What is the purpose of this bolt in the cover?
Oneal, that's to adjust the tension of the fan belt.
Oneal: It is for the adjusting of the fan belt tension.
Neol,I see by your profile, you have a 26 T so I can see the why on your question, a 26/7 doesn't have that type of belt adjuster on the cover.
However, everything before '26 models did have that tensioner bolt clear back to 1910. Which brings up the cover you showed a picture of. It is a pre-generator front cover. Based upon the shape of the oil filler, from 1915 through 1918, and some non-generator option cars into 1920. Tensioner bolt or not, this cover will not fit a 1926 car without the non-generator side cover for the timing gear.
My 1926 runabout has the same cover with the bolt adjuster in it. I wondered the same thing until I discovered from photos that this was a belt tensioner for earlier models.
Thanks for replying. The picture is not mine. I couldn't load my own photo. The bolt is missing in mine. Just wondering why. Ya'll are the only ones I can ask being no one I know owns a T. Thanks again. Neal
Early '26 production still had the boss on the timing cover - and on my first day production engine (July 27, 1925) it's drilled and threaded just like '25 and earlier.
Here's the little casting to block off the generator when using that cover.