with all of the above.
Carb CFM rating for BBC
Thread Starter
Instructor
Joined: Nov 2003
Posts: 137
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From: Clifton NJ
Carb CFM rating for BBC
I'm about to dive into fine tuning the carb on my mildly moded 72 454 with a LM-1 Wideband O2 AFM setup. A couple of local sages have opinioned that the Holley Squarebore 600 CFM carb might be too small for the engine. As we discussed it, they focused on how much the throttleplates would need to be opened at idle to flow the air required, and they thought that too much of the transition slots would need to be exposed.
Any thoughts??
BB NJ Ken
Any thoughts??
BB NJ Ken
Burning Brakes
Joined: Feb 2006
Posts: 1,024
Likes: 1
From: AL
600 is too small for max performance, but i'd bet that if you installed it, you would need nothing special done besides the normal tuning for it to work right.
the better size depends on how car is driven and the rest of the combo.
the better size depends on how car is driven and the rest of the combo.
Tech Contributor
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From: At my Bar drinking and wrenching in Lafayette Colorado
It will idle and run just fine, and can be tuned to provide a very nice level of performance. But it is too small for peak power at elevated rpm.
Tech Contributor
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Thread Starter
Instructor
Joined: Nov 2003
Posts: 137
Likes: 5
From: Clifton NJ
Thanks all for the inputs. If I wasn't on the verge of moving, I'd go fuel injection, but now that is at least a year away.
I put the 600 cfm on go real good low speed throttle reponse, the cam is a .500 lift, short duration, bottom end torque bump stick.
I happen to have a 780 cfm Vac secondary carb in stock, but I thought the smaller throttle plates in the 600 cfm would give the best low speed to 5000. My ride, like myself, is built for comfort, not for speed.
Anyway, I'll give the 600 a shot, and see what happens, If I'm not impressed, I'll go with the 780.
Thanks again;
BB NJ Ken
I put the 600 cfm on go real good low speed throttle reponse, the cam is a .500 lift, short duration, bottom end torque bump stick.
I happen to have a 780 cfm Vac secondary carb in stock, but I thought the smaller throttle plates in the 600 cfm would give the best low speed to 5000. My ride, like myself, is built for comfort, not for speed.
Anyway, I'll give the 600 a shot, and see what happens, If I'm not impressed, I'll go with the 780.
Thanks again;
BB NJ Ken
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From: Seville Ohio
Thanks all for the inputs. If I wasn't on the verge of moving, I'd go fuel injection, but now that is at least a year away.
I put the 600 cfm on go real good low speed throttle reponse, the cam is a .500 lift, short duration, bottom end torque bump stick.
I happen to have a 780 cfm Vac secondary carb in stock, but I thought the smaller throttle plates in the 600 cfm would give the best low speed to 5000. My ride, like myself, is built for comfort, not for speed.
Anyway, I'll give the 600 a shot, and see what happens, If I'm not impressed, I'll go with the 780.
Thanks again;
BB NJ Ken
I put the 600 cfm on go real good low speed throttle reponse, the cam is a .500 lift, short duration, bottom end torque bump stick.
I happen to have a 780 cfm Vac secondary carb in stock, but I thought the smaller throttle plates in the 600 cfm would give the best low speed to 5000. My ride, like myself, is built for comfort, not for speed.
Anyway, I'll give the 600 a shot, and see what happens, If I'm not impressed, I'll go with the 780.
Thanks again;
BB NJ Ken
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
GM delivered 427s in '66 with Holley carbs smaller than 600 cfm... No problem.
