Cool bean

It's time to pick a torque converter and I could use your help.

My application will be spirited driving, cruising, hiway-roadtrips, stop light to stop light, and maybe a trip to the track once or twice a year for fun.

Here is what my setup looks like:
1974 coupe with stock suspension.
350, 4-bolt main, .030 over.
Aluminum heads, (Patriot Freedom 2180). 64cc chamber, 190cc intake runner, 2.02 intake valves.
Roller rockers, 1.5's.
Comp Cams 12-209-2 (219/229 @ 0.50 lift)
Long tube headers, 2 1/2" dual exhaust.
Electric water pump, fans, and electric fuel pump.
Holley 750, mech secondaries
RPM intake
700r4 / 3.08 rear / 245/60r15 tires

Cam specs suggest 2000 - 2400 stall converter. Would you suggest anything different and why? I have a 2800 stall speed I could use but I think it's too high. Thoughts?

REELAV8R

I would agree. With the 700r4's lower 1st gear you would not need as much stall.
Your ratio is 9.39:1 in first gear with the 700r4 and the 3.08.
Much better than the th350 which is 7.76:1 in first gear.
I have a 2600 stall with my 350 and similar specs. really could use a 3.55 out back or a 4 speed auto.
Seems like 2200 or thereabouts would work well to me.
where does your cam start to come on? That's what I would shoot for or slightly higher.

Cool bean

On the website stated range of the cam is 2000 to 6000 rpm. The motor is not in the car yet don't know what it feels like.

toobroketoretire

High stall torque converters are useful for drag racing only so if you don't intend to drag race I suggest you use your stock torque converter. But if you decide you really want one I'd recommend a 2000 rpm stall.

Aggitated Monkey

If you cam will have good street manors with the recommended 2000 stall I would go with that. In my fresh install I have a larger cam and both the engine builder and Trans builder recommended a 2200 stall. Haven't driven it yet but was told when put in gear it will feel normal. That it will drive nicely. I was also told with left foot on break bring RPM to 1000 and dump the brake gas to floor "it will launch violently". Just what I wanted. Drivability and all the power when I want it.

Street Rat

Imo it is best to consult with the torque convertor gurus who make these things. Give them all of your specs and they will suggest or build a convertor for your application.

REELAV8R

Reading the info on that cam on summit I see that it has increased lift and duration on the exhaust side. That is going to increase your overlap considerably, reducing bottom end power and making idling more difficult.
Given that I would bump you stall up to 2400 or so.
The higher stall is going to make it easier for the engine to idle and get it deeper into the meat of the power band. Both would be desirable for this cam.
Is there a reason you want both more lift and duration on the exhaust side?

Cool bean

Good question, @Reelav8r. I dont have a good answer; I bought this engine from someone who had it in a '64 and is upgrading to an LSx. It was "close enough" to the build I envisioned so I went with it. With that said, I ask for advice from a friend who's been racing for years here in S. NJ, and he suggested using the tc i have, and if i feel the need to change it, then talk to the folks that build them. He also said that those heads could probably support more power and that a different cam might be something to consider. Given that, and the thoughts you shared, I think it wise to consider it an option. After all, isn't putting smiles on our faces the reason we do this? I think for now I will use the 2800 stall converter, and will swap it and the cam out later if 'needed'. Thank you everyone for comments so far, this is a fantastic education.

AboveTheLogic

All I can add is that I put a 3,200 rpm stall converter on my otherwise stock '94 LT1 camaro a few years ago and absolutely loved it. Power whenever I needed it. It was a lockup converter so I had really good freeway RPMs. Not sure if you could do a lockup. Without the lockup capability I wouldn't have gone nearly as high.

bluedawg

2400 rpm. Higher rpm stalls arn't just for drag racing, matching the stall to flash slightly above were your engine starts to make good torque makes the driving experience so much better and given your lock up converter it won't hurt your cruise experience at all. That's pretty much a wife's tale about just for drag racing, it needs to match the rest of the combination and if it don't it detracts from over all performance, that's why cam manufacturers recomended a converter to match and work with the rpm range of the cam. Although 2800 is a little high, it would work, but 2400 would be better.with the 700r4 a set of 3.55's or 3.70's in the rear would bring it together even more, with that cam id go 3.55. With comps xe262h I ran a 2400 and loved it. Further more, spend the extra money and get a 10 inch converter with a forged shell with lock up, the smaller diameter will reduce rotating mass and add to horsepower to the ground.there's a company up here in Alaska called Pork's Torques if you Google them and ask for porky he'll get you on the track.

7T1vette

I can echo the advice above: figure out what BRAND of torque converter you want to buy, then call their tech line and pose your questions to them. They have all the 'tools' available to analyze your needs and match them with the proper converter.

We all may have suggestions for you. But, the 'experts' are the best ones to ask.

P.S. Don't buy junk from the chain auto parts stores. You will end up "getting what you pay for".

gkull

I debated even answering this because of all the dumb advice given on this forum

But in the 80's the rage was going to a 700R4 because of the OD. So I did it on my 79. equipped with 3.55 rear. The first thing I noticed was the big jump from 1-2 and the way over geared 4th.

So I got out the tire dia/rear ratio and engine rpm calculator and determined that for what I was doing 4.11 was the best option with my hot rodded 355 ci motor

In retrospect a 3.90 is the best option. so from the 80's to the 2000 I drove over 100,000 miles in my vette with 4.11 and my 700R4's

As to TC's spend the money and get the most efficient on the market. I had lockup in 4th gear only. I had the multi lockup clutches giving you more surface area bigger pumps and the racing 850 hp model 700R4. Nothing ever killed it with big slicks drag racing. with 3800 stall 9.5 inch TC Vigilante and Art Carr.

9.5 inch is like putting a lighter fly wheel in. I used 168 tooth fly wheels SFI rated and a gear reduction mini starter

3.08 is just stupid OD is so out of bounds that you don't get better milage

AboveTheLogic

I noticed some relatively high stall converters installed in some late model econoboxes I've rented over the past couple of years. It seems that the automakers have picked up on that part of the equation with designing modern drivetrains. Higher stall with electronically controlled lockups that seems to have different engagement rates.

toobroketoretire

Yes, and when you want to drag race your car you match the flash stall with the engine's torque curve, huh? But for non-drag racing you don't give a rip about your flash stall.

gkull

Highly efficient TC's it doesn't matter if the are rated at 3800 stall for your TQ when you order it even without lockup because under very light load like cruising down the freeway at 70 mph on level ground the slip in OD I saw was only a couple hundred rpm. Go to the Precision industries web sight and check out the 9.5 inch.


old school crap that I have owned on various cars like B&M street fighter and Saturday night specials just plan suck. If it is rated at 3000 driving around in top gear the motor is spinning 3000 unless you go faster. You get what you pay for.

To the poster you want to have your 700R4 modded for no kick down function so you can do WOT in 4th gear. At some point as power goes up even the 3 or 5 lockup clutch units fail. So I drove around for two years with a 3800 stall and no lockup clutch. some of my motors exceeded 20 mpg on trips even with 4.11 rears

REELAV8R

It's worth a try. You already own it so why not. Might find that you like it.

The stall on a torque converter varies as it is.
It may be rated at 2800 stall but that is based on some torque number at 2800 RPM.
If your torque is lower then it may stall at 2600 for you. Or if it is higher then it may stall at 3000 RPM.

Mine was rated at 2200 stall. It stalled at 2400 on my stock motor. Now on the rebuilt motor with more power it stalls at 2600. All the same torque converter. So you can see how it may vary despite the rating.

Aggitated Monkey

Here is the Howards cam I have:

PART # 180345-10; VALVE LIFT WITH 1.5 ROCKERS : INT .565 / EXT .580; DURATION IN DEGREES : ADVERTISED - INT .300 / EXT .306; DURATION @0.050" : INT .245 / EXT .253; LOBE SEPARATION ANGLE : 110
Trans: 700R4
Gears: 3:70
Recomended TQ Converter is 2200 stall. Both builders (engine and trans) recomended the same. No reason to overthink this.

gkull

How many ci do you have and is that a h-roller? That is a lot of duration even in a 383

AboveTheLogic

This is true. Fluctuations in power/weight make a difference, too.

I used to have a 1988 Jeep Cherokee 4.0L that I stroked to a 4.6L. Suddenly the torque converter flash was noticeably higher than it was wit the 4.0L since the 4.6L put out something like 80 lbs more torque at low RPM.

Aggitated Monkey

383 Stroker, full roller, 10.5:1. Dynoed 496hp@6200 with 468tq. Headeds are 200cc/68cc with 2.02/1.60.

Anyway to help the OP it was recommend to run a 2200 stall.