289 date code help!!

robbz28

Member
Sep 23, 2009
775
5
19
Epps, LA
Guys I have googled till my googler broke...i have researched date codes and am convinced that my 289 is the original engine out of my 67 mustang, all of the casting numbers on the heads, block, everything points to this, the only code i am having trouble deciphering is the date code stamped on the deck of the block....here it is: 6L4Z yes a Z not a 2....now whats up with that? Everything i have read said that the code reads as such 6 = 66, L= Nov, then the next 2 numbers are supposed to be the date...now my car was built on Nov 16, 1966....this engine being built on november 4 1966 sounds great, but whats with the Z in the date code? All the sites I read lead me to think that if it was built on the 4th then it should have been 6L04, I dont know...help!
 
If it was built on the 4th then the correct date code would be 6L4. Never seen a "Z" included in the date code. Also check the date codes on the heads. Inside ther valve cover, right up next to the cover rail. There was also a thin metal tag affixed to either the carb or intake with the build date and engine info.
 
Well this is strange then, it is clearly a Z, in the proper font and size, i have no reason to think this was added, i know that in some other numbers Z represents the mustang line. I checked the dates on the heads and they are also november 66 heads, smog heads as well. I have a pic i am going to post, i am really confused over this. This is my first ford....anyway, i will load a pic and post it after this post...
 
Hope this works...stangnet keeps throwing me errors when i try to load a pic, had to load it on one of my camaro forums, but anyway here is the pic....the 6 looks like a 5 in the pic, but trust me, its a 6, this pic was a pain in the butt to get to show up...
picture.php
 
Oh yeah...and in response to an earlier post, i do have the intake tag as well and it seems to be the original as well...i would post all of my numbers i have collected, but im at work right now and if they will help anyone with helping me get this engine all straigtened out id be happy to post them when i get the opportunity
 
Ok...i think i may have answered my own question here, i found a site and the Z at the end of the code is the engine inspectors code letter.....so basically whatever ford tech back in the day checked my engine once it was built, stamped the date 6L4 and then added his code Z to the end of it...this sound right to anyone? Here is the link to where i found this info..scroll about halfway down to Used on: Engine Block...

Ford Date Codes
 
that pic above isnt my block....thats runawayabc123's....mine does have a date of nov 3 1966, i looked up the heads today too, they were also cast on nov 3, then the engine build date of 11/4/66, i believe thats all the original componants, also have the intake tag, but i dont have it handy to list what was on it...