Rear and trans combo

Hey guy's I have a 1965 skylark with a 430 and a comp cam 96-202-4 . I had 3:55 gears put in the rear and now my cruising RPMS are a bit too high for my taste. I am looking to take out the ST400 switch pitch and go to an overdrive trans to get some highway driveability. My options are 200 r4 or 700 r4 which do you think will work best with a 3:55 rear end gear?

 

You can make up half the difference between a 3.08 and a 3.55 by putting a rear tire on that's 1.8" taller.
I had 4.11's in my blue 66 for a long time. I used to buzz that 425 at 3,000 rpm from Pa to Bowling Green and back. It was happy as could be. When the speed limits went up from 55, it was a different story. Got 3.42's now.

 

2004R is the common choice these days.

 

Thanks, the guy's I will start with a taller tire and see how it goes. And if that doesn't do it then I will go to overdrive.

 

Maybe go to a 15-inch tire and repair St ST400

 

What size tires are you using now?
One of our board members, Yardley, puts some tall 70's on his Riv for extended highway trips.

 

How big of a wheel well does a 65 have? I used to run some 265-70R15 tires on my car that were over 29.5" tall and they made the 4.10 gears a lot more livable.

Now I have 3.73 gears and a Turbo 200-4R with 275-60R15. I wouldn't trade it for anything short of a 600HP-capable CVT (none exist that will bolt to a BOP bellhousing to my knowledge).

The spread on the T200-4R is really sweet. If you go that route, get a good lockup torque converter. It is like an extra gear.

 

THANKS GUYS

 

Hey guy, 's I decided to go with a 7004R overdrive trans I was wondering what torque converter to use. I have stock 430 with Comp cam 260H-10 duration @ .050 212 intake and 212 exhaust is my cam specs. I have 3;55 gear in the rear and was looking find what would be the best stall speed to use with this combo?

 

If you are going with a lockup converter, you will be able to overcome any misses you might make with the converter. With a cam like that, it sounds like it is pretty mild. I had a Comp Cam 268H in my 455 and it was hard to tell there was much there. If it was like mine and idled at 700RPM and pulled from 1500 to 5500, I'd suggest you keep the converter pretty mild as well. Definitely nothing over 2500 behind a big block. I'd prefer a custom converter sized to your specs if you have the budget.

Might I ask why you are going 700-R4? You will have to use an adapter plate, right? A 200-4R bolts up and does great.

 

As with any build you the driver need to give the vehicle a purpose...WHAT is this cars purpose. DRAG race street, freeway. fuel mileage... ALL these things come into play. Decside where the vehicle will spend the majority of its time and that will answer your questions.
I went with 2000 stall with a 272 cam crane HMV cam (212 duration at .050 area) in a Chevy Big Block 454 10-1 motor stock 2.06 in 1.72 ex performer intake 750 holley (71 Monte SS) 3.55 gears and 700r4. I loved that combo for all driving ranges and some strip action.
After 25years I rebuilt the 700R4 and went with a 2500 stall and now even at the track the tire blow right off... HARD to drive it in a street tire class blowing the tires off. 2000 was not as hard a hit.

Sooo if that helps at all for some choices ...take it and run with it. Jim

 

You do not want to blow past the torque you are getting so as stated nothing more than 2000 stall with that cam or you are wasting torque band.

 

Hey, guy'sorry it took so long to reply had to step away from my car for a while. In my 1965 Skylark, I went with s 430 bored 30 over with Comp cam 260H-10 duration @ .050 212 intake and 212 exhaust is my cam specs. the stock ST400 trans. I have 3;55 gear in the rear and was looking to find what tire height to run right now I have 215/70/14's and my RPMs are up there even at 50 mph. I need to know what size 16" tire I can run ( and what height ) to get my gearing between 3:30- 3:42. I have no Idea where my gear ratio is present with the 14-inch tire.

 

Also not sure what stall speeds the St400 's are?

 

The 14" tire is only 25.85" tall tire. With 3:55 gears at 50MPH, you would turn 2325 at 100% lockup. With a loose converter, that would be closer to 2500.

Going to a 245/60-15 tire would raise it to 26.5" tall and make it 2250, dropping it 75 RPM. If you can fit a bigger tire, like a 225/70-15 at 27.4" tall, that would further drop it to 2175 RPM. That's effectively dropping it to 3.35 rear gear ratio.

Here's an online spreadsheet I use to play around with those sorts of things. Useful Auto Math

 

Thank for the help, I will let you know what I come up with

 

If I remember correctly the 65 skylark has a smaller wheel well. So I do understand your dilemma. There is a on line tire size comparison for you below.
link - https://tiresize.com/comparison/