Torque converter problem?
 

Took my '74 Fury for a ride after a lot of issues with my 727 to A518 swap and noticed that throttle response is not right, the car feels like a dog, the shifting between gears is really nice but on every stop light noticed a weird noise coming from the front of tranny, something like pressure coming out from somewhere (like pressurized steam) and this only happens with tranny in a different position than Parking (R,N,D,2,1,) but in reverse this noise changes for a different one like a hydraulic noise. While driving at steady speeds I can hear a "clunking" noise like something were loose, I though this was a driveshaft issue but I think isn't because the noise stays even at very low speeds so isn't consistent with car speed

I already told that the car feels like a completly dog, BUT! If I manually engage the lockup in 3rd and 4th gear, man! the car completly wakes up, throttle response is A LOT better and even the noise that I though was coming from driveshaft decreases

I think all this points to a torque converter problem, I had to replace the tranny stock converter (was destroyed) with a rebuild unit so I think this increases the chance of a problem

I'm not sure If I should discard a tranny issue because it shifts right, I don't hear noises coming from it and also I don't notice any slippage with the lockup engaged

Sure its not a front pump noise?

I'm not sure, I had to take apart the pump to change front seal and input shaft bushing but didn't noticed any strange while assembling it again

But, can the front pump noise explain the lack of acceleration without the lockup engaged?

I dont think Ill get off topic on the power issue. I will assume that this was a good runner engine before the trans issue....

I think you have a pump issue or a valve body issue and maybe possibly some miss matched parts..

I would suggest that you talk to the folks at PATC.... :) https://transmissioncenter.net//?swo...=transmissions

I'm not sure if this is an engine related problem, I know I'm running a bit lean but everything seems to be working fine (easy cold and hot start, not hesitation while accelerating, and passed smoke test 4 days ago without problems)

I suspect is a torque converter issue because the slipping feeling goes away as soon as the lockup engages and then I feel a huge different in performance, throttle response, basically it feels like a complete different car

if maybe the problem is the pump instead the torque converter, shouldn't I be experiencing other issues like erratic shifting, random slippage, gears not working? can a pressure test discard a problem in the pump?