1955 FLH cyl hd PN's and date codes help

[felthamw]

Sometimes, it is just best to ask someone who just might have the answer ..... I didn't have any luck using the forum's search function.

I was out in the garage this morning and am starting to get ready for Eustis meet. (Yes!!!) I have had a lingering question or two regarding my bikes' cylinder heads. (RECAP: they have 12 bolt d rings, pan covers and D&T holes). This has bothered me for a while and I thought today was good to re-visit this situation and see if I had missed anything. Evidently, I did.

I had also bought a used spare front head on e-bay and wanted to check the numbers. (It turned out to be a FL head with no porting and a '54 cast code)

I got out Palmers book and he says the casting part numbers should be 16704-55 Front and 16705-55 Rear. I have a front head on my bike that is correct. The spare head is also correct. But my rear head is 16706-55.

I never saw that before today. Does anybody out there know anything about this 16706 PN? Maybe a designation that it is ported/polished FLH style? If so, why doesn't the front head have a separate number? According to the book, '56 up PN's went to 16700 and 16701, front and rear respectively so there is no help there.

My other question is in regard to the casting date code. On the rear head it is clearly marked "l 5" which makes the casting date September 1955. The front head(s) casting date codes are not as clearly interpreted. The front head on the bike looks like it has a "5" and then a backwards capital "J". Did they reverse/mirror image the front cylinder casting date code letter and reverse the order? Maybe it too is a "l" with the little cast error but the order reversal? I am stumped.
Any help from you guys is appreciated!

[felthamw]

Update

I found a thread on the Hydra-Glide site that more or less details my same questions regarding the rear head's 16706 - 55 part number. And proof that many more 55's have them too. It was explained as being an error in the Palmer book - but never confirmed.
But I still have questions about the reversed date code on my front head. Could have been an error at the foundry? A Monday perhaps? Or Friday? Anybody else seen the letter and number transposed?
Cheers
Wayne

[bmh]

I think they changed the date codes from a letter-number to a number-number around 1950. I think your code is actually "1 5" for Jan. 55.

[felthamw]

I think that you are absolutely correct, Brian. I have gone back and checked pictures of many heads and they all agree with you, provided that they are later than '50 or so. What threw me was the '48-49 head casting picture and descriptive text on pg 182 of Palmers book. I just assumed, and shouldn't have.
That being the case, my rear head was cast Jan '55 (1 5).
My front head was cast May '51 (5 1) ???? NO! I doubt that. I think that the numbers are transposed. The head part number says 16704 - 55.
That spare front head I bought has a (9 4) cast code making it September '54, which isn't a stretch at all.
But, I am still curious about that transposed cast code number on the front head......
Wayne

[bmh]

That being the case, my rear head was cast Jan '55 (1 5).
My front head was cast May '51 (5 1) ???? NO! I doubt that. I think that the numbers are transposed. The head part number says 16704 - 55.

Could ya post a pic of that date code?

[felthamw]

first time pic post here........

looking at these pictures - is it possible the date code is just upside down?

why I couldn't see that earlier while laying on the floor.......................

[Chris Haynes]

I notice that on some heads there is a letter E near the date code. Just another foundry marking that we will never know the meaning on I guess.

[bmh]

They do both look like Jan 55 to me.