Another Gear Vendors question..

[Thumpin'66]

I have a roots blown small block that I am putting in my 66 Chevelle. I have a TH400 already and a 3.50 rear gear. Rear tire size is 295/45r18. This engine/trans and rear gear combo has been good for street cruising and mid 10 second 1/4 mile passes in my Monte. I am planning more freeway cruising in the Velle and am looking at a gear vendors. I currently have a 3,000 stall. I wonder if I should get the gear vendors and change my stall to around 2,500 to really get the rpms in line at cruise. I have a trans brake and tons of torque so as long as my cam lets me idle on that stall it should be ok? Input?

Thanks,

Russ

[Thumpin'66]

I think I just answered my own question by finding this on Gear Vendor's web site:
Can I run a high stall converter in overdrive with a 3.42 axle?
Yes, this is one of the most often confused questions (even when you ask people you would think would be knowledgeable). Here is the detail. Our example could be this 3.42 Chevy guy. In overdrive he is going to be a 2.67 final drive ratio. He is a Cutlass body with 27 inch tire and so at 75mph in overdrive the motor will be turning 2484 rpm and he has a 3500 stall speed on the back of a pretty nicely built 350ci motor making close to 400hp. 95% of the people you would ask (even tranny guys) would say no-way and yet we know this is an awesome package (drives wonderful, no high temps in the trans etc) why does it work? When his converter was made it was set up to stall at 3500 with 400hp. However if you put 600hp to it it would stall at something like 4500. Conversely if you only put 125hp to it (as when you are just crusing at 75mph not accelerating) then the stall is way down at 2,000 rpm. So his stall with a 3500 converter is not 3500 at cruise because he is not making 400hp. Car drives wonderful. If he romps on it while cruising then the trans is going to downshift to a lower gear and get him into the powerband. (note: read gear vendors passing gear in this section) So, this is why you never lie to you converter builder (because if you overstate your hp you will not get the stall you wanted).
The package of 3500 and 3.42 with 400hp is a sweet setup with a GEAR VENDORS . Without a GEAR VENDORS the trans will not have a great passing gear because 2nd is too low. But with a GEAR VENDORS it will it will jump right into 2nd-over which will rip nicely and put the converter right in the power. You can use this setup as a guidline and say move up or down in ratio related to stall from this good setup with a GEAR VENDORS. Below you will see we have listed an actual formula for Aerodynamic load.
Aerodynamic drag force may be defined as follows:
Fd = (1/2) Cd r A V^2 (1)
where

Fd = aerodynamic drag force
Cd = coefficient of drag
r = density of air
A = frontal area of vehicle, into the direction of motion
V = velocity of vehicle, into the direction of motion


Guess my convertor is good.

[ponchopwr70]

I run a sb chevy with around 450hp, 3000 stall (flash to 3500) with a th350 3.55 rear and 315/35-17. I've gone 12.5 at 108 with this combo. I have no problems at all. I can cruise 1800 around town and 2800 highway. The only thing is when you put your foot into it its kind of lazy so I just shift out. I recommend getting it, I drive my car so much more now.

[turbo kid]

I had a GV before and loved it but I missed the lock up converter.