Holley, different carb sizes / same parts?

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360duster

360duster

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Hi guys, i´m wondering about the cfm rating of Holley carbs. You can buy main bodies and throttle plates from a lot of manufacturers, they say these parts can be used from 650 - 800 cfm DP´s, for example. I do have a 650 DP (list no. 80777) and wonder what causes the differences in air flow capability to the bigger ones if it´s not the main body or the throttle plate?

Maybe some experienced guys can give me some info, Thanks!

Michael
 
360duster said:
Hi guys, i´m wondering about the cfm rating of Holley carbs. You can buy main bodies and throttle plates from a lot of manufacturers, they say these parts can be used from 650 - 800 cfm DP´s, for example. I do have a 650 DP (list no. 80777) and wonder what causes the differences in air flow capability to the bigger ones if it´s not the main body or the throttle plate?

Maybe some experienced guys can give me some info, Thanks!

Michael
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Its in the mainbody & throttle plates, If you get a decent holley book you'll learn alot i'll tell ya, the base plates on the DPs are the same size from the 650-800 carbs, the difference is in the mainbodies/boosters sizeing.
 
JoeDust451 said:
Its in the mainbody & throttle plates, If you get a decent holley book you'll learn alot i'll tell ya, the base plates on the DPs are the same size from the 650-800 carbs, the difference is in the mainbodies/boosters sizeing.
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Throttle bores differ, as well, and so do the booster venturi's
 
JoeDust451 said:
Thats what i meant when i said "mainbody", that should cover it all sir isaac newton. :-D
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I don't think we need any sarcasm? I understand you to say up above that "the base plates on the DPs are the same size from the 650-800 carbs" but that is where the throttles are

Just try'nna be correct. It's been awhile since I've had a stack of 650-850 dp's in front of me, and that HAS happened, a long time ago.
 
Throttle plates in the baseplate are the same size from 650-800 carbs... 1 11/16"
850's are 1 3/4"

Of course the bores in the main bodies differ slightly in taper, etc. on those size carbs from 1 1/4 to 1 7/16 venturi size.
 
67Dart273 said:
I don't think we need any sarcasm? I understand you to say up above that "the base plates on the DPs are the same size from the 650-800 carbs" but that is where the throttles are

Just try'nna be correct. It's been awhile since I've had a stack of 650-850 dp's in front of me, and that HAS happened, a long time ago.
Click to expand...

I'm just jackin with ya :-D
 
Thank you guys for the info, got it now. I thought the main bodies are the same from 650 - 800 cfm, but this is not the case. 650 cfm carb has got smaller venturi size and that´s why there´s a difference in airflow.

greetings from Germany

Michael
 
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