Why do I want a higher stall TC?

[68Timber]

Originally Posted by slugish

What is the duration on a 268 cam -- Does it vary from manufactureer to another or is it standard-- the reason Iask Idont knowe what cam Ihave . but Ido know its got 224-230 duration with a 048 lift with 1.5 rockers. Its a comp. cam . My stall is shot , but tranny shifts fine . Iwould like to know what stall converter is best for me or do Ineed any at all . Iknow right now that Ican't get any rpms in my power band without the tires spinning with the shot converter Ihave

The durations and lift numbers on your cam are the same as the Comp 268, it may be what you have. You can use the stock converter with this cam, but it wouldn't hurt to put one slightly looser in, no more than 2200 rpm stall, and keep it a 12" converter.

[68Timber]

Originally Posted by vtwinsport

Hey guys, thanks for all the input (ha - no pun intended).
Yes, I don't have a budget nor the inclination for a 700r transplant so I'm sticking with the t350.

Bruiser- Truck has stock 350/ t350 with edelbrock carb, intake and headers with 3.08 rear gears (being changed to 3.42 in the spring), dart iron eagle 67 heads coming (now stock 76cc), comp XE 268 cam is in the garage waiting for spring. Stock converter as far as I know in the transmission.
I have the carb and timing tuned as fine as I can (including jets and springs) and I often have to shift into neutral or peddle the gas to keep from stalling at stop llights with current converter.

What I want is more snort from the line- 1000 rpm to 3000 rpm really and I daily drive this with periodic hwy travels in a week. This will never see the strip and there is a factory trans cooler in my rad already. Is that stock one good enough?
Thanks in advance

Yeah, you'll need an additional external cooler in front of the radiator. A little extra slip = a lot more heat. You can get one for $50 and it's very cheap insurance. If it's struggling at idle, get a good converter advertised around 2200 rpm stall. It'll idle in gear without stalling the truck and the stall speed is still low enough to make use of all the extra low-end torque that cam makes.

I'm going with the Comp XE274H and a TCI converter with an advertised stall speed of 2400.

[68 TT]

Originally Posted by vtwinsport

Hey guys, thanks for all the input (ha - no pun intended).
Yes, I don't have a budget nor the inclination for a 700r transplant so I'm sticking with the t350.

Bruiser- Truck has stock 350/ t350 with edelbrock carb, intake and headers with 3.08 rear gears (being changed to 3.42 in the spring), dart iron eagle 67 heads coming (now stock 76cc), comp XE 268 cam is in the garage waiting for spring. Stock converter as far as I know in the transmission.
I have the carb and timing tuned as fine as I can (including jets and springs) and I often have to shift into neutral or peddle the gas to keep from stalling at stop llights with current converter.

What I want is more snort from the line- 1000 rpm to 3000 rpm really and I daily drive this with periodic hwy travels in a week. This will never see the strip and there is a factory trans cooler in my rad already. Is that stock one good enough?
Thanks in advance

Figure out what your cruise RPM will be on the freeway with your new gears and the tires you will run and set your stall a little below that with the T-350.

The 268 cam can be run with a stock converter but will like something around 1800 to 2400 rpm range. I would go with about 2000 rpm to start with.

When you put in the external trans cooler run it in series with the stock in-radiator cooler so the fluid goes through the stock in-radiator cooler then into the external cooler and then back to the trans.

[Chlsnk]

Originally Posted by BRUISER

The durations and lift numbers on your cam are the same as the Comp 268, it may be what you have. You can use the stock converter with this cam, but it wouldn't hurt to put one slightly looser in, no more than 2200 rpm stall, and keep it a 12" converter.

Why keep it 12" convertor what is the problem with the 11'' and 10'' ones I see for sale.

[3r!c84]

they hold less fluid so they get hotter quicker? idk

[joe231]

Originally Posted by qu1cks1lver56

Wonder where to find one.

you need the whole transmission, not just the converter.
Lots of the mid 80's trucks had the TH350C.

I know where there is a good one for sale locally.

[68Timber]

Originally Posted by Chlsnk

Why keep it 12" convertor what is the problem with the 11'' and 10'' ones I see for sale.

Here's my take on that. Many factors play into true stall speed of a torque converter - it is not a promise that it will flash at 2200 if it's advertised at 2200. The engine power, vehicle weight, and size of the converter all play a part of what the true stall speed will be. Smaller ones are generally looser converters. With a Comp 268 in a truck, you can be reasonably certain a 12" converter advertised at 2200 will actually flash at 2200.

[vtwinsport]

Bruiser, 68 TT, Chlsnk, 78 Chevyrado,
Thanks again, that clears it up. I'll get a little better 2000-2200 converter and add a cooler in series.
Good to know the techs at the speed shop weren't misleading me. They did spec a 2400.
Later,

[qu1cks1lver56]

Originally Posted by joe231

you need the whole transmission, not just the converter.
Lots of the mid 80's trucks had the TH350C.

I know where there is a good one for sale locally.

I have an 86, maybe mine has one and I don't know it?
Is the ECM fuse supposed to be in it for the lockup to work? I took all the electronic carb and whatnot out and idk if it needs any ECM stuff to work.

[68 TT]

Originally Posted by qu1cks1lver56

I have an 86, maybe mine has one and I don't know it?
Is the ECM fuse supposed to be in it for the lockup to work? I took all the electronic carb and whatnot out and idk if it needs any ECM stuff to work.

It just might have the T350C.

I believe it will need the ECM to work automatically but you may be able to wire it up to a switch to lock it manually. I know you can do this with the other lock up trans. I did it with my GN.

Wire it into the brake switch so it disengages when you step on the brakes like stock so it doesn't stall the motor when you come to a stop if you forget to unlock it.

[qu1cks1lver56]

Originally Posted by 68 TT

It just might have the T350C.

I believe it will need the ECM to work automatically but you may be able to wire it up to a switch to lock it manually. I know you can do this with the other lock up trans. I did it with my GN.

Wire it into the brake switch so it disengages when you step on the brakes like stock so it doesn't stall the motor when you come to a stop if you forget to unlock it.

Good idea, I might just try putting the ECM fuses back in and seeing where that gets me. And if that doesn't work I'll try a switch.

[joe231]

It shouldn't have anything to do with the ECM unless it was fuel injected. It is a hot wire that goes through an extra set of contacts in the brake switch that will unlock the converter when the brakes are applied, then through a vacuum switch mounted on the firewall that will only let it lock under light throttle, high vacuum.
Look on your firewall above the brake booster and see if you have a vacuum switch with 2 green wires.
You can also tell easily if there is a white 4 wire plug on the drivers side of the transmission up above the pan flange and to the rear of the shifter.

[qu1cks1lver56]

Alright I'll check that out tomorrow. I know there is a connector on the transmission in the place you described but I'm not sure of the color or number of wires. And I'll look on the firewall for that switch. I know it's got all kinds of junk on the firewall that I want to go through and find out what's not needed and get rid of it.

[68 TT]

Originally Posted by joe231

It shouldn't have anything to do with the ECM unless it was fuel injected. It is a hot wire that goes through an extra set of contacts in the brake switch that will unlock the converter when the brakes are applied, then through a vacuum switch mounted on the firewall that will only let it lock under light throttle, high vacuum.
Look on your firewall above the brake booster and see if you have a vacuum switch with 2 green wires.
You can also tell easily if there is a white 4 wire plug on the drivers side of the transmission up above the pan flange and to the rear of the shifter.

Good info to know. That must be a truck thing since they didn't have CCC carburetors or electric fans like the cars did of the same vintage. Hopefully he didn't remove any of that system. It should be pretty easy to put back in place if he did even without the ECM.

[qu1cks1lver56]

It's been so long since we put that motor together I can't remember all of what we pulled out. It had a stock 305 with the electronic carb and all the other electronic junk. And we pulled that off and setup a holley 600 on it. And then built the 350 that's in it now. It's out in the shop right now, water pump went bad, but I'll look it over when I get out there.

[dbmx66]

it all depends on what rpm range your engine is built for, and what rear gears your using.

[qu1cks1lver56]

3.42 rear gear. engine is built for low end toque. I'd say 6k is the most it should ever see.

[dbmx66]

then i wouldn't recommend it, if you had a nice street/strip motor where the power band of the internals is like 3000-7500 rpm, then i would recommend it.

you want to match it with your cam and intake rpm range. you'll also have to look into ur rear end ratio.

thats not a bad ratio, but if the engine is being used from idle-6000 rpm, you might want to go with a small stall convertor, not like a 3000 or 3500

[spinem]

Originally Posted by Keith Seymore

"Stall" is when you smash your foot on the gas, and smash your foot on the brake and note where your engine rpm ends up (like 2500, or 3000 rpm, or whatever).

(...assuming the brakes hold!)

You want a higher stall mostly for racing or brisk street driving, since it will get your engine rpms up into the power band sooner. This would be important if you are going to a cam or intake/carb combination that doesn't like low rpms.


K

smash what?....no no no, stall referrs to what RPM the car will begin to move at... if its a 500 rpm stall, the car will wanna move even with ur foot on the brake, (given ur idle is above 500rpm) if u have a 2000 rpm stall and let ur foot off the brakes the car will stand still (given ur car is idleing below 2000 rpm)

you will need a higher stall if ur upgrading to a large cam (wont idle)
another bonus is to get the car in the power range immedently (I have a 2000 stall)....

the freeway thing, yes, if u have a 4speed tranny with 4th going 70mph at 1500 rpm and you have a 2000rpm stall, yes, your torque converted will slip, thus causing premature wear, excessive heat and overall bad news.

i think what the person i quoted was trying to say is some people buy torque converters with a stall at their power range.... example:
car makes 300hp at 3,400rpm and 120 at 2000rpm, its a race car.... when u jump off the line, u wanna be making 300hp immediately, no lagging.

keep in mind a torque converter is not like a clutch, it works using hydro pressure, not physical contact of disks.

you should look into trans brakes also, some good stuff there.

[68Timber]

Originally Posted by spinem

smash what?....no no no, stall referrs to what RPM the car will begin to move at... if its a 500 rpm stall, the car will wanna move even with ur foot on the brake, (given ur idle is above 500rpm) if u have a 2000 rpm stall and let ur foot off the brakes the car will stand still (given ur car is idleing below 2000 rpm)

you will need a higher stall if ur upgrading to a large cam (wont idle)
another bonus is to get the car in the power range immedently (I have a 2000 stall)....

the freeway thing, yes, if u have a 4speed tranny with 4th going 70mph at 1500 rpm and you have a 2000rpm stall, yes, your torque converted will slip, thus causing premature wear, excessive heat and overall bad news.

i think what the person i quoted was trying to say is some people buy torque converters with a stall at their power range.... example:
car makes 300hp at 3,400rpm and 120 at 2000rpm, its a race car.... when u jump off the line, u wanna be making 300hp immediately, no lagging.

keep in mind a torque converter is not like a clutch, it works using hydro pressure, not physical contact of disks.

you should look into trans brakes also, some good stuff there.

Keith described flash perfectly...

[qu1cks1lver56]

Well I have a vacuum switch above the brake booster, gonna hook it up tomorrow and see if my 70mph rpm's are different.

[joe231]

cool

[qu1cks1lver56]

inorite?

[joe231]

[qu1cks1lver56]

inorite/i know right lol

Well I hooked it up today but didn't get out on the interstate and couldn't really tell if there was a difference riding around town.

But I did get my serpentine swap done.