Martin 7.5 head/case torques?

[Mas]

Anybody know the head bolt and case torques for a Martin 7.5 Twist-Shift?

Mas

 

[JB]

Re: Martin 7.5 head/case torques?

Not exactly, Mas, but I have a little chart here to suggest torques for various size screws.

Screw size----------ft.-lbs
#10---------------- 2-3
#12---------------- 3-4
1/4"---------------- 5-7
5/16"---------------10-12
3/8"----------------18-20

Hope that helps.

 

[Mas]

Re: Martin 7.5 head/case torques?

Thanks! To be honest, it's the best thing I've got to go on. The service manual states, and I quote, "tightly and snugly!" Very vague.

Mas

 

[F_R]

Re: Martin 7.5 head/case torques?

Thanks! To be honest, it's the best thing I've got to go on. The service manual states, and I quote, "tightly and snugly!" Very vague.

Mas

Tightly and snugly in this case means as tight as you can reasonably get them with a large screwdriver. Note "reasonably"---meaning don't strip the threads.

 

[Mas]

Re: Martin 7.5 head/case torques?

I guess that's what I'll do. My real concern is the head. There is a multi-part gasket system that I believe can easily fail. I've heard of too many lower pistons seized (rusted rings)...including two of my used power heads on Martin motors. The head has 10 screws/bolts arranged in five rows of two. The manual says to tighten the upper, middle, and lower "tightly," the the two intermediate rows "snugly." It seems there is a great chance of unbalanced torques on the head leading to potential failure.

Maybe I'll practice on my parts motors with a large screwdriver and torque wrench combo and see what values I'm able to achieve.

Mas