75 maverick 250ci transmition issue

I have been working on my 1975 ford maverick 4 door with the 250ci inline 6 and I got it all back together and went for a test drive. It runs great it just won't get up to speed. Around 35 it seems to just struggle seems like it's just not shifting at that point. It ran fine before. Any thoughts?

 

Is the vacuum modulator valve hooked up? Check the vacuum line on the trans and up on the engine.

 

how long did it sit?

 

What all did you do to it? If it ran fine before, maybe something you did is causing this. Greasemonkey has a good starting point.

 

Ok I'm at work now I'll check when I get home

 

2 months

 

I changed the head gasket, timing chain and gears, and switched to open air intake

 

I would check the modulator first. I would also check the timing and verify the spark plug wires are where they go. You should be GTG after that.

 

Is the firing order clockwise or counter clockwise for the 75 online 250ci ?

 

Clockwise