I'm am torn in using spacers since my dash pad shows very very little distortion (thanks Jeff, in case i do decide to make spacers!!). However, its hard for me to make out the screw numbers in your diagram ie. 52735-523?? Would I look into this from AMK, Ford??
The best I can determine is the part number shown on the drawing is 52735-S13, 10-12X5/8 Pan Head, Phillips drive, chrome plated. The "tip" type usually requires a pre-drilled hole. They are the screws used WITHOUT spacers. With spacers, the same diameter, head type and drive type should be the considered. That leaves length, the pitch will be either 12 or 16 threads per inch, the current standards. The spacer will need to be at least 0.187 inch inside diameter, but -
- Someone else measured his tubes/spacers as 11/16" L, 1/2" OD, 1/16" wall
I question the "11/16" inch length on the basis that I do not know the thickness of the dash pad in the mounting area.
THAT"S NOT A CRITICISM, I DO NOT KNOW.
The 1/2 inch diameter seems to be appropriate (and reasonable), there needs to be enough mounting surface area to keep the tach from "wobbling" on the dash.
If I were to fabricate spacers, I would use a section of 1/4 inch ID steel pipe and cut two spacers to a length about 1/8 inch less than the thickness of the dash pad. You do want a slight depression.
For screw length, a minimum of 1 1/4 inch would be my first choice. I don't think that a 1.0 inch length is long enough.
Unfortunately, Ford did not use a standard tip 10-12X1 1/4 inch pan head (or 10-16X1 1/4 either). AMK does not list those either. That's leaves you right where you started.
Merry Christmas anyway.
Jim