If you’re rolling along at 70 and give it a little pedal does it accelerate crisply or just ‘flare’? Can you borrow a tach from someone (or even buy a cheap one at the parts store?) I can’t imagine what you’re describing not being a much bigger problem with bad symptoms (unless the tach is wrong). A trans that’s slipping to the tune of 1200-1400rpm at cruise would be heating up, acting weird, etc. I’m sorry I don’t have an answer but can’t wait to hear what solves it. Patrick
I would say closer to flare. Very sluggishly accelerates, RPMs seem to increase more than I would think for the speed gained. The one piece of the puzzle I don’t have is an oil temp. Tach is good, it’s been running on a different car for a few years and just switched it to this car. Going to verify the tach signal is correct this weekend. Fresh wiring and HEI last year so I’m doubtful it’s that.
My question is have you owned this car from new, and do you know it's complete history? If not, you really can't say it is all original, it may not be. Lot's of things get changed in a car over 50 years old. Do the numbers match? Sounds to me like a torque converter problem. Either the wrong converter was installed in the past, or this one is bad. Might also be a stator problem inside the converter. The stator has a one way clutch that keeps it from rotating as long as the impeller (front half)), and the turbine (rear half) are rotating at different speeds. The converter multiplies torque up to the point of coupling. (both halves operating at close to the same speed) At converter coupling, the stator freewheels with the turbine. There are 2 types of stator failure, constantly stuck, or constantly freewheeling. If the vehicle accelerates poorly to about 30-40 MPH, but pulls well at higher speeds, suspect a stator that is freewheeling at all speeds and has no torque multiplication. The opposite problem is a constantly stuck stator. The vehicle has good acceleration up to a point, but top speed is limited to 40-65 MPH, the engine runs very hot, and gas mileage is bad. Of course the transmission may be slipping badly as well, but I would expect the fluid to be burned.
While you are correct I have not owned this car since new I have for the last 12 years and have had the transmission/torque converter/rear end out. The cases are all numbers matching. The original post was referring to a question of rpm as this is the first year I've had a tach in the car. There are other symptoms the car has that point to a transmission failure. I believe you are correct with the failed stator along with being sluggish there is a rattle that lines up with stator load. The fluid was changed 2 years ago and isn't driven too often. After lowering the pan there is some metal shavings contaminating the oil. Assuming the converter and transmission are failing and slipping to add up to the 1k slip at this point. So time to pull it and make her run well. Thanks for the help!
I actually have an extra 700r4 i'm going to put in it. Planning on locking it in 3rd until I can swap the rear gear.
