Last Place

This is the question I have pondered for months now. People that I have asked are split on the decision, so I'm lost. I have even called the Demon tech line, and got two different answers.

I want to install a Speed Demon 650 on the vette, as soon as I get the engine finished, hopefully before winter. Roughly, the engine will make 350hp. The car is auto, with 3.70 gears, dynomax headers, Crane powermax cam(216/228@ .050, 112, .454/.480) 9.0 compression, 2200rpm stall convertor, AFR 180s, and performer rpm intake.

I know that the rule of thumb is auto=vacuum secondaries. But some folks say a low gear ratio can be the exception to the rule. Also keep in mind that I plan on swapping to a 2004R auto, which will result in an even lower final gear ratio in first.

Also, if I were to go with mechanical, can a choke be added?

What to do? :confused: :crazy: :lol:

GDaina

Vacuum...your cam should pull at least 15-16" of vacuum.

Ryan77

In your case I would go with vacuum, just check to make sure the secondaries are opening fully at full throttle, if not go to a lighter spring. I'm using a Speed Demon 750 mechanical, but I'm running a 525hp 383ci with a 4 speed, so it's a completely different setup :cheers:

norvalwilhelm

I am a fan of mechanical secondaries. At least I know the secondaries are openning and with your gearing jabbing the throttle open at low rpms shouldn't be a problem.
I always use mechanical secondaries and run a pair of 850' s on my bigblock and still get 15 mpg around town.

Last Place

Do you find mechanicals harder to tune?