exhaust manifold numbers. please help.
09-03-2003, 02:25 PM
#1
Heel & Toe
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exhaust manifold numbers. please help.
I have two 2" rams horn exhaust manifolds I am trying to identify.
one reads: 3932461 gm rh 18
and the other is: 3932461 gm rh 17
I'd appreciate any help decoding these or where I could find the info.
Thanks,
Matt :confused:
[Modified by MJR72, 7:26 PM 9/3/2003]
one reads: 3932461 gm rh 18
and the other is: 3932461 gm rh 17
I'd appreciate any help decoding these or where I could find the info.
Thanks,
Matt :confused:
[Modified by MJR72, 7:26 PM 9/3/2003]
09-03-2003, 04:23 PM
#2
Melting Slicks
Re: exhaust manifold numbers. please help. (MJR72)
The 3932461 is the cast/part number. These manifolds were cast the same but some were drilled for the AIR connections and some were not.
The GM lets you know GM made it.
The RH17 and RH18 I believe standard for the casting mold version. I have seen 16, 17 and 18 on 1976 Corvettes. On 73's the number is a 3,4 or 6 that I have seen.
On the mid teen number manifolds there is a small raised square block cast into them where the two side section meet. This block is not on the earlier manifolds. It could have been added to help eliminate cracks at this point.
Also on the back side of the manifold is a date code of a letter and one or two numbers giving the month and day of the casting. Note the year is not included.
Roger
The GM lets you know GM made it.
The RH17 and RH18 I believe standard for the casting mold version. I have seen 16, 17 and 18 on 1976 Corvettes. On 73's the number is a 3,4 or 6 that I have seen.
On the mid teen number manifolds there is a small raised square block cast into them where the two side section meet. This block is not on the earlier manifolds. It could have been added to help eliminate cracks at this point.
Also on the back side of the manifold is a date code of a letter and one or two numbers giving the month and day of the casting. Note the year is not included.
Roger
09-03-2003, 09:03 PM
#4
Heel & Toe
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Re: exhaust manifold numbers. please help. (MJR72)
MJR72,
My numbers book only covers 1968-72 but shows the casting numbers on those manifolds where used for 1972 200 H.P. & 255 H.P. engines. They were also used in 70 & 71. The RH & LH usually indicated whether they were right handed or left handed (right side or left side). As far as the date codes go I am pretty sure at least on the 68-72 that they were stamped with a letter and a number - I8 would indicated casting month and year this example would be Sept 1968 as model year production for those years began on January which would be the "A" month, February being "B" month and so on. I used I8 as an example as sometimes its easy to have a I look like a 1. I can't really tell you if these casting numbers were also used on the 1979 but the dates if they are I7 and I8 (Sept 77,78)may more match that year then they would for 1972. Good luck!
Rich
My numbers book only covers 1968-72 but shows the casting numbers on those manifolds where used for 1972 200 H.P. & 255 H.P. engines. They were also used in 70 & 71. The RH & LH usually indicated whether they were right handed or left handed (right side or left side). As far as the date codes go I am pretty sure at least on the 68-72 that they were stamped with a letter and a number - I8 would indicated casting month and year this example would be Sept 1968 as model year production for those years began on January which would be the "A" month, February being "B" month and so on. I used I8 as an example as sometimes its easy to have a I look like a 1. I can't really tell you if these casting numbers were also used on the 1979 but the dates if they are I7 and I8 (Sept 77,78)may more match that year then they would for 1972. Good luck!
Rich
