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for all you old hot-rodders who may have a 4 bbl laying around.....


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i have always suspected that a properly jetted 390 cfm holley would work well

did you mess with the secondary springs at all ??

I had a 390CFM on my 510, mounted to a nice dual-plane manifold. It lasted about 4-5 years before the engine vibrated it to pieces. (A primary Aux-Venturi rattled completely out of it!) That, and it ate the reverse power valves that Holey fits to the 390s.

 

While it lasted it was pretty nice. Good response, good economy, good power, and a REALLY nice sound when the vac secondaries opened! Much nicer than the dual Weber 40DCOEs.

 

What is the CFM rating on that Holley? Is it a 390, or a 500/650 CFM?

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When I talked to McBrat at the show he said it was a 600cfm with off the shelf jetting and he had to tweek with the idle. The engine also has a Delta cam and EA71 pistons too. Then again I may have been just hearing things.

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Craig, that's right.

 

it is a 600 CFM and I had to adjust the idle speed (controlled by the secondary throttle plate).

 

it's a Holley 4160, so it just has a plate for the secondaries,so no jets you can swap out. Secondaries are vacuum operated, and it's got a manual choke.

 

I was flogging it pretty good in the gravel pit at WCSS7.

 

with a considerably heavier than stock Brat and 27" tires, it pulls like it was on stock tires (pulls better I think)

 

In sept. I'll be hitting some hill climbs that will really show me the benefit of the cam....

 

I have to drive it a little differently than my other soobs, that's for sure... can't stomp it down right off idle. gotta be a little lighter with the foot right at first, but otherwise, it runs great...

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