Posted by Gary in CO [64.234.252.216] on Friday, December 27, 2013 at 05:52:02 :
In Reply to: Re: 318 poly Intake manifold posted by Kaegi [98.247.164.246] on Thursday, December 26, 2013 at 22:04:30 :
I don't have a stock 4bbl. The Eddy, Carter and Holley are probably much better carbs. After much tuning I got 20mpg with the 500cfm Carter and the Weiand on a flat milage conscience run of 50-55mph. Not bad for 5K of metal and 4.10s. I don't know what the cfm is on the primary venturis, but is most likely far less than a stock 2bbl. The stock manifold was acting like a restricter plate and someone had the primary and secondary jets switched, so it was not running right. The photo shows the stock manifold with the Carter 500 spacer plate. You can see the restriction, as much as 30%. It might have even kept the butterflies from opening all the way. You would need to machine out the holes or completely open up the plenum.
Holley makes a 390cfm for V6 Buicks and Slant 6 and such.
G
Follow Ups: