Was recomended to do this by a local transmission builder. Been reading and havent came up with a good answer. This is a stock 4l60 rebuild in a 2007 gmc 4x4, Trans go kit, pinless accumulator, .5000 boost valve, and stock replacement converter.

 

Do you understand what you are doing hydraulically when you do this modification?

 

I don't believe any sponsor or pro builder here blocks that exhaust port.
I would expect it to cause problems with the 3-2 downshift.
It might be OK for a pure drag strip car that never has even part-throttle downshifts, but not a street car.
I'll defer to pros like PBA, Clinebarger and Jake, but I would consider finding a different builder, as this is probably only one of many undesirable "hacks" that would be performed.

Before making mods, one should always understand why GM built something the way they did. Rarely do you disable something that cost extra to implement. Sometimes GM's reason was to save money or make a soft-shifting trans for Ms Daisy, but that is not the case here.

 

Perhaps PBA, with 30+ years of performance building experience and thousands of customers, will post his reasons here, but in his post #34 of this thread:

https://ls1tech.com/forums/automatic...-thread-2.html #34

he writes:

"Rarely does the 3rd accumulator checkball capsule present a problem. Never install a solid plug here. Always use the capsule."

 

I have never replaced the 3rd accumulator capsule with a plug on a 4L60E.
Just check for leaks....If leaking....Take a Drift & lightly tap the check ball a few times, This should fix the leak.