68 Intake manifold oddity
 

I was digging through some of my old stuff recently and pulled out a 1968 GTO intake manifold. I checked the p/n, and it is missing a digit. The p/n should be 9790140, but the 4 is totally missing. It's not badly corroded, it's just plain missing.

I've seen a few heads over the years where the digit for the year was missing from the cast date, but I think this is the first time I've seen a totally missing digit in a p/n.

Is this common?

https://dl.dropboxusercontent.com/u/...O_intake_3.jpg

I see a faint 4 but yah it looks rubbed down for sure

Theres a couple of reasons for that missing or light 4. 1 the sand cast could be getting old & it's time for a new mold. 2 the guy who dumped or pulled the intake out of the mold put his finger on that spot on mould so the next one through would have the 4 missing or light. 3 when the intake fell into the cooling pit it hit another intake or a hard piece of sand & it rubbed the 3 down while it was hot. There are a lot of variables to know exactly why ..

I think you're seeing a little bit of smudging of the rust/grease where I rubbed it with my finger when I was trying to determine if the 4 was missing entirely. I sprayed my intakes with white lithium grease to keep them from rusting because I stored them in an old barn.

Mike

Not common Mike in fact it's the first one I've seen.

I've seen missing numbers before on some 1971 parts. I have a single #96 head where the year digit was missing from the cast date.

I believe I have an explanation for why you would see missing numbers in a cast date. Since the cast date changes daily, the four digits of the cast date were probably put into the tooling as inserts so the casting facility could easily change the date.

That explanation doesn't hold for the intake. I would think the p/n would be a permanent part of the tool since it shouldn't change. The p/n would only be an insert if you expected it to change, so I would expect the entire number to be an insert in that case.

Mike