kiloman_11

Need to replace my torque converter of unknown make and stall on my 1970 Cutlass S 350 4bbl/TH350 car. Mild cam, 256 gears, cross country car/daily driver. I am looking at the Hughes converters since I see they are supposed to run cooler and heat/longevity is a concern. Any experience with the Hughes GM20 or GM25 converters? Is a 2000 Stall going to be ideal for a highway gear 350 car? Any help and advice is welcome I gotta get this thing put together soon!

Fun71

I have the GM25 in my car and I really like it. If you plan to keep the 2.56 gears then the 2000 RPM converter should work well. Back in the 80s I had a 1970 Supreme with 2.56 gears, a mild cam (.432" lift, 204º duration), and a 2000 RPM converter that worked very well together.

kiloman_11

I see hughes says the stall rpm rating is for fresh big blocks and that small blocks will vary 300-500 rpm lower. What would the GM25 be like in my 350? would it be rough to drive around town, idling in gear and all?

Fun71

Mine stalls near 2400 RPM based on watching the tach while going WOT from a dead stop, but that is with the 3.23 rear gears and a 217/221 cam.

A few years ago I had the 2.56 rear on the car for a few months and the 2500 RPM converter worked well even with that gear ratio. It basically seemed how I recall the factory converter operating during around town, light throttle driving. Regular feeling shift points when leaving from a stop and no excessive slippage when cruising at 35-40 MPH.

olds 307 and 403

Nice real world experience above, 2400 is a nice flash point, you must be making decent torque. My discussion with Hughes were it would stall lower, you will probably be closer to 2000 with your probably 204/214 cam with their 2500 stall. I bet your current stall is something like 1500 flash stall which blows.

kiloman_11

Would I see any difference between the two while highway cruising? Between 70-110mph? It's a non-lockup as well. This is all really helpful