Shifting Question - TH400
 

Hey everyone, I have a recently new to me 68 GTO that I bought and have been tinkering with now trying to get it right. The Engine is a 400 bored 0.030" over and sounds to be running strong attached to a TH400 his/hers hurst shifter.

My problem is when I am at WOT the shifts are very slow, like the car takes a few seconds to figure out what gear to go into (RPM according to hood tach is around 4-4500 when it starts thinking about shifting). Normal driving it shifts fine. Where do I start trying to troubleshoot this? When it does shift it shifts hard. I believe there is an 1800 stall in there. What is some other information that you all need to help me figure this out.

I have some other issues that I need to address as far as timing and carb setup, but those will be a different thread.

I'd start with a gauge and monitor your pressures. Sounds like a leak.

Where should I monitor from and what would I be looking for? I am pretty sure I can hear a vacuum leak under the hood, but havent been able to pintpoint it yet.

Fix your vacuum leak.....you have poor vacuum to the vacuum modulator on the right side
of the transmission. That could be causing your problem.