Hello,

I have a 77 f150 4x4 with a 351m/c6 and i am in the process of rebuilding the transmission. While shopping for torque converters i narrowed it down to a 1200-1400 rpm stall, and a 1600-1800 stall converter. I am not too savvy on this subject, and i was wondering which converter i should choose. I plan to put 33" tires on the truck, and do the 400 conversion with a mild cam and headers. It will be occasionally used for towing a boat in the 5000 lb area. It will never be used for mudding. I have read in a couple of places that the low stall converter will get me better mpg around town. What are the pros and cons of choosing either converter? Also which would work best for my current state (stock 351m) and possible future state (mild built 351m and possible 400 conversion). Thanks! I look forward to hearing some opinions.

 

I've always heard you want a low stall in towing.
High stall and heavy towing builds more heat in the transmission which can eventually kill it. You can add a extra transmission cooler to help with that.
Picking torque converters and their stall speeds is way more complicated than what I described but generally high stall and towing don't go together.

 

With the way you're going to use it, I would stick with the low stall speed converter, that's all you'll need.
Like 79FordBlake said high stall = high heat build up, something you don't want in an automatic.
You only need a high stall speed converter if you're running a radical cam that develops HP high up in the RPM range.
Driving in traffic and towing will get old real quick with a high stall converter, the excess heat build up will kill your tranny in short order.

 

Thanks for the reinforcement on this i will go with the lower stall.

 

I did a little more research on this, and it looks like the 1600-1800 stall converter is stock for this application. Will the 1200-1400 converter be sluggish on take-off? I think the engine would be fighting the weight of the truck and bigger tires when its not up in the right rpm range. Granted it is only a couple hundred RPM, I just want to make sure I pick the right converter. I plan on installing a cooler anyway, I just don't want to have a truck that doesn't want to move either. Does anyone on here currently run a 1200-1400 rpm stall converter in their rig?

 

All my vehicles have a stock converter except for my 78 Bronco. My buddy that had it before me had the transmission rebuilt and had a custom built torque converter made. The stall on it is supposed to be 1000.
If I were to chain it to a unmoveable object it doesn't take much throttle to start spinning the tires. My other Bronco has more power but if I were to do the same to it it would require more throttle to start spinning the tires.