Hey all, I am sure this has been addressed in one thread or another and I have spent copious amounts of time reading some of them trying to get the best answer - only to get close (in my mind). Anyway, looking for input on whether I should go for 3.73 or 3.90 gears on my Skylark. I originally had a TH350 and when swapping from open 2.56 to posi I went with I believe 3.08 (could be 3.23, cannot find paperwork). Now I have a 2004r and I know I can make it perform better than it does now. Engine is 350 .30 over, 10:1 compression, rochester 4bbl, cast iron intake, manifolds. Mild cam. Anyway, I want to have the ability to break the tires off the line relatively easy but also have some gear on the highway. From what I read 3.73 would be the way to go, although 3.90 has also been mentioned. For my application 4.11 seems to be out. So, with that said what's the thought based off my combination? Again, want the ability to leave rubber at the line when I want but also not be whining down the highway at 70mph. Mark
You won't be wound tight with any of those choices. That's the reason you put the 2004r in. I ran 390's with a turbo 350 trans and it was tough to keep up with the newer cars on the x-way. Now, with the 2004r, just let her eat:laugh::laugh: Run a trans cooler too...... If you want to kill your ratio some, you can go with taller tires. You will have fun showing off with a big gear :Brow: You will be shifting much quicker though.:TU:
Leaving rubber is over rated:grin: When you are burning rubber, you are going nowhere. Having said that, you should be able to turn the tires now if everything is right. Have you optimized your timing? Do you have the right torque converter? I'd look there first. You can run some deep gears with a 2004R, the OD is .67. 3.73's become 2.49 Final drive. 3.90's are 2.61. Again, you should be able to burn the tires now if everything is right with your combination. If you change the gears, go with 3.73's. With 26" tires, it will be more like 3.82. 28" tires tames it to 3.55.
Timing is optimized from what I recall and Jimmy's transmission here in Mundelein did the total trans swap (meaning I cannot recall the converter stall). I have 28" tires, forgot to mention. As for the comment of going no where, I do agree and it's not a plan to do it everywhere. It's a nice to have and would like to leverage the power bands better. Mark
You should be able to turn the tires now. Something other than rear gearing is wrong. You can't evaluate something without specifics. When is your mechanical advance all in? If you don't know, say that you don't know. Was the converter an off the shelf unit, or was the converter built for your engine? The converter and timing will make the biggest differences here.
Larry, Understand the need for specifics and will have to go back and get them, as I do not have stall or timing (initial or otherwise). Once I can get the car back out I will check them and report back. Thanks, Mark
OK, good. I think that is where we will find the solution. Knowing what cam you are using will help also.
