moving from a 750 Holley to a 670 Holley

[Scatterbrain]

Guys, I"ve always thought the 750 Holley (part no. 3310-6 2718) on my 318 is way too big for the engine. It sits atop a Holley Strip Dominator intake (single plane).  The only information I have on the cam is that its a 360 magnum cam and stock heads.  The engine sounds loud and mean, but its all bark.  There is no neck snapping acceleration like I get in my Firebird.  I do get really, really bad gas mileage even with a 6-speed (around 10-12).  I've got a chance to get a 670 Holley (with electric choke).  With the 670 combined with a dual plane intake, should I see an improvement in gas mileage? performance? 

[Chryco Psycho]

definatly you will see an improvement , I am a fan of big carbs but a 750 on a stock 318 is way off

[moper]

The 670 is the same size carb. Just wet flowed, so it measures less air. (liquid displaces the air in the wet testing). The 750 when wet flowed flows about 670.... You shoud be going with the 570 cfm Avenger. Which is a wet flowed 625 or so.  Dry flow rating carbs are the old school Holleys, (3310,4150, Dominators, and all the emmissions models; Edelbrocks; Carters, Webers, Rochesters, Autolites, and most older or original carbs. Wet flowed units are all custom shop carbs, Demon, and Holley HPs and Avengers.  It's about 13% less air measured when a liquid goes thru it at the same time. So an Avenger 770 is the equivilent of a 4150 series 830, and the Avenger 570 is about the same as a Carter AVS from a '70 340 at 625 CFM. If you can try to compare apples to apples, it gets easier..lol

[tactransman]

The engine sounds loud and mean, but its all bark. 

Sounds like the cam might be a little too big also.

[Scatterbrain]

Sounds like the cam might be a little too big also.

Got no info on the cam other than its a 360 magnum cam.  Don't get me wrong it will still spin the tires, its justs that I'll drive the chally, then the firebird and notice the difference right away.  The 670 is on its way, I still haven't decided on a dual intake for it. 

[ntstlgl1970]

What else can you tell us about your car, you said 6 speed? manual or this an AT with a gear vendor on it? What rear axle ratio etc. the more info we have the more we can help

[Scatterbrain]

Its a Richmond 6-speed manual with 3.55s in the rear.  Looks like that 670 isn't on its way.  I had purchased the 670 from Brian Torretto's post, but he had an unfortunate accident.  So I'm in the market for something else.  Something better suited to my little 318 setup.