When did the change from 2 small valve covers to one long cover happen? The catalogs indicate either style for 1921 but my 21 Huckster has 2 small ones So I am guessing sometime in 1921. Can anyone verify this please, early, late, middle?? Thanks
The Encyclopedia says the engineering change for the single valve cover was issued very late in 1921:
10-18-21 T400D1 New design (one valve cover) to be run at a rate of 100 per day
Thanks Mark !
That sounds right for the engineering change. But I think the crossover time when both old and newer patterns and molds were being used was unusually long. The matter is complicated by the fact that replacement blocks could have been changed at any time, and been either newer or older (having been on the shelf for a few years) than the engine block being replaced. (I have one with a serial number earlier than the casting date).
I have seen several of the single long valve cover on blocks of 1921. I have also seen the two short valve covers on blocks from early 1923. I figure that the two styles must have been used for at least about a year and a half. However, some of that empirical evidence could be the result of serial number changes. Late 1921 could likely be either style, and certainly the two cover blocks were still being used all the year.
Drive carefully, and enjoy, W2
I have a serial number which dates my block to early 1919. It has the single long valve cover.
The change over time was unusually long, probably to avoid scrapping patterns and molds before they were worn out - a lot of them were used at the same time for casting. The encyclopedia states the change started November 1, 1921: http://www.mtfca.com/encyclo/doc21.htm
and by April 3, 1922 all production were one piece valve door engines: http://www.mtfca.com/encyclo/doc22.htm
The casting dates were also gone in the US (as far as I know) with the last two door engines.
My 22 T with original engine has the 2 piece valve covers and the block has the stamping date of 2/22/22. Also has the unique one piece front spindles that were made in 22 for a short period.
John there were no blocks made before the date posted above that would have had the single door valve cover. Ether you have the wrong door or a replacement block.