I have a mild build 350 backed by a 700R4 transmission. Normally when in overdrive, the rpms would run around 2200-2400 at 70 to 75 mph. Over the last 6 months the rpms have steadily increased to 3100 at 70 - 75 mph. Is the torque converter going? Is this an issue where the lock up is failing? Or is there an issue with the overdrive gear? In 1st thru 3rd gear, the rpms haven't changed.

 

And your "standard" instrumentation for RPMs would be .... ?

 

Standard instrumentation for rpms would be tachometer verified when speedometer was calibrated by local shop.

 

I have a digital timing light that displays RPM. Use something like this (even an aftermarket gauge) to verify the gauge in the dash. Does it sound like it is reving 500+ RPM higher?

 

And this was, of course, AFTER this symptom appeared, right?

 

sofakingdom, I'm not sure what the hell your problem is with the condensating remarks. The rpm gauge was verified before this issue started and I also have a digital timing light with rpm display.

Morgsie, the engine is definitely running higher rpms in 4th gear. I see it on the tach and can hear that the exhaust note is louder with the higher rpms. After doing some research on my own and talking to a few other people, I'm pretty sure the clutch pack is going out. I plan to tear it down next week and do a complete rebuild. Thanks for responding.

 

Yes 84 it could be starting to slip a little. If it were mine I would also think about a new torque convertor also sense you will have it all apart. Let us know what you find in there, maybe some pictures.

 

New torque convertor is part of the planned rebuild. I'll definitely post the outcome with some pictures of what I find and the rebuild.

 

We will be standing by for updates.