Mystery non factory engraving on engine.

I noticed this while finishing plugs and coil packs today. '99 C2 An 'R' with possibly '8921' below it?... It also looks like they may have tried another number in between the R & 8921. I'll check it tomorrow when the light is better.

Were those heads by any chance repaired by Hoffman? That is where the factory "pairing number" is for the cover to head matching numbers. There should be the same number on the head (without the "R") Definitely not the factory number, but looks an attempt to "recreate" the factory number.

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Thanks for the info but it just makes it all the more mysterious. I'm the second owner and the previous/original owner kept EVERY receipt since new including the receipt for the purchase deposit he put down 22 years ago today. I went through it all again and there's nothing to indicate the head(s) have ever been off. The car was serviced at the dealer for the first ten years and then at a respected local indie shop. Every receipt is organized chronologically in a three ring binder. The original owner lives four miles away and pre-covid, I would see him at Porsche and BMW events. I definitely will ask him about it but I can't imagine someone that **** would have left out documentation for something that required head removal. I took a couple more shots of the other number and it looks like 'R8921'.

Look for the matching number on the head and see what it looks like. There is definitely a story behind that number, but no telling what that story is. I have a set of metal stamps and have put my initials "SB" or "Skip" on some engines I have built, so if you ever see that........lol

Thanks for the pic Skip. I wasn't scrunching down low enough. Maybe the valve cover was replaced for some reason and they used crude stone tools to try and match the number on the head? What does the R before the number mean?

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My first guess would be "repaired" "rebuilt" remanufactured",, Like with the G96 gear box, anytime the gears are pressed off, it should be marked with an "R" next to the serial number, only 4 "R"s are allowed due to the press fit gets looser each time the gears are pressed off. I can't say I've ever seen the "R" on a cylinder head before though. Most head shops don't do this and I've never installed a "Porsche Remaned head".. The one on the head looks pretty good and could be factory, the one on the cover looks really "iffy"..lol

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My first guess was 'replacement' . But since it looks factory, I wouldn't think they would use the first letter of the English word over the German one. The mystery may get solved because I think this cylinder head is going to be getting some closer scrutiny soon. I suspect that my #2 misfire wasn't the coil pack but rather a stuck lifter.

If you research German handwriting,the “9” sometimes looks somewhat like a “g”. I vote factory’. ‘Adjustment in field as required”

I'm guessing your engine serial number doesn't have the "AT" in it? Check the number on the other head and see what it looks like..may give some more insight.. Usually heads of the same engine will have consecutive numbers.

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I wish I had thought to check the other head before I had everything back together. I stuck an endoscope in there but didn't see any number. And no, my engine isn't a replacement. I did find a ten year old thread where the OP mentions having the 'R' on his head though. https://rennlist.com/forums/996-foru...al-number.html