted By: polyspheric

Re: What size carbs for this Hemi set up? - 07/23/15 05:32 PM

I am worried I'll starve the engine at top end

The result of small carbs is generally rich mixture on top end.
Posted By: mickm

Re: What size carbs for this Hemi set up? - 07/23/15 07:36 PM

i have a 540 with stage V heads that flow around 430 at .700, cam is 248@.050 and .610 on intake. i got the whole setup from tim banning at FHO. when i asked him if i should try 750's, he said no way, way too much carb for this setup...
Posted By: Cab_Burge

Re: What size carbs for this Hemi set up? - 07/23/15 08:43 PM

If your going to use the stock progressive carb. linkage your right foot will control the part throttle driving work The carb. size will control the wide open throttle power shruggy I've owned, raced and built a bunch of 426 street Hemis and larger stroker 426 Hemi motors. I've never treid the smaller 500 CFM but the customers I put 750 CFM carbs. on like those shruggyYour choice up
Posted By: MR_P_BODY

Re: What size carbs for this Hemi set up? - 07/23/15 09:42 PM

Originally Posted By Mopar_Mike
Actually Andy that's what I have now. I am going
To run it at the track once in awhile and I am worried
I'll starve the engine at top end.


You wont starve the engine(which I think you really mean
running out of fuel)... the smaller carbs have smaller bores
so that restricts the amount of air... if you have the jetting
correct you will just run out of power at a lower RPM... if its
a daily driver keep the smaller carbs on it... why burn more fuel
wave
Posted By: JohnRR

Re: What size carbs for this Hemi set up? - 07/23/15 09:54 PM

Originally Posted By Mopar_Mike
I am running a 66 426 Hemi, now a 484 stroker, With a .557 lift
Can, JE pistons Manley rods. Using stock heads, stock intake,
Stock valve train but with headers. Car is 67 Coronet with
4-speed and 4.10 gears. Would a pair of 625's be good?
Thank you.


Mike if you have a truly stock hemi intake you can't run anything bigger than a 625 without modifying the intakes primary throttle bores , or putting the carbs on a spacer that will allow the primaries to open.

If you decide want to go to 750's I have a minty never run set of 750's clones for sale ...
Posted By: Mopar_Mike

Re: What size carbs for this Hemi set up? - 07/24/15 12:13 AM

Thanks everyone for your input. I am not quite finished with the build/car so I think I am just going to go with the twin 500's for now and see how the car does. I did check a plug after breaking in the cam and it was not running lean.
Posted By: astjp2

Re: What size carbs for this Hemi set up? - 07/24/15 02:34 AM

I am running a pair of 770 vacuum quick fuel carbs with annular boosters on the primaries and downlegs on the secondary's. Having vacuum carbs allows me to not over carb and supply enough air at any rpm. Tim
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