A
Anonymous
Guest
I didn't know if this was the place to post this question but here it goes...what is better, a mechanically driven secondary valve or vacuum actuated?
-Chris
-Chris
A
Anonymous
Guest
They are really ment for two different applications that some times merg together, street and race.
But for everyday duty, you can't beet a vacuun secondary carb. It's more flexible and forgiving and will get you better mileage.
Have you looked at the RoadDemon Jr. 525?
A very pretty carb that is a good size by Barry Grant.
John
But for everyday duty, you can't beet a vacuun secondary carb. It's more flexible and forgiving and will get you better mileage.
Have you looked at the RoadDemon Jr. 525?
A very pretty carb that is a good size by Barry Grant.
John
A
Anonymous
Guest
Funny you mentioned Demon carburetors, that's the brand I've been looking in buying. I think I'm leaning more toward the Road Demon 625 rather than the Jr. simply because my cam has a 260 duration and I don't believe the Jr. is recommended for a cam that high. I will need the power out of my 351W project but not that much and I would like to maintain good highway mileage if possible. So I think 625 CFM would be perfect plus my 2.80 rear end.
-Chris
-Chris
8) you might try the 575 road demon carb instead. i think it is a better match for your 351w. also there is more to secondary operation than just vacuum or mechanical, at least on the mechanical side. you have full mechanical secondaries, that either have twin accelerator pumps, commonly called double pumpers, and you have a carb that is race only called a center squirter that uses a single accelerator pump and the pump outlet is literaly in the center of the carb, and directs fuel to all four barrels at once. then you have the avs or air valve secondary. it is a mechanical secondary carb, but there is an air valve that is controlled by air flow through the carb. when enough air weight is applied, the valve starts to open as needed to feed the engine. two carbs that use this system are the rochester Qjet and the carter avs.
8)
When I wqas just a pup it was kinda a unstated guide that if you had a manual trans you used a 4bbl with mechanical secindaries and if you had a auto trans you used vacuum secondaries.
I feel it all comes down to how much you want to tune the carb. You can change spring resistance to determine at how many inches vacuum you want the carb to open and on a manual you can adjust how far you have to push throttle before secondaries open.
On a high performance with a radical cam you might have problems getting a strong vacuum signal so alot of people use the mechanical secondaries.
When I wqas just a pup it was kinda a unstated guide that if you had a manual trans you used a 4bbl with mechanical secindaries and if you had a auto trans you used vacuum secondaries.
I feel it all comes down to how much you want to tune the carb. You can change spring resistance to determine at how many inches vacuum you want the carb to open and on a manual you can adjust how far you have to push throttle before secondaries open.
On a high performance with a radical cam you might have problems getting a strong vacuum signal so alot of people use the mechanical secondaries.
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