MTFCA Forum

What is the spacing between the insulators on a wooden firewall?
That is the spacing between each of the 8 ceramics that go through the fire wall?
I have measured 2 coil boxes and have some variation in the range of 1 or 2 32nds.

Thanks, Adrian

Like other Model T components they weren’t always made to exact measurements. They were generally in the correct position but not exact.
Machined parts were a different story but body parts and etc not quite so close.
My opinion after buying NOS parts and finding out they weren’t as accurate all the time as you might think. My opinion of course.

Does anyone have a diagram with spacings marked out? I found one, but without dimensions included.
Thanks
Adrian

The holes in a metal fire wall are about 7/8 inches diameter and about 2-3/8 inches apart in the row, I think wood would be the same. That allows quite a bit of room where the insulators are located, not a glove fit. Working from the center of the firewall out, drill the holes so your insulators are more or less centered to the hole. That give room for slightly different spacing if different coil box is used.

I just built a firewall for my 1915 Touting car. What I laid out was evenly spaced holes for the coil box insulators to go through. i laid the coil box on my marked up firewall, centering it. 2 holes lined up, the rest were off. I ended up measuring each coil box brass bolt spacing and remarked the firewall then verified the hole center line was correct by placing the coil box on it before drilling. I used a 1" Forstner bit with wood backing on a drill press to get the holes straight and prevent wood chipping for the coil box insulator holes. I don't have an original firewall and the one I had used 1" holes.

Only have this partial print, 1917 firewall. Shows at least the hole space distance between a pair, might help. This was posted on the forum a while back.

Thanks guys, i laid a box wood back on the firewall and went from there. Worked ok but my niggly back of mind says 'it might be wrong'