I think that is a myth that mechanical secondaries use more fuel, the fact is it take x amount of fuel to make x amount of hp. I had a 750 on my gto and got 21.5 mpg on the highway, I did have freeway gears in it but I have also run a bunch of quadra toilets and they never did any better on fuel.poboyjo65 wrote:I agree with Roy. I have a street driven 347. it ran good with a 600 edelbrock, but I needed the 600 to put on a 302 so I put a 650 edelbrock on the 347 & does good with it too. to me, it seems like mechanical secondary's would drink more gas on the street. Your going to have to fine tune what ever you use,,,so I would dial in what you have for the street ,,,, maybe get a big one for the track later on.
My 2 cents
Ant