I'm in the process of having a Pro Street 70 Camaro put together: 90% of it's use is around town and the remaining: once a year to Hot August Nights Reno,Nevada (240 miles round trip) and occasional run at the drag strip. The builder states the BB Chev 496 will easily make 600 HP gross and over the 500 foot pounds of torque. It will be hooked up to a racing 400 turbo trans and a 9" Ford with 35 spline axles.


The builder wants to go with a 4.30 gear set but friends of mine who have built cars and their associates state that 3.90's would be a better set-up more for a little better gas mileage. I already have accepted the pathetic miles it will obtain and the reduced rpm with the 3.90's really does not amount to that much.


Your thoughts.


Thank you

 

The increase of decrease in RPM is about 200 rpms for each gear selection. With the jump from 4.30 to a 3.90 would reduce the rpms ABOUT 400 rpms.

 

What diameter rear tire will be under the rear? A 600 hp BBC wont much care about gear ratio, as it will be pathetic mileage regardless. I'm running 3.73 with a 30" tall slick, and probably 100 hp less, and I average about 5-6 mpg. I'd rather have 3.73 gears if you were doing a little more highway driving, but considering your car will be at 35 mph or less, either gear ratio will be fine.
My biggest concern would be having a fuel truck to follow me the 120 miles to Reno! Hope your tank is large enough to make it from gas station to gas station out on the highway!

 

The 240 miles to Reno may not seem like much but with even the 3.90 gears you'll be rattled when you get there. Also, if this is a Carb engine, you'll wish you had trailered it to Reno. How do I know, I had a 64 Malibu with a built 283 (this was a very strong sbc), and when driving to Reno from Sac, got up on the hill and got passed by a VW. The air was just to thin over the pass and motor didn't want to run.( A stock motor would have done better).

 

Shalamara,s 7/26 post on altitude drivability brings up a point that I overlooked. I have been thinking about an EFI setup for possibly later and the EZ-EFI by FAST has really sparked my interest. I really need to post this elsewhere on the forum for EFI recommendations.


Thanks

 

not that hard to change a 9 inch center section. get both 370 and 430 center sections. switch to the 430s when at the track. takes about an hour. may want to go 340s.

 

Yes, if money isn't an issue, then I agree with having two pumpkins to swap. Since you already mentioned not doing much freeway driving, I also agree that a low rear gear, and trailering to anything farther than 50 miles would be a consideration also, even if altitude isn't a concern.

 

Just a little fyi, a second pumpkin costs a little bit less than a car trailer and a truck to pull it with!

 

12-14 hundred

 

Yeah less than a truck and trailer, but considering how rarely it might get used, I'd rent a truck and trailer, and still be money ahead, and save the labor of swapping.