1952 M135 GMC Inline 6 Hard to Crank Over

[ynoteh]

I have a brand new starter in this M135.
It turns over very easily without the spark plugs in.
It will intermittently turn over quickly and then when it’s about to fire it’s like it hits a brick wall, but the starter powers through it, what could be causing this?
I’ve attached a link to the video I posted to YouTube showing it fire up and then after it dies not being able to get it to start again.
First Start Video

 

[Barrman]

Have you checked the ground from the batteries at the frame connection? Same with the ground strap from the starter if it has one and the ground strap from the engine to the frame.

 

[ynoteh]

Have you checked the ground from the batteries at the frame connection? Same with the ground strap from the starter if it has one and the ground strap from the engine to the frame.

The grounds definitely looks solid, they have the 1/0 cables going directly to the body in the battery box, continuing down to the frame beside the starter and across 4” from the frame to the starter, it’s a continuous path from the battery.
The motor does the near lock up thing when I add fuel to it.
I’ve got a toggle switch for the fuel pump and if I leave that off, eventually the motor turns over easily, like it’s Hydro locking or something when it has fuel going to it.

 

[GopherHill]

Check for too much timing advance just in case.