Tach Dr Dist Housing ID

[Loren L.]

$5 yard sale yields tach drive dist housing with main shaft, tach gear and holder and an apparently generic dist plate. Call it "X". The only one I have out of a car right now is a '62 985. If I put them side-by-side with the tach drive on the left, the housings appear identical, EXCEPT: 1) "X" has TWO approx. 1/4" holes in the FRONT of the housing "stem" - on the 985, the holes are on the back; 2) 985 has an UPSIDE DOWN "331" cast in the housing where the tach gear is carried (Julian date?) and "X" does not; 3) 985 has an oil cap/lid on the upper housing, "X" does not; and 4) "X" has a casting date tape on the lower housing stem that reads "7 A9 2" - January 9th on the second shift in '57, '67 or ? Any educated opinions or just WAGs are welcomed.
Would the main shaft have a part # on it?

[Gene M.]

Re: Tach Dr Dist Housing ID

$5 yard sale yields tach drive dist housing with main shaft, tach gear and holder and an apparently generic dist plate. Call it "X". The only one I have out of a car right now is a '62 985. If I put them side-by-side with the tach drive on the left, the housings appear identical, EXCEPT: 1) "X" has TWO approx. 1/4" holes in the FRONT of the housing "stem" - on the 985, the holes are on the back; 2) 985 has an UPSIDE DOWN "331" cast in the housing where the tach gear is carried (Julian date?) and "X" does not; 3) 985 has an oil cap/lid on the upper housing, "X" does not; and 4) "X" has a casting date tape on the lower housing stem that reads "7 A9 2" - January 9th on the second shift in '57, '67 or ? Any educated opinions or just WAGs are welcomed.
Would the main shaft have a part # on it?

WAG .............. Possibly a marine application?

[Mike Z.]

Re: Tach Dr Dist Housing ID

Your 62 #985 was first year of the tach coupler housing-prior tachs driven off generator. #985 is unique in that it has an oil cock, which went away in 63. Any cast numbers on the housing itself, I believe to be casting/mold ID numbers and have nothing to do with the end P/N. Have rebuilt tons of distributors and some have casting marks/numbers and most do not, some are point, some are TI. The only ID of end P/N is the aluminum ID band. Yes, there are different mainshafts, weights and springs, but the housings (except for early BB) are the same. Later versions have different side oil holes-larger, but still basic housings are the same 63-73/HEI.
So, your X unit (I have seen a cast X before-again, believe to be casting ID): if has an oil cock=62, if not is later.

[Loren L.]

Re: Tach Dr Dist Housing ID

"X" =s unknown; "X does not" have an oil cap as stated; is "7 A9 2" meaningful as a cast date and a workshift indicator; the two housings are NOT the same, with the differences as stated. Thanks.

Your 62 #985 was first year of the tach coupler housing-prior tachs driven off generator. #985 is unique in that it has an oil cock, which went away in 63. Any cast numbers on the housing itself, I believe to be casting/mold ID numbers and have nothing to do with the end P/N. Have rebuilt tons of distributors and some have casting marks/numbers and most do not, some are point, some are TI. The only ID of end P/N is the aluminum ID band. Yes, there are different mainshafts, weights and springs, but the housings (except for early BB) are the same. Later versions have different side oil holes-larger, but still basic housings are the same 63-73/HEI.
So, your X unit (I have seen a cast X before-again, believe to be casting ID): if has an oil cock=62, if not is later.

[Joe L.]

Re: Tach Dr Dist Housing ID

$5 yard sale yields tach drive dist housing with main shaft, tach gear and holder and an apparently generic dist plate. Call it "X". The only one I have out of a car right now is a '62 985. If I put them side-by-side with the tach drive on the left, the housings appear identical, EXCEPT: 1) "X" has TWO approx. 1/4" holes in the FRONT of the housing "stem" - on the 985, the holes are on the back; 2) 985 has an UPSIDE DOWN "331" cast in the housing where the tach gear is carried (Julian date?) and "X" does not; 3) 985 has an oil cap/lid on the upper housing, "X" does not; and 4) "X" has a casting date tape on the lower housing stem that reads "7 A9 2" - January 9th on the second shift in '57, '67 or ? Any educated opinions or just WAGs are welcomed.
Would the main shaft have a part # on it?

Loren------

I've never noted any consistency or pattern with respect to cast "numbers" or "codes" on these distributor housings. Whether the "7 A9 2" represents a date code, I do not know. What I do know is that it does not represent a 1957 date inasmuch as this housing was not being manufactured that early. So, if it is a date and the "7" represents a year, it could only be 1967 or 1977 (for SERVICE). It was out-of-production by 1987.

There was no GM part number on the main shaft. However, the auto cam brazed to the top of the shaft usually has an ID number stamped into it, either on the top or bottom. I do not have a key which relates all of these ID numbers to GM part number. I know some of them, but not all.