Help Identifying a tag
 

I've been working on my 1966 GMC 305E that has some bent push rods due to stuck valves - that's a different thread.

During the top end tear down I found a metal tag wired to the exhaust bolt keeper it reads "060" or "090". The truck has under 13,000 miles on the odometer and came from a low use municipal setting.

Any ideas?

Re: Help Identifying a tag
 

I was thinking maybe engines been rebuilt and was bored .060

Re: Help Identifying a tag
 

No .060 over pistons available that I know of for a 305.

Re: Help Identifying a tag
 

I agree on doubting a rebuild. Everything I found from head gaskets to valves was stamped GMC.

I was wondering about a special order tag. Being a fire support truck, it has double belt pulleys, dual batteries, etc.

One thing is clear it was "build or unit 2591" there are grease pencil marks throughout the truck

Re: Help Identifying a tag
 

Egge shows .060 piston rings in stock for the 305 GMC V6.....so someone either did or still does make them. Your far more a GMC V6 guy than me though TJ. I don't even know how far a 305 can be over bored personally....but as thick as the walls are I would imagine you'd have room.

Odd tag either way...and the mystery continues.

Re: Help Identifying a tag
 

I had meant to mic the bore, but it slipped my mind. Heads are back on now.
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Re: Help Identifying a tag
 

Did it look like an recent work had been done when you had the heads off?

Re: Help Identifying a tag
 

Everything I saw looked original. Head gaskets stamped "GMC", valves stamped "GMC", etc.... There was none of that damn silicone gasket material everyone loves. The head and deck surfaces had no swirl or scrape marks (till I started)
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