727 Trans Slow to Shift at WOT

Getting ready for fun at the Local Drag Strip and I have a concern. Last time I had the car out, and many times before that, I would bang my B&M shifter from 1rst 2nd, then 2nd to third and there was always a slight 1/2 - 1 second second delay before going into the next gear. The trans doesn't slip and the shifts are strong and positive. I have my shift light set for 6000 RPMs but by the time the trans goes into the next gear, the RPM is about 6100. Linkage appears to be set up correctly. The trans was rebuilt about 10 years ago with a cheetah reverse manual vale body and aside from the late shifts, there are no other trans issues. Any ideas?

You have to set the shift light early. If its a stock valve body casting the amount of RPM gain increases as the car gets quicker. The feed to the front servo has a long path. You'll notice the 2/3 will have less RPM gain. To shift at 6900 my 1/2 is set at 6300. The 2/3 is set at 6450. This is in a 9.1X ET car.
Doug

So Doug, this is typical then? I have a good set of pills so I can adjust as needed.

Have you adjusted the front band lately?
If not do that next and see if that helps the 2/3 shift
The other thing to check is the shifter linkage adjustment, you should be able to put the shifter in 2nd gear and remove the shift rod retainer and push the rod end up out of the shift arm from the tranny and see no movement on the arm, if that is good check 3rd gear engagement next. If either one move adjust the linkage so it does not move at all when putting the shift rod end into the shift arm hole in all 3 gears, reverse and neutral
I've had and race with many 727 T/A Cheetah reverse manual valve bodies in both the early cable shifters cars and the 1966 and later tranny, all of them shifted quickly clean when adjusted properly

Will do

In my experience, yes
Doug

A 1/2 to 1 second delay and the engine only gains 100 rpm?

I even had the 2nd gear servo passageways on the valve body made larger, (Turbo Action Chettah). The rpm spread is better now for sure. But it still takes a given amount of time to complete the shift. The quicker the car, the more rpm lag it will have. This is checked using a play back tach. Also why many cars will go quicker with an earlier 1/2 shift point, they're being over revved. Mine runs a red hard band, aluminum drum, lightened sun shell, 3.8 lever. Same band and drum for well over 500 passes. Both looked new at last inspection.
Doug

It would reason to me to confirm the position of the manual valve, relative to the passages in the body, when the detent is in the 2nd gear position, and again when in the 3rd gear position. There's a bendable arm on the detent that engages the manual valve to correctly position the manual valve. You may also want to check the valve body for flatness. You may have an internal leak thus delaying the complete engagement of the high clutch.

Removing a few return spring in the direct clutch may help as well.

My trans is taking about 400 rpm to shift... was a lot more until Pro Trans did whatever they did. Playing with the air shifter my ideal 1-2 shift is at 1.4 sec after releasing the trans brake. I try to do that by hand and it’s been from 1.7 to 1.9 which raises the engine rpm considerably (7100 shift point to a 7850). Like Doug said.... the faster your combo the faster things happen. I think a lot of people would be surprised if they saw actual data of their pass.
Our high 10 combo takes 2.3 secs from t brake release until the desired 6800rpm is achieved for the 1-2 shift. Of course a lot of that is I’m using the same converter for our low 9 W8 mill so it drags the rpm line flat for about 1 sec after tbrake release before climbing significantly. 1000 rpm stall between the 2 engines.

At 6500 RPMs at WOT under full load, yeah about 1/2 plus second to go from 6500 to 6600.