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-   -   What size carb should I use? (http://www.hotrodders.com/forum/what-size-carb-should-i-use-2875.html)

HotRodS10 07-07-2002 08:22 PM

What size carb should I use?
 
I have a 350 out of a 85 vette that I'm about to drop in my 87 S10. The motor is stock internally except for the 280H comp cam and double roller timing chain. I'll be running a Holley street dominator intake (single plane) with headers. I'll probably use a Holley double pumper carb but should I go with a 650 or a 750. Is there that much difference between the two? The tranny is a Turbo 350 with the stock converter and the truck will only come out on the weekends. Any help would be appreciated. Thanks, HRS10 :cool:

4 Jaw Chuck 07-07-2002 08:31 PM

My opinion....Holley 750 DP.

1FST2M6 07-09-2002 10:09 AM

the 750 is way to much carb for your application.. a demon 625 or a holley 650 with tiny primary jets would do the trick jsut fine.. you'll have just over 300lbft at the ground.. no need to waste fuel and $ with a bigger carb.


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12.92@109mph out of a 2.8 automatic... whats your excuse?

[ July 09, 2002: Message edited by: 1FST2M6 ]</p>

F-1Rodder 07-09-2002 02:28 PM

Technically speaking it depends on the maximum rpm you will be running. But off the cuff, I would say that a 650 or so would be plenty for your mild motor.

Sandman 07-09-2002 09:23 PM

There is a simple calculation to work out the required cfm. Simply: cubes x max rpm divided by 3456. So we know yours is a 350 ci so say for your max rpm is 6000, 350 x 6000 = 2100000 divided by 3456 = 607 minimum so in this case I would go for the 650 cfm. If you want to build higher revs say 7500, 350 x 7500 = 2625000 divided by 3456 = 760 so you woud just get away with a 750. So as you can see it is all dependant on revs. The same equasion applies even on a blown motor, I have a 400 sbc running a 6-71 blower @ 6500 revs, so 400 x 6500 divided by 3456 = 752, so we run a 750 cfm..

Hope this helps

Cheers
Sandman :cool:

1FST2M6 07-10-2002 10:23 AM

sweet.. wasn't aware of the formula! that'll come in handy! so obvious but obviously i wasn't thinking...

[ July 10, 2002: Message edited by: 1FST2M6 ]</p>


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