[462ta]

presently have 72 formula with 406, ported 13's crower 60916-221/229cam, auto with 3.23 gears and 28in tires, am i right to believe that going to 3.73 gears will provide a noticable diff in performance, i don't drive much over 50 - 60 mph when on the hwy so revs are not critical. Did read the archives and some experiences were shared.thks

[ericwy]

I recently swapped from 3.08 open to 3.42 posi, which is about 11% increase in gearing. I did notice a nice increase in acceleration. When I swapped my th350 for a th700R4 with its deeper 3.06 1st gear it provided about 21% increase in gearing. That was like "holy crap" increase in acceleration.

Your 3.23 to 3.73 change nets about 15% increase in gearing so I am guessing it would fall in between nice and "holy crap". Definitely noticeable IMO.

[67drake]

Similar set up in my GTO,a 406 w/Crower 60242 (similar to your 60916).
I switched from 3.23's to 3.90's this year. It pretty much rendered my street tires useless below 20 MPH. I went from a Goodyear 255/60/15 to a 10.5/27/15 MT ET Street to be able to get any traction. 60' times at the track dropped .3 of a second. Anyway,yes ,it made a nice difference with the gear change as far as acceleration. I too almost never drive on the highway. Any driving above 60 MPH is annoying.

[rad400]

I have driven my 406 with 3:73 #12 heads crower 60210 229/239 @.50 on the hwy and it is a bear and 3500 stall, but only about 6 miles.

[tlwatkinson]

I have 4.11 gears with 275/60/15 tires in my Lemans. At 60 mph the tach shows around 3000 rpm. Plenty of power to the road but that rpm sustained is not good for an engine unless it's in really good condition. If I had known better at the time that I put them in I wouldn't have used them. I think 3:55 gears would work much better. Just my 2 cents.

[grandville455]

If you are just looking for better acceleration, but keep your high gear for cruising why not try a lower first gear set, I ran One in my grandville when it had 3.42's and it was a big difference, think if i remember right it was worth 2 tenths and two mph in the 1/4.

[Old Goat Racer]

Originally Posted by 462ta

presently have 72 formula with 406, ported 13's crower 60916-221/229cam, auto with 3.23 gears and 28in tires, am i right to believe that going to 3.73 gears will provide a noticable diff in performance, i don't drive much over 50 - 60 mph when on the hwy so revs are not critical. Did read the archives and some experiences were shared.thks

If you had an A body rearend, I would swap ya even up.