I have a double hump head with the date code of W243.
I thought you took A for January, B for February and so on. Apparantly I don't know.. The head is a #3991492 which came off my '70 Z but was not original to the car. Does anyone know how to read this date and what the head came off of ??
Thanks,
Steve

Other than being pretty sure it's a 1973 casting which should make it a service replacement head, I'm not sure of the month.

I'll check it very closely tomorrow and see if I got the W part right.
Steve

3991492 lists on Mortec as 1970 and up LT1, AND over the counter CamelHump 64cc straight or angle plug (aka service replacement head like Rust said) Your right in the date code should be [Month:day of month:year of the decade]. I'm going to assume the W is somehow associated with the over the counter replacement / service head as Doug said, but what the "W" really is??? that's just a WAG. The fact that the engine is 'not original to th car' you apparently not looking to verify a numbers matching car, so the casting date is probably not of any real importance. It's a 492 head which is a very decent head for the era. I don't know if by 73 they had started putting hardened seats in heads yet (for unleaded fuels) something some of the more knowlegable machinist here can tell you.

"W" is odd, since we don't cast date codes past "M" We only cast letters A-M, except the letter "I". "M" being December.

That said... If it's the date stamp on the rocker valley of the head
W243
"W" is.....
"24" is the 24th of the month
"3" is the year code.. In this case, most likely 1973

I didn't get to my barn/shop today to check to see if the W is right. Will get down there tomorrow. I got this head (492) when the machine shop I sent my original (186) head to cut too deep while doing a valve job and installing hardened seats. He replaced my head with this one. The engine in my car is the original 350 (CTB) block. I had some other problems with the block and pulled it again about 6 months later and found that the same machine shop had cut through the water jacket area on the other head too. I bought some replacement heads from the new machine shop and had them machined and they are still on my car. I now have three double hump heads two ..186 and the one ..492. I was going to see if the heads could be repaired. I can't see throwing them away. I have a friend that said they can probably be repaired but I don't know if that would be cost effective or no..
Anyway, thanks for the replies and I'll check on the W tomorrow..
Steve