Torque Covertor Selection Advice

[LR1970]

So the next question is about convertors. I just watched a video about convertor selection. They suggested to choose a stall speed 500 rpm above cam start range and that BBs stall roughly 300 rpm higher because of more torque produced.
So if my cam start range is 2600rpm, I will choose a 3000 rpm stall.
Then the full lock up of the stall will be roughly 3000 rpm + 300 = 3300rpm, 700 rpm above the cam start range. So then do i choose a 3500 rpm stall?
Or a 2500 rpm stall convertor + 300 =2800rpm, 200 rpm above the cam start range.
Or are the numbers not this precise and each engine can be different and the stall selection can be trial and error? I just don't want to spend money on something that will not work right.

My set up is

72 Roadrunner
28 inch height tires
440 + 30
906 heads with OS valves and porting
headers and 3 inch exhaust
Performer RPM intake
750 Holley performance carb
Cam ?
Stall?
Rear gear ratio?

I need to understand all these things before cam, convertor and rear gear selection.

 

[67 B-body]

Is this a street cruiser or strip bruiser?
You dont' want your converter slipping while at average cruise RPM if this is for the street.
With that being said,,, your list of goodies should include compression ratio..... When you design an engine build, make sure you think of everything as a package deal..... Your cam selection will be impacted by the amount of compression your engine can produce, you already have an intake selected so this narrows down the playing field for camshafts that work best, the carb has been selected once again narrowing the window even more..... Then your rear gear and finally converter selection can be made....
Happy Moparing!!!

 

[Greg Ducato]

Your converter stall speed will ultimately depend on your cam specs, especially duration at .050 and lobe seperation. A converter builder will need this along with as much info on the vehicle specs as possible to build you the best possible converter for your engine and driving requirements.

 

[LR1970]

This car is just for the street. I was aiming for 10:1 compression. I already have the intake and carb because I picked them up for a good price. I am pretty set on 3:54 rear gears also. With 28 inch tall tires it will give me 2750 rpm at 65 mph. So I guess that means I need a less than 2750 stall? Same with the cam range? I really don't want to cruise any higher rpm than that. So just need a cam and stall to suit. Any suggestions?

 

[67 B-body]

Does your budget include a roller cam setup? Do you mind adjusting valve lash or do you only want hydraulic lifters?
In my opinion, if you can't go with the roller setup, a good solid flat tappet setup would be next best thing....
Keeping duration down and maximizing lift would be best for a powerful bottom end / mid range RPM engine. This would allow you to run the 2700 rpm convertor.
BTW cam quest software is a free download available fo you to try different cams..

 

[dave5237]

I just put a 2600 stall in my 68 and the spec on the cam was 230 duration at .050 / 486 lift. 440 motor punched out .060, eddy 800 cfm carb. She runs real sweet now and is a cruiser.

 

[Hemi Rebel]

I didnt catch the cam, but it sounds like a 2800 to 3000 rpm stall would be perfect. A street/strip converter is what you want. Under normal driving the converter isnt so loose that you have to get the rpm's up to get the car to move. Thats straight up race car stuff. So dont worry about having a cruising speed of 2700 with a 3000 stall.