torque converter question: Which to use?
 

I finally got around to going through the 427 tall deck for 78 chevy 1/2 ton 4x4. I opted to get rid of the solid lifter cam that was in it for a hydraulic cam cause its easier for me to set. My truck has 3.08 gears and 31 inch tires and with the last two motors that have been it i have had lots of problems transferring power to the ground. The one motor with the cam that was installed was recommended that i use a 3500 rpm stall and i also used a 2200to2800 stall behind the same motor. The problem was always the same i couldn't build rpms in the power range before it would shift with the gearing i have in the truck right now. Long story short i am trying to get the truck on the road and be driveable for a while and use it to pull the trailer short distances. I have axles with 4.10 gears that i will be putting in the truck later on this winter along with a lift kit and 37 inch tires. I really don't want to have to drop the transmission out of the truck again to change torque converters when i do this.

I know that 427 tall deck's are known for their low end torque. i just want to make sure of this so i know what torque converter to use. Here are the specs for my new cam. I'm not sure how to read them exactly so i don't know where the power band would be.

Rocker arm ratio:1.7

Lift intake @ valve .475

Lift exhaust @ valve .500

Cam timing @ tappet lift intake 266 degrees

" " " exhaust 276 degrees


I have a stock heavy duty torque converter,

a 2200 to 2800 stall converter

and a 3500 stall converter.

I also have access to a 2000 stall converter.

the transmission is a TH400.

If there is any other information that is needed i will try to provide it the best i can. Any and all suggestions is apprecitated.

Re: torque converter question: Which to use?
 

The torque converter has nothing to do with when shifts occur. Wide open throttle shift point is controlled by the governor in the transmission. You can get a kit from B&M that comes with different weights and springs that allow you to fine tune the shift points where you want them. Sort of like messing with the springs and weights to set your timing curve on a distributor.

Here is a great article that explains the process - http://www.dragracingonline.com/tech...vi_9-bm-1.html

Re: torque converter question: Which to use?
 

Post the make and part number for that cam. The specs given seem pretty mild, but really need to know what LSA is and what duration at .050 is. But just guessing, I think either the stock converter or the 2000rpm stall would be adequate. Going much higher than that it would not be too good for towing.

Re: torque converter question: Which to use?
 

I'm not really worried about shift points per say. Where it shifts is no problem to me. Its just with the gearing and the tire size for the 2200 to 2800 stall to fully engage is 40 mph at 2500 rpm. I can't get the rpms to the power band at the speeds i normally travel.

Re: torque converter question: Which to use?
 

heres the link to the specs on the cam:

http://www.summitracing.com/parts/SUM-K1300/

Re: torque converter question: Which to use?
 

For that cam, use the stock converter.

Re: torque converter question: Which to use?
 

Dont use the stock heavy duty converter (2500-2800) That is too much stall for you. Your power band on that cam is 1000-4500 rpm. I would use the 2000 rpm stall or possibly a smaller one if you have access to it.

Re: torque converter question: Which to use?
 

I am sure that a stock heavy duty converter is way less then 2500-2800...

Re: torque converter question: Which to use?
 

Your right I misread the original post. Definately use the stock converter

Re: torque converter question: Which to use?
 

High stall stock is about 1800rpm. I wouldnt run anything higher than about a 2k rpm stall with that combo. Its going to make a boatload of torque with that cam. The stall converter isnt going to help.

Re: torque converter question: Which to use?
 

I took your guys advice and put the stock converter in. The engine got put in yesterday and i had it running and drove it around the block. Seem to drive fine, jst need to set valves, dial in the timing, and switch out carberators. Then the truck should be running great.