A2Mechanic

I just finished rebuilding my 455 for the 68 Delta 88 and I also had the TH400 rebuilt. My question is how do handle the start-up Transmission fill and engine break-in all at the same time. I believe I can only add 4-5 qts to start with in the transmission because it will over flow if I add all 10 at once. My cam is a comp cam xe268 flat tappet.

I also wanted to thank everyone for all the excellent information here that helped me every step of the way on this restoration.

Fun71

Last time I rebuilt a transmission we put a lot of fluid into the converter before we installed it, then added fluid through the dipstick tube. After firing it up, I think it took only a couple more quarts of fluid.

joe_padavano

I'm about to go through exactly this issue with the 455 and TH400 for my 67 Delta. I have an engine run stand. In your case, simply do not bolt the torque converter to the flexplate. Ensure the converter is pushed all the way back into the bellhousing so you have as much clearance as possible between the converter and flexplate. You may want to restrain the converter in this position somehow to ensure it doesn't walk forward with the engine running. Now break in the engine first, then bolt the converter to the flexplate and break in the trans.

A2Mechanic

Perfect, thank you guys. I think I will leave the converter unmounted as I am installing both engine and trans together and at that angle even with a cap in the end I most likely would have a fluid dump, lol. I will report what I used to hold the converter back. This entire B-Body build has been improvise, adapt and overcome, and I wouldn't have it any other way!

A2Mechanic

Solution to hold converter back during engine break-in.

OLDSter Ralph

That looks like it could work.

joe_padavano

X2. Nice work.

A2Mechanic

My converter wont slide out to meet the flexplate. I'm certain that I have the flexplate on right as I looked at the witness marks and can see them now were the old converter bolted up. My converter is the hughes 2500 for BPO. The distance between bosses and flexplate is about 1/2".

I figured it out. Pulled the trans down and although the converter was back all the way in the trans-while breaking in engine- the 'snout' was hitting the crankshaft and it knurled it enough to prevent the converter from seating into the crank and the bosses from seating on the flexplate. I was able to polish the snout and test fit it in the crank and in the trans and it appears all is well. There is no evidence that the pump or converter spun and every time I checked it during break-in (with a mirror) it was stationary.

rustyroger

I'm curious, I know why a rebuilt engine needs breaking in, but why would a transmission need breaking in?.
When I had my TH460 rebuilt I simply filled it with about 5 liters of fluid, and added a liter less than the total required as it was running. Then I selected all the positions on the shifter, checking it loaded/unloaded properly. Then I checked it was up to the full cold mark took it for a ten mile drive and made sure it was up to the full hot mark.


Roger.

joe_padavano

Not really "breaking in" in the same way as the engine, but the trans does need to be operated at slow RPMs through all the gears without load to get the oil flowing to all the bearings and bushings. Idling the engine while you run through the gears in the trans is not conducive to camshaft longevity the first time you fire a brand new motor, and running 2000 RPM for 20 min to break in the cam is not conducive to longevity the first time you spin a brand new trans.

A2Mechanic

The car is done (for now) runs great, shifts great. I'm to old to install a th400 on the ground, phew!! Thank you again.

BillK

I have never had a problem with an automatic trans during engine break in. I usually put 5 or 6 qts in and let it rip. If you are worried about it have someone add some more fluid once you get the engine started and running. You really should have at least two people there during the procedure anyway.