I would like to know the exact width and height of the wood firewall used from 1917-1922 ?
Thanks in advance
Exact might be only possible with ref. on original Ford drawings of the year/month your Ford was built, and at what point you measure. Firewall changes were many during those years, and varied if for non-starter car too.
Can only give rough very approximate dimensions, from my repro dash, 19 3/4" tall, and 24 3/8" wide, measured at the center for height, and measured for width across the center line of the steering column hole.
Repro wood low dash
Typical metal low dash
Were the firewall dimensions the same for the model T cars and trucks during 1917-1922?
No. When the starter was added in 1919 the inner radius at the bottom was trimmed to allow clearance for the starter thus both of the pictured dashes are from the starter era and the 17-early 1919 were slightly different. There are also some small changes in the dashes that made it kinda unusual for the dash to have had zero changes from the start of a model year until the end of that same year. Most are small enough to be ignored by those making repro dashes or can be added later sometimes.