Carb Recommendation - Chevelle Tech
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post #1 of 33 (permalink) Old Jul 23rd, 19, 2:57 PM Thread Starter
Mark
 
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Carb Recommendation

I've tried the formula and the carb calculators but I get so many varying cfm numbers.

What do you guys recommend for a street car that I like to put my foot in? Here are the details:

Small block 350 bored 30 over and am going to run a flat tappet cam with an rpm range of 2500 to 6500. Compressions is 9.5:1 with headers, high rise, etc. I have an older 600 cfm edelbrock and a holley 870 cfm. I think one is too little and the other is too large. Something in the middle?
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post #2 of 33 (permalink) Old Jul 23rd, 19, 3:09 PM
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Re: Carb Recommendation

750 vacuum secondary Holley.
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post #3 of 33 (permalink) Old Jul 23rd, 19, 3:24 PM
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Re: Carb Recommendation

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Originally Posted by bracketchev1221 View Post
750 vacuum secondary Holley.
Agreed.

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post #4 of 33 (permalink) Old Jul 23rd, 19, 7:44 PM
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Re: Carb Recommendation

or 750 Q-jet

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post #5 of 33 (permalink) Old Jul 23rd, 19, 8:08 PM
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Re: Carb Recommendation

I don't disagree with the above selections but if you already have a 600 and a 870, either of those will work fine also. Unless you are looking for gas mileage or a race carb, there will not be a noticeable difference in a weekend cruiser. I would just use either one that you have and save your money for something else.
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post #6 of 33 (permalink) Old Jul 23rd, 19, 10:26 PM
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Re: Carb Recommendation

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Originally Posted by Tom Mobley View Post
or 750 Q-jet
They work on a 230ci V6 to 500ci Caddy.

Jim

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post #7 of 33 (permalink) Old Jul 24th, 19, 6:50 AM
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Re: Carb Recommendation

well, its true that mathematically 750 cfm fits the bill, esp above 6000. If you had a 650 cfm , it'd be close enough.

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post #8 of 33 (permalink) Old Jul 24th, 19, 10:30 AM Thread Starter
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Re: Carb Recommendation

Thanks everyone. Next question - is it worth going with the double pumper?
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post #9 of 33 (permalink) Old Jul 24th, 19, 10:36 AM
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Re: Carb Recommendation

I recommend a Holley Sniper carburetor

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post #10 of 33 (permalink) Old Jul 24th, 19, 10:57 AM
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Re: Carb Recommendation

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Originally Posted by Vellen06 View Post
Thanks everyone. Next question - is it worth going with the double pumper?
Not on a street car without a strong understanding of how to set one up.

70 Camino...Roller

69 Malibu Stock 307, Reverse Manual TH350, 4,500 Stall Edge Converter, 4.56 Spool 35 Spline 12 Bolt

76 C20 VortecPro 496 628HP 655 lb/ft TH400 Edge Converter, 4.10 14 bolt
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post #11 of 33 (permalink) Old Jul 24th, 19, 11:10 AM
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Re: Carb Recommendation

Quote:
Originally Posted by Vellen06 View Post
Thanks everyone. Next question - is it worth going with the double pumper?
Unless you have a loose converter or a 4 spd. with 370 or higher gears with lousy gas mileage...........Not.

Louis
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post #12 of 33 (permalink) Old Jul 24th, 19, 12:28 PM
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Re: Carb Recommendation

Quote:
Originally Posted by Vellen06 View Post
I've tried the formula and the carb calculators but I get so many varying cfm numbers.

What do you guys recommend for a street car that I like to put my foot in? Here are the details:

Small block 350 bored 30 over and am going to run a flat tappet cam with an rpm range of 2500 to 6500. Compressions is 9.5:1 with headers, high rise, etc. I have an older 600 cfm edelbrock and a holley 870 cfm. I think one is too little and the other is too large. Something in the middle?
If you can get the 600 Eddy right it will be the best carb on that engine. Go with the 1405 specs as the jetting and rods are great. The key to making it work right is getting that sec. air valve to not open to fast then you get a bog off the line. The Holley 870 while it is big you can never over carburetor with a VS model, the stiffer the sec. spring the lees likely you will have trouble with it. As far as DP carbs go I have run them on the street all the time with no problems that happens when you go too big. Get a 4777 650 DP and it would work great also but the Eddy will be better on fuel mileage.
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post #13 of 33 (permalink) Old Jul 24th, 19, 12:52 PM
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Re: Carb Recommendation

Big Cam, small block, 9.5 to 1 compression ---- I recommend a carb. with "idle-eze". I use a Holley 750 Ultra XP body (has idle-eze) with standard double pumper 4150 Holley/Quickfuel throttle plates, bowls, metering blocks in my 402 (bored 30 over). The idle-eze is so important because with a big cam and a nice lean 850 rpm idle, it allows you to pass air to the motor without opening the throttle blades. You can keep the throttle blades closed, metering screws turned out, and as soon as you open the throttle - no lean stumble. It made a huge difference for me with my Comp Cam 292H. PS. You can accomplish the same thing by drilling your throttle blades, but, the idle-eze is much easier to fine tune.
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Harry
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post #14 of 33 (permalink) Old Jul 24th, 19, 1:05 PM
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Re: Carb Recommendation

Quote:
Originally Posted by Vellen06 View Post
Thanks everyone. Next question - is it worth going with the double pumper?
manual trans, maybe, auto trans, likely not. DP are a bit less forgiving than VS carbs, to tune that is. But dont let Louis disuade you, it isnt rocket science in the least. Yet, teh VS carb maybe more plug and play.

Gene
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post #15 of 33 (permalink) Old Jul 24th, 19, 1:22 PM
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Re: Carb Recommendation

Of the carbs you have I would use the Edelbrock. The 870 will work but won't be as responsive with the huge primaries and you'll have trouble getting the idle/transition/mains balanced. Fuel mileage will suffer and it will feel lazy. You might be giving up a little power with the 600, might not, but the response will be better and it will be pretty easy to get set up. If I were in your shoes that's what I would do. I wouldn't buy another carb, I'd save that money for an EFI.
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70 Camino...Roller

69 Malibu Stock 307, Reverse Manual TH350, 4,500 Stall Edge Converter, 4.56 Spool 35 Spline 12 Bolt

76 C20 VortecPro 496 628HP 655 lb/ft TH400 Edge Converter, 4.10 14 bolt
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