Mike,

I have a '69 Dart with a 446-inch wedge, home-ported heads, an 830 Holley, 4:10 gears and 3000 rpm converter. I race (not enough) at 5200-ft and 5800-ft altitude. The car runs 12.40's with 1.78 60-ft times. I know it's still rich (more tuning). The cam is a Hughes solid (.575/.587 lift, 252/257 duration at .050 lift).

I was thinking of a more aggressive converter, say 4000-4500, and perhaps more gear (4:30). The car weighs 3550 lbs with driver, but may lose 100-150 lbs before racing starts here in the high country.

What are your thoughts? Can this package be a wheels-up, quicker set up? Am I heading in the right direction? It's a part-time streeter now, but I am caring less and less about that.

Thanks a lot.

Allen

Colorado Springs, CO

ANSWER:

Yes! You're absolutely right. It's tough to run at a high altitude. You always hear about those hot shot guys running big numbers at sea level, but let's bring them up to the high country and see what they've got!

Our local track is at 2650 feet, but on a warm day it can be 5000-6000 ft corrected air ­ pretty thin air for racing! We have to tune up our cars with more gear, more converter and, just as important, more compression.

Back to your setup: a lot of the 440 style engines need to run some rpm to make good power and you really need some gear with your 3500 lb. car! Depending on tire size, a 4:56 or 4:88 gear is in line, but a 4000 stall would also be in the ballpark. With the big carb, ported heads and that big cam, you need compression to make best use of the thin air. Get that 446 cid air pump working as good as possible with max compression.

Mike

Mike Stewart is owner of Mike’s Transmission in Lancaster, California. He will answer your questions about automatic or powerglide transmissions. Email: Mike@racingnetsource.com

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