What year

[D.Yoder]

Were the round & oval hole

covers used?

[RajoRacer]

I believe the "round" hole cover to be a modified one - the oval hole would have been used through production with the solid cover being the exception for the Vaporizer carburetor.

[DanTreace]

One-piece valve chamber covers:

Round hole 1921-1923

Oval hole 1924-1927

No hole used for Vaporizer carb in 1927.

[D.Yoder]

Thanks! Dan

[DanTreace]

Dean, you're welcome

Good view of it from Ford Service, photos in this manual are from a high radiator touring, 1924.

[John kuehn]

That’s a detail I hadn’t noticed! Not that I am really knowledgeable about details but I can understand having a little more ‘wiggle room’ for the gas control rod. I have a 21 Touring and a 19 Roadster and they have the later oval shaped hole valve covers. I had a few engine parts already so that’s why I used them. It’s important to a purist and that’s OK but it is a practical improvement. I’ll leave mine as is.

[RajoRacer]

Where did you locate the information regarding the round hole cover particular to those years, Dan ?

[DanTreace]

Bruce's work from C-D Encyclopedia:

Beginning with 5,812,609 (April 3, 1922) all engines used the single door. [The book states first one piece door Nov 1 ,1921] So maybe many engines in this time had the twin doors. This first design one-piece valve door was round hole.

During 1927 the hole between the center cylinders was closed. Since all cars used the Vaporizer type carburetor, the throttle rod passed over the engine instead of through it.

The dates for the oval hole cover is from examples have seen, later 1924 models have the oval hole valve door, my guess was done along with many little changes to other parts at that time, like the large funnel oil pipe, and hogshead with raised lip inside the upper housing to flip oil over the bands. These later '24 and the '25 had lots of similar changes. The low radiator T's from '22 to '23 mostly have the same features.

Now Gail Rodda shows the valve cover doors in his publication Parts Identification Guide Vol. 2 page 46, and states first one piece door had round hole, and came out in 1921. And he states the round hole was used as 'late as 1925', then states the oblong hole is later, but no reference on what date used.

However his use date for first cover one piece cover is similar to Bruce's research ref. And I think his late as 1925[/i] for the round hole cover may be off, from the many examples of late 1924 and 1925 originals I have observed, these have the oval hole cover.

And for the fact that Ford Service book, clearly shows the oval or oblong hole one-piece valve cover pictured, and that book is 1924.

If anyone has actual use date from Change Order cards or blueprint on the one-piece cover 3110B (Fac. No. 656B), and shows a date of oblong hole change, that is later than 1924, that would change these dates for me.

[RajoRacer]

Thanks Dan !