Carb sizes...need advice.

gandalfthegrayMember

Looking to replace the tired carb on my engine. I have identified the engine so far as a 373 windsor with C-302 SVO heads. I am thinking of the Barry Grant Demon carb. Question is which size. I believe I need the 750. However, I may be pushing the engine up to a 427 in the future and I don't know if that would be enough carb at that point. I noticed that the "Hammer 427" that PI sells comes new with an 850 Demon. This leads me to believe that I would then need the larger carb later if I rebuild the engine. I think. And can the 850 be tuned down enough to run on the smaller engine?

Than there is the concern that if I buy the 750 to start with, then change to the 850 later, will I have to perform an excorcism to remove the Demon from the engine?

Steve

8/25/0510:27 PM

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huskerMember

Give them a call. I'd look on their website first as they have a list of information they will request from you; cam specs, engine, vehicle weight, etc. They will gladly give you a recommendation over the phone.

8/26/057:18 AM

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George PAdmin.

Steve keep in mind, Demon carbs are "wet flowed" so their flow numbers don't agree with Holley's flow numbers. There's a difference of about 100 cfm. A 750 Holley is the same size as a 650 Demon, etc.

The other thing to keep in mind about carbs is the battle between low rpm response & high rpm power. Drag racers run much bigger carbs than what a sports car owner should run. A carb that lowers the intake manifold vacuum at wide open throttle and therefore makes more high rpm bhp, will have worse throttle response at lower rpm, where you will spend most of your time operating the motor. My advice, your current motor will be very happy with a 750 Holley / 650 Demon carb. My experience is that the average bhp across your engines power band, plus throttle response, are more important than a high "peak" bhp number.

Your friend on the PIBB, George

8/26/0511:42 AM

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