Thread: Help me pick a torque coverter: Turbo 400 behind a 396

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Hi all!

Getting close to bolting my TH400 up to my 396. Still a few weeks to go. Details:

1: I'm not building a drag car. I'm going to cruise in this old girl. That said, it will go down the quarter mile a few times just to see what I've built...

2: 1968 Camaro

3: Rear End: 12 bolt posi. Gears will be either 3.55 or 3.73 (likely 3.55)

4: Engine Details...
- 396
- 11.1 compression
- heads: Edelbrock Perf RPM Oval Port 290CC
- cam: Howards roller 600/600 286/286
- Intake: Weiand Stealh
- Carb: Holley 800CFM 4150 double pumper

Question: I'm in need of a torque converter with a nice stall. I have 2500 - 2800 RPM stall in mind. It will be a street cruiser with a couple passes on a strip just to see what she'll do. What do the experts say about a nice stall?

Thanks![/LIST]

2800-3000 rpm stall.
Here's what I'd be thinkin'.......
https://www.summitracing.com/parts/bmm-20481/overview/
What kind of fuel do you plan on running?
What's the squish/quench measurement?
You're gonna need more gear than what you're thinkin'.
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I think that for street driving that lower rpm converters are the way to go-less heat build up, better milage, etc--anyway, if you step on it , its all over within by the time you get your foot all the way down on the pedal so why????????

Thanks for the replies!

Definitely not going lower than 3.73.

Same fuel I ran on this motor with cast iron heads. 93 octane. I'm going from big rectangle port heads and 109CC chambers to smaller oval port heads with 110CC chambers. Same size intake / exhaust valves.

I changed the cam from a big solid lift cam to the roller I noted above.

I changed intake from a Performer to the Stealth.

Thanks!

Good luck. With the cat piss fuel available today you're going to need it.

My choice wouldn't exceed 2K maybe 2300 rpm. max, there's so many variables for "street driving". Don't believe you'll enjoy spinning a lot of rpm to get across an intersection on a slight grade. How are you cooling this trans.?

I'm fortunate that I have a good friend who is a really first rate automatic transmission technician, I seldom run an automatic on the street but when I do I take all my engine specs to Jim, he calls the torque converter shop he does business with and gets one built to match the engine pieces! A 2000 advertised stall converter behind one engine can actually stall at 1500 rpm, but on an engine with a different cam, heads, compression ratio, quench, etc. it might not "hook" until 3,000 rpm.

Your cam's profile says it's operating RPM range is 2,500-6,100. I’m not an automatic transmission expert by any means but I recall hearing more than once that the advertised stall speed of your converter should be at least 500 rpm higher than the beginning of the camshaft’s power band - in your case that would be 3,000.

I also think you may be disappointed with the 11:1 C/R and pump gas (unless you use an octane booster – which can also be a crap shoot with today’s pump gas) with your cam selection with less than a 3:90 (preferably a bit more) rear end. If you want a boulevard bruiser, I’d go a 4:11 and maybe tame the cam selection down a bit to one that come to life around 1,800RPM.

Regards,
Glenn

Badda Bing, Badda Boom. Only thing I would add to Glenn's disection of your build is that if you go with less cam, you will likely have to go with less static compression ratio. They go hand in hand.
https://www.crankshaftcoalition.com/..._compatibility
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Yup - what Tech said.