I'm in the midst of rebuilding a 12-bolt to drop under my '70 Skylark and was contemplating converter stall options and rear gear selection. The car will see mostly street use with limited track use. It must be able to cruise the highway at 70mph. The cam is a Steve Long Grind of the C107A (.499 lift version), and I was thinking of a 3000 stall with 3.42 rear gears. Should I go higher on the stall or higher or lower with the gearset?
How about we first get info as to how many cid your motor is and what compression it has, thanks in advance!
Go gear-vendors or OD trans. https://www.gearvendors.com/hrgm3s.html or http://extremeautomatics.com/ (example)
The 455 isn't completed, and I really don't have an idea what it's going to have for compression. . . yet. The theme of the build is old school. Older Sealed Power Speed Pro 2362P pistons (.030" over with notches), Holley 850 on top of a B4B, Stage 1 iron heads, the "Window Rattler", some flavor of roller rockers, and exhaust flowing through MT Super Scavengers. TH400 of course. I know this combo doesn't scream "streetable", but it's what I have to work with. I sorta figured 3.42 gears are going to be the max I can use to try and keep the RPM down on the highway. I'm just not sure of the rear gear and stall combo, and if It can work? I understand there are a lot of other options available on the market as far as camshafts and overdrives go, but that's not the route I want to take.
So power range of that cam is 3300-6000. You need a minimum of 3500 converter. Get a 9.5" from Jim Weise.
That's where I was planning on getting a converter. Not sure if the 3.42 gear would be a great match, but I think it's the route I'm going to take. Any other suggestions?
3.42 gears will be fine IMO. One of the factors taken in to account when figuring stall is rear gears. A lower numerical gearing will make any converter stall higher. So will a higher car weight, and higher engine torque. Be as accurate as you can with Jim about engine torque, car weight, and gearing, and he will send you the right converter.
If you are more concerned with cruising,and can give up some performance at the strip,get a converter in the 2800-3200 range. We have all acknowledged that this is NOT a matched set of parts,but just trying to make the best of it. Run a good trans cooler.
I appreciate the advice guys. So it looks like gears will be 3.42 or 3.55. Then have a converter built to match the rest, including tire size. I think I should be able to squeeze 28" tires under it. I did have a pair of used slicks (28x11.5) on a set of 15x10 Cragars mounted up at one time and they did fit, but tight.
If yourgoing to run slicks when at the track id say stay shorter to give you more gear there if staying mid 3s.......and for the street I would give up some width and go for height to keep the rpms down. With those gears I wouldn't think you would want much over 3000 flash.......but once you figure out your tire and gear the converter guy will do the rest.
They 15x9s iirc,...but 15x10 with 5.5 Is the most that will go with out messing with the frame,..with a 29.5 on a 10 you'll have to tap the frame in a bout a 1/4in in 2 spots
