The torque converter is really part of the transmission, not the engine. The converter should stay with the trans.
So then the question would be will the stock converter bolt to the 350's flex plate?
I believe it will no problem.
Be sure to use a flex plate from the 350 engine you are using, not the 225's, as they are balanced way different.

As far as torque multiplication for low end grunt the stock converter should be fine, but -
If you want to run the engine a bit faster where the torque is higher (and the V8 doesn't have the bottom end torque like the odd fire,) then you could go to a higher stall speed converter. It would be sort of like slipping a clutch until the lock-up speed is reached.

You might consult the "Master", Art Carr. He's somewhere in Vegas, probably has a website.


98% is Understanding it
Just throwing parts at it doesn't solve anything.

 

Okay I gotta disagree a bit on this one, (sorry RRich).

1) I know the 225 has good torque, but the 350 should smoke it big time. For model year 1970, the 225 Buick puts out 235 lbs. torque at 2400 rpm. The 350 Buick puts out 350 lbs. at the same 2400 rpm. The 225's bore x stroke is 3.75" x 3.40". The 350's is 3.80" x 3.85". I've always been told that an engine that has more stroke than bore will produce more low-end torque. Dismiss me as a looney, but I tend to disregard HP figures on any engine and focus on torque in the 2500 rpm range to judge the real useable power of an engine.

2) I got sucked in to trying a smaller convertor on my '76 Waggie w/AMC 401 to get the engine in the peak torque range quicker and boy, what a mistake that was. There are those that like it, but I hated it so much that I had it yanked in favor of an RV-type convertor. What I couldn't stand was when you eased into the throttle from a stop, you just sat there while the engine kept winding up until finally when enough rpms came up you'd start to move. The slipping clutch analogy fits perfectly as long as slipping longer than normal is added. Something that's okay in a few instances, but not something you'd want to do all the time. The more the slippage in the convertor, the higher the transmission fluid will be resulting in a shorter transmission life.

3) There seems to be two Art Carr companies. Art Carr Performance Products is in Abiline, TX, http://www.artcarr.com and Art Carr Transmission, (billed as the real Art Carr transmission company, but I'm thinking that this is the business he sold and then started the other), is in Huntington Beach, CA, http://www.artcarrtransmission.com I'm sure both companies sell some good stuff, like low gear sets, HD sprags and clutch packs for the TH-400, but they also sell stuff that will do more to annoy than help, like smaller convertors and shift kits that will jar your teeth out that are really only suitable for racing applications. Be carefull on how far you go with the juicebox tranny. The basic design of the TH-400 is a pretty sound one that can be made better with subtle refinements.

3) When I had my TH-400 rebuilt in my '70 Waggie w/Buick 350, I went with HD steels, clutch pack, torrington bearing and sprags. Put in a rebuilt Allison torque convertor #TC-275, (this is either a 12" or 13" convertor), and other than wishing I had an extra $650 to blow on the low gear set, I'm extremely happy with the transmission and wouldn't do it any differently.

Not trying to say that other ways are wrong, but with past experience I'd just like to pass on my two cents. But in my case I usually wind up redoing everything twice to make up for trying to improve good designs too much. I'll try to get down from my soapbox now as long as nobody brings up the subject of performance cams.

Tim
'66 Jeepster Commando w/Buick 252/4.1L V-6
'70 Wagoneer w/Buick 350 V-8
'76 Wagoneer w/AMC 401 V-8 (sold)

 

Tim - you aren't disagreeing with me at all. A converter with a high stall speed is a pain to drive normally.

When I was refering to low end torque I meant really LOW RPM, like 400 or so. At 2000 RPM or more the 350 will make the odd-fire look like a lawn mower. The little odd-fire will pull nicely when the 350 just wants to stall at the really low end. I'm contantly amazed at the odd-fires sub idle torque. That low pull ability really helps when you have the D20 with it's high geared low range.
But - there's an awful lot to be said for sheer power like the 350 has too.

A stock converter's stall speed is usually just about the same speed as normal idle, just barely higher, that way you can sit at a stop light without fighting it from creeping. As soon as you get off idle the vanes start transferring power, at around 1100 RPM you have near 100% lockup.

To "cheat" a little to get more torque to the wheels you can use the higher stall converters. What happens then is as you rev the engine up not much happens till you get to the stall speed, like 1800 (like slipping the clutch till then) then it starts to hook up. The cheating part is by the time it starts to transfer significant power the engine's revved into it's power band. Great for "Stomp &v Steer" racing.
It seems like that may be able to help in rock crawling to overcome too high a gearing, but it would become a bit throttle sensitive too.
If it's for street use it's really a pain if the stall speed's very high. You push on the accel pedal, nothing happens, you push more, then suddenly it goes. Normally in drag racing the technique is to power brake it while revving into the low end of the power band, then launch from there. (I'm explaining more to make it make sense for neophytes.)
Yes, it runs much hotter too.

Using a smaller converter - not familiar with that one - the high stall converters I've used were all internally modified, essentially the vanes were milled down and a different stator used (proper term? - I'm not an auto trans guy, I leave that to the pros). If a smaller converter is used, wouldn't that still have the same stall speed as stock? Seems like it may hook up quicker?

I built a drag car for a guy that had a converter with a 4500 RPM stall. I didn't do the drive train, just the frame and suspension so that wasn't my choice. It was a funny Mustang, powered by a 289 - he said he'd red line it at 11000 RPM. I didn't see it run, but he wrecked it first time out. When the engine let loose it nearly cut the car in half - not fun.

Last I heard Art Carr was in Vegas, but I lost track of him years ago. When I was in high school he was in Arcadia, near the school - that was when he was first getting into racing. I used to hang around his shop learning and cleaning up for him - certainly learned how a mop works! Huntington Beach, I'm not far from there, think I'll look him up - wonder if he'll remember me.



98% is Understanding it
Just throwing parts at it doesn't solve anything.

 

There are a few ways to increase stall speed, but all essentially reduce the amount of bite/efficiency on the vanes/stators. The only way I kinda understand this stuff is relating it to airplane terms, so I hope I don't put anyone to sleep. The pitch/size/mass of the vanes/stators, (propellor), determines how much slippage and pull there will be. Now a torque convertor is really a turbin, meaning there are two sets of vanes/props to turn. One set hooked to the engine that after moving enough fluid will in turn move the other which powers the transmission. Okay, four ways to raise stall speed: 1) mill the blades as RRich discussed, which reduces the area of the vanes/props, 2) reduce the pitch/bite of the vanes/props, which is what might be termed as flattening them out, 3) reduce the diameter of the convertor, which in turn make for a shorter set of vanes/props, and 4) any combination of the previous three.

Convertors are very interesting in that they can be tailored to any degree desired. What works well on my Waggie w/350 would probably not work well behind a Jeepster w/225. I think the stock convertor for the Jeepster needed to be a bit higher stall as it seeemed to bog a bit much from a stop.

Back to the original post, I think the convertor I have in my Waggie would be a good choice for you if you put the 350 Buick in your Jeepster. At least, I think it'd be a good starting point. If you don't plan on replacing with a rebuilt, right now, try the stock Jeepster convertor. Chances are it's the same part used in the 350 Waggie.

Tim
'66 Jeepster Commando w/Buick 252/4.1L V-6
'70 Wagoneer w/Buick 350 V-8
'76 Wagoneer w/AMC 401 V-8 (sold)

 

FWIW, I'm using the stock TH400 & converter from a V6 Jeepster in Project Mossy. We did however, use an AMC adaptor ring and a 304 flexplate.
Hopefully, it'll roll in the near future and the results can be posted. According to Toad, they're all the same tranny and 3bolt converter. I actually counted "ribs" (should correspond to vanes?) on my convertor and they matched the pile of convertors he had exactly.

Caver Dave
'72 Commando "Project Mossy"

 

My guess is that Jeep used the same convertor for all applications in their TH-400's, regardless of how heavy the rig or how big the motor.

Tim
'66 Jeepster Commando w/Buick 252/4.1L V-6
'70 Wagoneer w/Buick 350 V-8
'76 Wagoneer w/AMC 401 V-8 (sold)

 

Tim - question - since you have a good "handle" on it.
Converters have always been a mystery to me, in fact, all the automatic internals. Never took the time to really learn about them, always depended on "experts." (But then, some "experts" really aren't.)
I usually tried to let the customer decide what he wanted so I didn't have the responsibility of a mistake. The secret of success I believe is not to know it yourself, but to know who does. I pointed the customer to the "experts."

Something I've noticed and wondered about - Seems like all automatic trans guys have a southern accent -- why is that?

On the serious side.
A smaller converter diameter - I can see how it wouldn't transfer power as effectively, but wouldn't it have a sharper pitch to compensate for the smaller area?
Wouldn't the smaller ones still have the low stock stall speed designed into them originally?
Wouldn't the smaller dia ones be for smaller horsepower engines (in stock form?) I would think it would be like clutches, tiny clutches can't hold on to higher HP. (Like a Toyota clutch behind a strong big block - makes for a good barbeque.)

It's always amazed me how they can slip (stall) at lower speeds and supposedly achieve near 100% lockup at top end, supposedly better hookup than a clutch for full power (big power) transfer.

What are your thoughts about how a high stall speed would work on a crawler, designed specifically for that purpose alone? I'm still not locked in yet on mine.
Probably going with a Quad 4 so it needs an adapter to any rear wheel drive type tranny anyway. Quad 4 likes revs, does not like to pull on bottom end, but let it turn and it's awesome.
Some adapters are available, but probably will have to make one.

Glad to know Art is local, I'll try to see him this afternoon.



98% is Understanding it
Just throwing parts at it doesn't solve anything.

 

RRich:

I would say that my good handle on the subject is more like a minor clue. What goes on behind the torque convertor is all very mysterious magic. Probably Wizards and Fairies back there, for all I know.

I'll try to answer your questions the best I can. Unfortunately English is the only language I can communicate in fluently, but do a weak job at getting my point across some of the time. Here goes:

A smaller convertor, (diameter), would generally have the same pitch as the larger convertor. Since there's less mass to move, it would have a higher stall, remembering that on the back turbin blade, it too is smaller, but has to move the same internals in the tranny to get the car to move. Of course, there's a myriad of variables on how that smaller convertor could be made. It could have even less pitch/bite/flatter or it could have more. Theoretically, you could increase the pitch enough to compensate for the smaller diameter, but at some point, there would be too much stress on the blades, unless you went to exotic metals. Also, regardless of pitch, you still have a smaller diameter container, so to speak, which holds less fluid, which will cause the tranny to run hotter. The smaller the convertor, the larger the cooler you need to compensate. In my case on my '76 Waggie, I tried a 10" convertor that was advertised to increase torque. It was really designed for a souped up motor that doesn't develope any power until above 2500 rpm, right where the majority of us tend to peak out. I talked the manufacturer, (TCI), into exchanging it for their RV convertor, which was 12" or 13", can't remember. Much better. When you stepped on the gas from a stop, you moved. The 10" was like a clutch that was worn out slipping waaaaaaaay too much before you'd start to move.

You can get anything from A-Z in a given size of convertor. Kinda like the variables for cams. Two convertors of different diameter with the same stall speed could have different results in power delivery. I think they are rated statically and not for the application of your particular use, which could vary depending on the engine and the weight of the vehicle.

Yes, a smaller diameter, generally, for a smaller engine. But, in the case of the stock Jeepster, I would personally rather investigate in a stock, (12" or 13", which is it, anyone?), with less pitch, going back to that greater fluid capacity thing, running cooler. This would be rated in stall speed. I believe the stock convertor's stall speed is in the 1200-1600 rpm range. This works great for a 350. My guess would be a 1600-1800 stall speed would be less bog for 225/231/252 V-6's. I switched to a 700R4 in my Jeepster, which is the equivallent to a TH-350 w/o.d. It has a smaller convertor, but can't remember what diameter. I do remember the drag on the 225 and 252 motors when I still had the TH-400 in it.

As far as lockup goes, my understanding is there is always some slippage in the older non-lockup convertors used in TH-350's, 400's and other brands. This is why highway mileage is always better with a manual tranny. The newer trannys w/lockup narrows the gap, but still there's slippage until you get thru all four gears and it locks up.

The greater power from a juicebox comes at lower rpms where the slippage causes that torque multiplication thing that I don't entirely understand. This is why on new vehicle purchase, you always get the automatic with the HD towing package, I believe. The juicebox will pull more weight than the standard manual.

As far as the crawler project goes, I'd opt for a lower stall convertor, (stock, but H.D.). You've probably seen the competition rock crawler buggies out in the desert, I'd think. I know that the trend is to go juicebox over manual these days, probably because of that torque multiplication thing and one less pedal to operate. Are they winding their engines up a lot before they start to crawl? If not, then they are using stock stall convertors, most likely.

Quad 4. Isn't that a Kawasaki or something?

I've been a southerner all my life. Lived in southern CA, southern NV and now southern WA. Can you detect my southern accent?

Let us know if you run into Art Carr and what you learn. I'm sure he's got more knowledge on juiceboxes in the tip of his pinky than I have in my whole empty head.


Tim
'66 Jeepster Commando w/Buick 252/4.1L V-6
'70 Wagoneer w/Buick 350 V-8
'76 Wagoneer w/AMC 401 V-8 (sold)

 

Tim - Yes, you are definatly correct, thanks.
I called information - Huntington Beach - Art Carr Transmissions found him.
Went to see him today. I don't think he really remembered me, just faked it a little - that was a loooong time ago - centuries.
Anyway, he's the real, original Art Carr. There are several copy-cat transmission shops using the name Art Carr, but only one real one. He just got back in business a couple of months ago - have no idea why or where he was gone to - not my business, just glad he's back.
He explained about the different ways of getting high stall speeds.
Essentially the way he does it is with the vanes in stock configuration at the stock angles but shaped differently, depending on what's needed - as opposed to B&M that puts the vanes backwards to let it slip. Others cut the vanes to do it.
All converters slip - never achieve the 99% lock like I thought, his just slips lots less than the others. He told me about how dyno tests (he's got a transmission dyno - didn't know they existed - saw it from a distance) tests showed on his converters a RPM loss of 200 RPM at 4500 RPM (4% loss) with a heavy load, where the best competitor B&M loses at least 700 RPM (more than 15% loss) under exact same circumstances. That creates much less heat and more torque to the wheels.
I explained what I'm building, he's intrigued - he said a higher stall speed would be just the ticket, as the Quad 4 (GM, Pontiac Aluminum 4 cyl, DOC, DIS, PFI and lots of poop) is a high RPM motor - all were front wheel drive tranverse mounted. He recommended a T-350 - I'll have to build an adapter - no biggie compared to some of the other stuff I need to fabricate.

He's a super nice guy, easy to talk to, and extremely knowledgable. I also met his VP of Manufacturing, Hector, another easy to talk to guy. Hector was the chief engineer for B&M till recently. Art's got a good team together there. 800 - 278-2277 www.artcarrtransmission.com

There's been talk about low gears for the T-400's, he's got them, as well as shift kits, rebuild kits and the trick stuff to make your tranny's work better. Also can help with flex plates.
OK, commercial's over.

Art will build my tranny and converter when I'm ready.
Then I stopped by Joe Jill's place, he's going to build the Quad 4 for me - my engine guru.
Then I stopped by another friend's place - explained what I'm doing. He wants in too. I might have Mike do some of the welding. It all started off as a little project built and funded by me, but it's getting out of hand. Looks like I won't be doing much of it myself, just making it happen.
Now all I need is a diff guy and someone with a Mandrel bender.

Now there is someone else I'd like to track down - I lost contact with him years ago. He was National Sprint Car Champion - I think 3 years running - late 60's, early 70's.

Anybody know the whereabouts of Buzz Gregory? I'm sure he's still involved with racing somewhere. Once it's in your blood ---.

My first wife and I used to pal around with him and his girlfriend. I got rid of the wife, he got rid of the girlfriend.
(No, I'm not looking for him as a driver - that's my job! -- at least at first.)

And you are right about the smaller converters having a higher stall. You gave a great explanation why too, thanks.
Now I can truly say "I don't understand all I know."

98% is Understanding it
Just throwing parts at it doesn't solve anything.

 

Sounds like you had a good day. Keep us posted on your progress.

Tim
'66 Jeepster Commando w/Buick 252/4.1L V-6
'70 Wagoneer w/Buick 350 V-8
'76 Wagoneer w/AMC 401 V-8 (sold)

 

Just in case somebody is trying this same conversion, the 350 buick flexplate WILL NOT bolt to the Jeep 400 torque coverter, it has the small pad pattern and the Jeep 400 has the large, I found this out after having my new motor completely in hooked up and ready to go!

Scotty Dalton
She Thinks My Jeepster's Sexy!
70 in Boone, NC

 

What did your 350 come out of? If a Buick, then chances are that it had a TH-350 transmission hooked up to it as GM generally put TH-350's behind small blocks and TH-400's behind big blocks. I would think you shouldn't have too hard a time locating the right flexplate. If no luck, then TA Performance in Phoenix should be able to fix you up. If your 225 flexplate will fit on the 350, then you probably could take it to a machine shop and have it re-balanced for the 350.

Tim
'66 Jeepster Commando w/Buick 252/4.1L V-6
'70 Wagoneer w/Buick 350 V-8
'76 Wagoneer w/AMC 401 V-8 (sold)

 

I know Scotty and I've had a Jeepster with 225 and a T-400.
I would think that when he puts it in gear/P/1 that he wants it IN gear and ready to pull. Either motor has great torque at low end and should be engaged at LOW rpm's, plus he's got low gears in his t-fer case.

Richard Queen
PROUD! member of the EASTERN CHAPTER!

 

I was thinking of just getting a small bolt pattern torque converter from a 400, the 225 is the large pattern with about 10.75 inches between the bolt holes, but I may have to get another flexplate, the 225 plate will bolt up and LOOKS the same, but it would need to be rebalanced for the 350.

Scotty Dalton
She Thinks My Jeepster's Sexy!
70 in Boone, NC