This could be a hot start problem. I have a 65 GTO that had that problem  I ran a heavier wire from the battery to the starter and that solved my problem. I also put a different starter in

Interesting. I'll take another look at those cables, thanks.

Pontiac used two different starters, the standard and a heavy duty starter. Look for the heavy duty starter.

Also consider a heat shield around the starter.

https://www.firebirdcentral.com/1967_1977_Firebird_Starter_Solenoid_Heat_Shield_p/enc-2040.htm

https://www.amazon.com/Compatible-1970-1981-Firebird-Manifold-Solenoid/dp/B06XPQB78D

https://www.thepartsplaceinc.com/product/1969/1969-pontiac-gto-lemans-tempest-heat-shield-starter-solenoid/67064

It cranks fast for me. Maybe I am expecting too much. I had a 1977 SJ with the 403 and that thing started right up every time no matter what. I wonder what is the difference between the 400 and the 403???

Grand Prix 

is this a starter motor not cranking or are you having issues with it taking too long to fire up once cranking ?

Starter is good. It seems to take too long to get started. I had a 1977 SJ 403 that started immediately. The 400 doesn't start the same for some reason.

Does the car still have a quadrajet carburetor....?? Has it been tampered with..?? Does it load up and run really rich when first started...Even if the choke is all the way open...?? Does it continuously run rich even when the engine is warm during normal driving conditions....?? Does it bog down when you open the throttle all the way...?? Is it hard to start when both hot or cold..??

Edited April 12, 20215 yr by TWO LANE BLACK TOP

It is a reman same number as factory. It works well no issues. After warm and sitting for awhile that's when it seems to have some trouble starting. It's getting fuel no doubt about that. My idle is set low. It's around 550 in drive and I'm slowing cranking it up.

Technically a 403 (as was used in later 2nd gen automatic transmission Trans Ams) was an overbored Oldsmobile 350. A 400 was a Pontiac engine. So they are two different engine platforms.

That's why the cylinder walls on the 403 are thin. The 1977 grand prix SJ also came with the 403. I've been turning the idle up just a smige every day. It's been idling low and slow the way I like it. However that extra smige of air could be all it needs to start right up after warm.

Ran it around today. In drive at 550 rpms it's pretty smooth. I replaced the factory carburetor a few months ago because the throttle shaft was worn. It gave me an erratic idle and puked fuel at the accelerator pump even after my backyard reman. I used a metal float though! The new(reman)carb is much cleaner running. The intake is clean all the fuel is being contained and processed correctly. The other issue I have is when in park the idle is a bit erratic. I mean it's not very noticeable accept to the trained eye and ear. It smells like it should. The old carb was worse. Maybe I'll spray some carb cleaner around the shaft to see if it's sucking air there. It seems like an ignition problem because the idle will be pretty smooth then suddenly drop and smooth out again. 

     A lifter used to tap when cold and the book says it's okay if after warm it goes away, and it did. I decided to go back into the distributor and replace the vacuum advance and figured why not just replace all the tune up parts. Did that and started it up with no lifter noise. I learned that thru ignition the lifters get loaded. I guess I had another ignition problem at that time that I accidently corrected. 

9 hours ago, Grandprix723 said:

The other issue I have is when in park the idle is a bit erratic. I mean it's not very noticeable accept to the trained eye and ear.

that to me sounds like a vacuum leak Grandprix.

It does. As much as I hate to admit it. I replaced the trans modulator awhile back. The old one was allowing fluid to run up the line to the carb. Whats cool about that is  at least it kept the intake nice and clean. I thought I found the culprit but to no avail. 

Question is why does it run smooth at idle in gear withe a/c on? Then you put it in park and it's mostly smooth but unsteady.