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I have 67 300 HP engine that has the same casting date and assembly date. From a review of the Tech Board archives, I gather that this is rare but not unheard of, especially if the block was cast on the first shift. Where can I find the shift that the block was cast?
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Re: C2 engine casting shift number
Joe -
The shift marker is indicated on the date tag by the screws holding it in place. Two flat head screws for 1st shift, one flat head and one round head for 2nd shift, and two round for 3rd shift (very rare) is the configuration. The cast in clock will show the prduction hour, with the first hour at the two dimples.
Usually 2-3 hours to cast/process, then about an hour to Flint depending on orange barrels and backups. Whoops, that was thirty some years ago.
Mark #35760 -
Re: C2 engine casting shift number
Thanks Mark. I have two flathead screws on the casting date insert, so I guess that means first shift. Where is the clock that you refer to?
I see that just above my casting date (in the direction toward the front of the engine) there is a second insert, also having two flathead screws, that appears to have a "1" on it. Could that be an indication of the hour?Comment
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Re: C2 engine casting shift number
Joe –
The other tag that you described is a conveyor ID. Lines 1- 3 produced cylinder & case (block) castings. One & three ran V8’s cast one at a time, while two made four & six cylinder inline cases two per mold. Your tag indicates conveyor one.
The hour marker (clock) is usually located on the left bank rear housing flange. It’s a circle of ten dots about 1.12” in diameter with a screw attached pointer. The double dot is set at the start of the shift and manually indexed every hour with a possibility of a ten hour shift. Casting ID’s were an uncomplicated scrap tracking method at that time.
Take a minute to look at the number next to the GM logo a little lower on the rear flange. This should match the number in the fuel pump flange. Same numbers confirm the patterns were used as a set to equalize wear; some vintage castings are not which is unusual.
Mark #35760Comment
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Re: C2 engine casting shift number
Thanks Mark. I looked at the "clock" casting on the left flange, and the pointer is pointing at the double dot. According to your explanation, that means the block was cast during the first hour of the shift.
Your earlier response said that the two flathead screws on my casting date indicate first shift, so it looks like my block was cast during the first hour of the first shift. This information makes it more plausible that the same-day casting date and assembly date on my engine are legitimate.
By the way, I looked at the survey results in the Noland Adams book. Of the 382 midyear cars for which both the casting date and the assembly date were reported, 51 of them (13%) had casting dates one day before the assembly date, and 6 of them (1.6%) had same-day casting and assembly dates. I realize that the survey results are not officially certified, but they suggest that same-day casting and assembly dates happened more frequently than some people may think.
Interestingly, 4 of the engines in the survey had casting dates that that were one to three days *after* the assembly date. Clearly this was an error on someone's part. I suppose the error could have occurred at GM, or by the survey respondent reading the casting date, or even by an uninformed person building a "restoration" engine.Comment
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