Are 1275cc cylinder heads date coded?

[Vespa]

I just found out today that MGB cylinder heads have the date of manufacture (or, at least the date of casting) on them, and I was wondering if 1275cc heads have the same thing?

- Paul B.

 

[Spridget64SC]

Not that I am aware of after 35+ years of working on the A-Series. Some of the castings for the 1275 heads have numeric and alpha codes that may be a date code for that specific foundry. But, these castings don't come up frequently enough to discern anything meaningful. Usually see something like '07B' or '04D' inside the valve cover.

For general information, a 12G940 non-smog head would have used on 1275s sent to the USA in 1967. The 12G1316 smog head was used on the 1275 USA 1275s from 1968 to 1974. These smog heads came in two varieties. The early ones (1968-1971) had the better flowing exhaust ports. The later ones (1972-1974) have the restricted exhaust ports with the cast iron bosses aroung the exhaust valve guide. HTH - Mike Miller

 

[dklawson]

You can also order later 12G940 heads from the U.K. in both "small" and "large" valve configurations. They were used on the 1275 (including A+) for many years. I currently have a big valve 12G940 head on the Mini as its original AEG163 head had deeply recessed valves when it was time to rebuild the engine. Some of the later 12G940s are distinguished by a "relieved", rough cast area around the T-stat housing as opposed to the continuously flat surface found on a lot of the earlier heads. I have not seen date codes on any of the heads I have seen either.

 

[Hap Waldrop]

You can also order later 12G940 heads from the U.K. in both "small" and "large" valve configurations. They were used on the 1275 (including A+) for many years. I currently have a big valve 12G940 head on the Mini as its original AEG163 head had deeply recessed valves when it was time to rebuild the engine. Some of the later 12G940s are distinguished by a "relieved", rough cast area around the T-stat housing as opposed to the continuously flat surface found on a lot of the earlier heads. I have not seen date codes on any of the heads I have seen either.

Those late model Mini 12G940 heads with the bigger intake valves are notorious to crack in between the valve seats. I've seen it numerous times.

 

[dklawson]

I remember you saying that before Hap. The cracking between seats is certainly well documented for the earlier big valve head, AEG163. Do you think the cracking you have seen is more common on a 12G940 on a race engine than a street engine?

 

[dklawson]

Update.
I posted a thread on a U.K. board I frequent asking about the reliability of the big-valve 12G940 castings. I received replies from several racers and a couple of engine builders including A.C. Dodd.

Their unanimous reply was that the factory big valve head is OK with its 35.7mm intake and 29.4mm exhaust valves. However, they also said that the heads do frequenly crack when larger valves are fitted. In particular they mentioned that it is not uncommon for builders such as Slark to fit 37mm intakes and 31mm exhausts which do commony have cracking problems. Dodd's comments were that any valve larger than the stock factory size puts the head at risk.

I am not disputing what Hap has seen but I wonder (based on the comments from the U.K.) if the cracked 12G940 heads he has seen have had larger valves than what the factory installed.