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Old 07-23-2025, 10:10 AM   #1
1964FarmFreshC10
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Holley Carb too big?

I just picked up this Holley 4BBL carb to go with the Clifford intake on my 230 inline 6. The guy sold it to me as a 390CFM but looking at the list number 1273-1 it appears to be 435 or 450 CFM.

I'm hoping this won't be too big for a stock 230 just meant for cruising around town and having some fun.

Thoughts?
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Old 07-23-2025, 01:14 PM   #2
theastronaut
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Re: Holley Carb too big?

Summit has a cfm calculator, it's staying a 230 that revs to 4500 max only needs 254 cfm.

A Weber 38/38 would be a better match, and is easier to tune.


https://www.summitracing.com/newsand...cfm-calculator
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Old 07-23-2025, 02:57 PM   #3
geezer#99
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Re: Holley Carb too big?

A good carb to use.
With vac secondary you’ll be just using the primary 90% of the time.

I thought the Clifford intake turned the carb 90 degrees.

Last edited by geezer#99; 07-23-2025 at 03:07 PM.
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Old 07-23-2025, 04:45 PM   #4
1964FarmFreshC10
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Re: Holley Carb too big?

That was my understanding as well but this intake came with an adapter plate when i purchased it and that's the orientation that fits the carb.. The older gentlemen i got it from owned a performance machine shop so maybe he made the adapter. As can see from the below pic he modified the intake to be dual plane.

He said he purchased this intake from the Clifford factory in California in the early 1970s when he drove out there in his hippy van LOL so maybe its an early version?

Quote:
Originally Posted by geezer#99 View Post
A good carb to use.
With vac secondary you’ll be just using the primary 90% of the time.

I thought the Clifford intake turned the carb 90 degrees.
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Last edited by 1964FarmFreshC10; 07-23-2025 at 04:53 PM.
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Old 07-24-2025, 06:17 AM   #5
4u2nv
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Re: Holley Carb too big?

Quote:
Originally Posted by 1964FarmFreshC10 View Post
That was my understanding as well but this intake came with an adapter plate when i purchased it and that's the orientation that fits the carb.. The older gentlemen i got it from owned a performance machine shop so maybe he made the adapter. As can see from the below pic he modified the intake to be dual plane.

He said he purchased this intake from the Clifford factory in California in the early 1970s when he drove out there in his hippy van LOL so maybe its an early version?
That"s a cool piece there ,never seen one before and probably never will again Wish I could hear it run
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Old 07-24-2025, 11:58 AM   #6
SkinnyG
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Re: Holley Carb too big?

You have it, run it.

If you run into tuning problems because you can't get a good vacuum signal, burn that bridge when you get to it.

Rochester Q-Jets were like 780cfm, and were on everything from 500-inch Caddy's to 4.3L V6's. The general go-to for a small block is a 650. You will probably be just fine.
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