Posted by Fastman (209.179.228.103) on April 10, 2001 at 15:44:57:
In Reply to: Re: carb/intake combo posted by Chris W. on April 10, 2001 at 03:10:49:
: It's just as easy to under-carb a motor too. You have to take into consideration your overall combo as well. Remember what Shelby used on his GT-350's? A Holley 725 Vac. Sec. All he replaced was the stock cast iron intake and exh. manifolds.
: Without the stock manifolds to plug up the engine, the engine responded to the increased airflow.
: Even on a couple of our cars, the larger carbs made more power and got better mileage then the "so-called" correct size smaller carbs did.
:
I think sometimes this is true.I think it works up to a certain extent. I wouldn't use a Holley 850 on my 302, but I would use a 600. I believe a power and mileage increase is due to the airflow rating. If a 600 CFM carb. flows more air than a 500 CFM, you can lean the engine out a bit to create more power. By leaning it out, mileage also increases. Now, if you go too lean, you can damage the engine, but if you go too rich, you also cause problems. A "too rich" condition is more common with smaller carbs on small engines than larger carbs on small engines. This is the exact problem I am currently suffering with on my 302. A 600 cfm gave better mileage and I had a perfect A/F ratio, while my 500 cfm is way too rich and I get horrible mileage. I think the extra air coupled with the correct jet size leaned the engine vrs. the 500 cfm. I am seriously considering installing my Holley back onto the engine because I am getting tired of this tuning problem I am having.