727 experts, is this factory?

This a hole drilled into the side of the valve body casting where the high pressure spring goes. 1969 valve body with the plastic comb and no part throttle kickdown. I don't recall seeing that before and was wondering if it is factory

A better picture would help. That one looks like you took it with a potato.

HEY!!!!!

Thats pics nuts though, seriously who can tell anything from that...... snap a good one.

But its look like a hole in a casting that might not be helping you.

LMAO !!!!!! what kind of Potato ?????

Hey guys, I knew I'd get crap for the picture!! That's the only way I could get the picture under the file size limitation that Moparts has on the pictures!

And after 28 1/2 google searches on how to change the picture/file size, I gave up, guess I'm too old for this high-tech crap!

I think you too close to the part. Back away a bit.

Thanks! That pic reminded me that I have an eye Dr. appointment!

Try this picture

That is not factory, some shift kits did that mod for increased pressure relief, it also included a different spring for that. Pretty sure transgo did that in the 70s. It should be an 1/8" hole, that one looks bigger.

Yeah, that's a Transgo TF-2 mod; should have a white spring on the check ball.

Thanks guys, I appreciate it!!!

stupid question-
did that hole have to have a drain back valve was it plugged ?

On the pre-'66 there was a stamped steel pump check valve over that pocket, on the '69-later there is a high pressure relief valve (ball) in the pocket. The factory relief channel is fairly small and won't flow much volume so the drilled hole is added to provide more flow.

Thanks John!, so that hole just adds more pressure all the time (line pressure?) or just during shifts? Just trying to understand a very (to me) complicated system!

It is the relief of pressure, not higher pressure. When pump pressure too high the ball is moved off the port and the fluid flows out the channel and that hole. So it makes sure that pressure is relieved.

The factory says the relief ball is to relieve pressure when Reverse is engaged and the fluid is cold. In Reverse, the line pressure increases by a factor of about three, so line pressure can exceed 300 psi under those circumstances and that much pressure can bust parts...especially the rear band and its linkage.

Makes sense now, reverse is always a hard hit! Thanks guys, I appreciate it!!