Fletchmo72

So, I have a 72 Cutlass Supreme, 350/350. The engine and trans were both rebuilt by the PO at around 100k. Have about 30k miles on them now. Engine has a mild cam and well tuned q-jet. Starts and runs very well. I installed a 3.23 gear with posi last year.
I am unsatisfied with the acceleration from a dead stop. Usually won't spin my half worn 14" tires. Wondering if an upgraded torque converter would help. The current brake stall is only about 1200 rpm. That seems too low.
Thoughts/suggestions?
Thanks, Jack

joe_padavano

A higher stall torque converter will improve off-the-line acceleration IF you are constantly power braking the car when you launch (as in, at the drag strip). The down side is that you will have more converter slippage, more trans fluid heat, and more engine RPMs under other conditions. Of course, this also depends on the converter design. IF the converter stator is designed for torque multiplication, it will help acceleration. If it is a smaller diameter converter, it's probably got too much slippage for you. If this is primarily a street-driven car, ask yourself if you want to make that tradeoff.

Also keep in mind that converter stall speed is not fixed - it is dependent on the available engine torque. The fact that yours stalls out at 1200 RPM tells me that your engine isn't making a whole lot of torque.

Personally, I'd want a converter with the LOWEST stall speed that lets me accelerate. This is why the switch pitch converter was such a good idea.

Fletchmo72

Thanks for the info, Joe. I'm not familiar with a switch pitch converter. Is that something that can be added?

Fun71

I have a Hughes 2500 RPM converter in my car and I really like it. During normal (non-hot rodding) driving it feels about like the factory converter. For a while I had the 2.56 rear back on the car and I calculated ~200 RPM slippage even when the RPM was well below the stall rating. So if you get a quality converter you shouldn't have issues with excessive slippage and heat generation.

olds 307 and 403

Yes, a converter makes a big difference in launch. I went 2200 to 2500 stall, it flashed at 2300 rpm, I did have the better 2004R 2.74 first gear. I could spin for a 1/4 of a block just hitting the gas with 2.78 gears. I went back to my stock TH350 and converter after my daughter ran my 2004R low on fluid and fried it. No tire spin for me either. I swapped that trans, since it was dying for a TH350C, it flashes at maybe 1600 RPM, so it sucks, no tire spin. I plan on the Hughes 2500 stall, it will probably flash around 2200 and with the lock up, have no slippage. Hughes rates their converters at 500 hp, some others rate as low as 230 ft/lbs, a huge difference. Everyone who has the Hughes converter's like them, just be aware they will stall less than advertised unless big power is in front of it.

Fletchmo72

Olds 307/403: So you were using an overdrive trans--200r4--with a 2.78 rear gear, and that worked--it didn't lug?? Also, what would work best with my 350 engine and 3.23 rear gear, a 200r4 or 700r4?

olds 307 and 403

Not too bad on lugging, I ran a short 25" tall tire. The 2004R is a nearly direct swap, the 700R4, it needs mods. Plus the 2004R has a better gear spread and overdrive. Both trans need upgrades. Go with a Hughes 2500 stall.

Fletchmo72

Thanks for the advice. I'm going with a Hughes 2500. Should have it installed in a week or so. I'll report back on how it worked out!

jfb

I can see that you made your decision but here is a idea that works,I have one and it works excellent. call m------o in California and tell them about your combination you will pay a little extra but it will work. they have done the r and d in the past and it is worth the extra for this knowledge,and time saver. I personally do not like to work twice it wastes time and money. I have almost no slippage on the road with a higher stall converter.

Fun71

Prolly better to call a converter company directly.

72GoldOlds350

So, what are the updates?!

BangScreech4-4-2

My understanding from reading multiple negative posts here and many other places is that you should never call M------o in California for anything ever. Period.