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>>>CFM=(Max RPM) x (CID) x (VE) / 3456. I've seen that formula as well and while nice in theory, it doesn't relate to real life but it's a starting point. In Craig's case (mine as well since I've had essentially the same engine), at 5500 RPM (realistic[?]) x 396 CID x 80% (if lucky) / 3456 = a 500 cfm carb. Given an additional 15%-20% that still comes to a 600 cfm carb. Before I put the injection on, my engine was 404 cid, a mild COMP cams 268 grind, headers and good ignition. I always had good luck with the Holley 3310-x series right out of the box. A 750 cfm vacuum secondary carb that is very streetable on an Edelbrock Performer 2-O intake. I think I changed primary jets up/down one size for comparison and depending on the time of year the throttle response was a bit crisper going down one size. Since putting the 1000 cfm injection on I'll never go back to a carb again. Having said that, if Craig's car is going to be a nice cruiser with occasional WOT operation, I'd vote the 3310-x series. If it's going to be a "street racer" (that is, a bit more aggressive), then a 700 or 750 double-pumper would be in order. Everyone has their own method to their madness but the Holley 3310-x series is still a pretty good starting point. Never used an Edelbrock carb and many people swear by them so that may be an option as well. Dale > > http://moparjimsgarage.virtualave.net/carbsize.html > > > > "VE" is an engine's volumetric efficiency. I've > recently read that some people consider this formula to > be a bit too conservative and multiply the result by an > additional 15-20% IIRC. > > The formula shown at the above site is from John > Lawlor's "Auto Math Handbook", which should be part of > every gearhead and shadetree mechanic's library. > > Brad > > > Good Morning All, im gonna add to that Question, > > what determins, the right size Carb, to use how do you know if > its to big or > > to small thanks > > KenD 72 HeavyChevyChevelle > > > ----------------------------------------------------- > To Unsubscribe please visit www.chevelles.net/list.html > To start a new topic, send mail to: [EMAIL PROTECTED] > ----------------------------------------------------- To Unsubscribe please visit www.chevelles.net/list.html To start a new topic, send mail to: [EMAIL PROTECTED]
