I've been wondering about something for sometime. Before I fire up a rebuilt engine I prelube it with a drill until I hear no more air in the system. What about the tranny? Should it also be primed before startup? I have a fresh rebuilt 727 and am curious about it's innards before the fluid is all thru the system and converter.
Not sure about a torqueflight however I filled the convertor for my 700R before attaching the transmission to the SBC in my '35. I then filled the transmission before I started the engine and wound it over to pump fluid through everything before I actually tried to start the engine. It purged the system of air and put fluid in the coolant lines and where it needed to be. Once the engine started I checked the transmission fluid level and only had to top it up. I wouldn't run it dry under any circumstances. If there is no fluid in the convertor now I'm not sure what your next step is, sounds like it may take longer to purge the system.
If 727s sit for a while I read they drain out of the converter and running in neutral not park allows the pump to refil the converter when started.
Put a quart in the convertor and then install it into the transmission, making sure it is seated all the way in. To keep the convertor from slipping forward and becoming disengaged from the front pump, bolt a small combination wrench into one of the splash sheild holes so it acts as a "stop", pressing against the convertor to keep it in place. Bolt the trans to the bellhousing area and you can now remove the combination wrench and pull the convertor slightly forward to mate with the flexplate. Put 5 more quarts of fluid in the pan, and then start the motor and let it run for about 30 seconds. Check the dipstick and the fluid level should have gone down. Add a couple more quarts and start it again for 30 seconds. Check the fluid level and add fluid to bring it to the FULL mark. Start the engine again for 30 seconds and check the dipstick again, keep adding fluid until it remains at the FULL mark on the stick. The 727 usually holds about 8.5 to 9.5 quarts total. Don
Bill, of course my post will get a bunch of naysayers, the " poke an hope " mechanics slapping shit together their whole lives, but if you want the advice given to me by the head of the company who does our racing automatics here goes. After getting things warmed up to temp, with the engine idling, hold your foot firmly down on the stop pedal. Now SLOWLY move the shift lever through all the gear positions stopping and pausing in each one and counting 1-one thousand, to 3 one thousand in each position. Do this twice all the way from Park to low or first gear, back to park, and repeat. Now check your fluid and add or subtract to the correct level required. All the best.
In all the automatic transmissions I knew of, oil supply to the converter happens after the trans itself has sufficient oil pressure. So, starting with a partially filled converter isn't as bad as it sounds. The shifting through the gears procedure that Traditions Racing described will make a small difference in the dipstick reading. I worked for the engineering garage of a trans manufacturer for a while. That routine was standard required practice for a newly installed trans.
I ask this question because I put a 727 behind my Desoto hemi to get the cam broke in and ran it for about 20 minutes. The fluid level never went down the stick as though never pumped up. I put alot of fluid in the torque converter before I fired it and filled it to full on the stick. It came from a guy's pro street Cuda. Said he wanted to go back to the stock 4-speed. Am wondering now if I bought a pig in a poke.
As mentioned earlier, the Torqueflight doesn't supply hydraulic pressure in park, it needs to be in neutral or, obviously, any of the drive positions. If you started it and didn't come out of park, the level is not likely to change.
I've never had problems on first start up with a 727 in park and the drive shaft installed. If you're worried, shift the trans into neutral soon after starting the engine for about 30 seconds, then back to park and you should be good to go. You'll probably hear the engine rpm's drop a bit when the pump in the trans primes and starts pushing fluid through the system. Two things - As soon as you start picking up fluid the level in the pan will drop fast and you'll need to stop and add fluid. The second is MAKE SURE the wheels are off the ground because if you miss neutral you'll have the car running down the road, through the garage wall, or worse...
It is always a good idea, with a torquflite, to to start the car in "N"uetral for a few seconds. Also, fluid must be checked in "N"uetral.