750cfm too much?

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goldenmopar

goldenmopar

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Okay so i am in the middle of installing long tube headers on my stock 318. My neighbor gave me a Holley 750cfm dual feed and i'm planning on getting an Edelbrock Air Gap intake. Is 750 too much carb for the teen? I mean, Chrysler put thermoquads on them right?
 
goldenmopar said:
Okay so i am in the middle of installing long tube headers on my stock 318. My neighbor gave me a Holley 750cfm dual feed and i'm planning on getting an Edelbrock Air Gap intake. Is 750 too much carb for the teen? I mean, Chrysler put thermoquads on them right?
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Seems a bit much for a teen especially if it's stock compression and camshaft. I would think a 650 would be just fine. Thermoquads were different. They had small primaries and the secondaries opened when needed and only as much as needed. tmm
 
Yes. It's too much. The Thermoquad is an entirely different type of carburetor.
 
IIRC the old 318 cop motors had Quadrajets and not Thermoquads on them. Similar layout, small primaries and large secondaries. Both had air valve secondaries which meant that they opened only when the right foot wanted it and the engine could accommodate more fuel.

Don't know about the Holley you mentioned. If it uses a vacuum secondary, it may work out. Otherwise, IMHO, you have some good trading material.

FWIW: My Demon runs a teen with a 625 cfm AFB on a Performer. Throttle response is good.

Someone recently posted some cfm ratings of muscle car carbs. They seem to be a lot less than I recall. See below.

http://www.forabodiesonly.com/mopar/showthread.php?t=285033&highlight=cfm+ratings
 
too much but where abouts are you in california? i might have a 600cfm edelbrock for sale or trade
 
Yeah its big alright. But its free! If I get free stuff that I need, I try it. Whats the worst that could happen? You cant get the bog out, and end up buying a smaller carb. No money lost. Maybe an hour or two of your time. In the mean time you get an education on tuning Holleys.If you can get it working; its a win/win, and you get to come back and tell us how you made it work. That would be a triple win!
-On the other hand, If you just want to bolt something on and drive, That big ol 750 wouldnt be a first choice. Something in the 500 to 650 would probably do it.
-And that AG is probably a little on the BIG size as well.
-The snappiest intake/carb I ever had on a stock LC 318 was an oem cast iron small port spread bore manifold and a baby TQ. Dynomite.
- An aluminum small-port dual-plane spreadbore would be my first choice, even if I hadda put a QJ on it.
 
"If it uses a vacuum secondary, it may work out." Yes it does have a vacuum secondary.
 
The air gap is probably too much intake also, that said I think it will work good I would rebuild it and run it, then if you go to a hotter 340/360 you will have the right intake and carb!!
 
goldenmopar, I got a 650 body that may work out for you. I work in LB for Verizon so Im everywhere. If you decide to keep the 750, get an adjustable vacuum secondary spring set. You can put a heavy spring in there and the secondaries will never open completely, keeping the velocity up. I got a 600 vacuum too.
 
pishta said:
If you decide to keep the 750, get an adjustable vacuum secondary spring set. You can put a heavy spring in there and the secondaries will never open completely, keeping the velocity up.
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Alright thanks i'll give that a shot!
 
With vacuum secondaries think of it as "UP TO" 750 CFM. You may lose a little low RPM throttle response compared to a 600, but it will work fine.

By "dual feed" you mean center hung floats, not double pumper. This confuses people sometimes. Looks like a 3310.
 
C130 Chief said:
With vacuum secondaries think of it as "UP TO" 750 CFM. You may lose a little low RPM throttle response compared to a 600, but it will work fine.

By "dual feed" you mean center hung floats, not double pumper. This confuses people sometimes. Looks like a 3310.
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by dual feed he means it has dual inlet's, one feed to each bowl, a single feed has just a single inlet to the front bowl and a small tube that runs front to back to fill the rear bowl. that being said, bolt that thing on and run it, it will work fine
 
I had a air gap and a 750 dbl pumper on my lil 318 with 360 heads (even lower compression) and it hauled ***!! Way better then any 625/650 i ran on it b4....of course i re jetted it and got the right power valve and tuned it to the 318.... But it hauled *** for years!!
 
CurtDawg510 said:
I had a air gap and a 750 dbl pumper on my lil 318 with 360 heads (even lower compression) and it hauled ***!! Way better then any 625/650 i ran on it b4....of course i re jetted it and got the right power valve and tuned it to the 318.... But it hauled *** for years!!
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Rad! Thanks for the info man
 
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