Exhaust Heat Riser 327/300hp

[Gerard F.]

Re: Exhaust Heat Riser 327/300hp

Jerry,

The part number change from 3746838 to 3887024 was July 1966 as Per Chevrolet Parts History for service parts which is very close to the assembly manual date change of 6-14-66.

I agree with Joe that the "6844" and "3746844" (Terry's) are casting numbers (and possibly part numbers) for only the weight.

I do not BELIEVE that your "B 7" is a date code and this is why. The original heat riser on my 1970 Camaro SS350 RH exhaust manifold (Casting # "3973432" and date code "E 29 0" or May 29, 1970) has a casting number "B 13" and "9428" on the weight. The GM part number for the heat riser in the 1970 Camaro AIM as well as in my 1970 Chevrolet Parts Catalog is 3887023. This manifold is NOT the "rams head" type so the heat riser is different.

The 1970 Chevrolet passenger car lists GM # 3887024 as the heat riser in the AIM which is the same part # as the 1967 Corvette because both cars use the "ram head" type of exhaust manifolds.

I now have another part to research. The "B 7" and "B 13" might be mold numbers.

Dave

Dave,

I understand the date code and part number I assumed are probably for just the weight.

However, was there another area on the heat riser where there was a part number and a date code. In redoing my original I never noticed one, maybe I missed it.

Here is a picture of my original 67 heat riser, when in 2005 I took it off for the first time:



I have owned the car since 68, and was always amazed how the car in a cold start always did that left to right exhaust cycling in cold weather.
Never touched it until 2005 when I replaced the exhaust system.

But made sure to put the original back (after the shop put in a replacement, and put it in wrong).

But I'm not going to take it off again, to check the numbers

Best regards,

[David L.]

Re: Exhaust Heat Riser 327/300hp

Jerry,

I believe that I have some other used original heat risers stored somewhere in my garage that I want to examine but it may take some time to find them.

I believe that the difference between the 3887024 and 3887023 heat riser is the shape of the weight.

Dave

[Tracy C.]

Re: Exhaust Heat Riser 327/300hp

Thank You all!
Of coarse mine is a little different:
I have it installed with camfer down but mine has no donut, my exhaust pipe is a ball fitting into the socket on heat riser.
So it is exhaust pipe to heat riser to small flat gasket to manifold
My weight is pointing up not sideways.
How would I tell if heat riser is original.
Thanks again!
Terry

Based on your picture, you need to rotate the riser clockwise 60 degrees as the weight should be on the rear of the manifold outlet and pivot downward while opening.

tc

[David L.]

Re: Exhaust Heat Riser 327/300hp

Dave,

I understand the date code and part number I assumed are probably for just the weight.

However, was there another area on the heat riser where there was a part number and a date code. In redoing my original I never noticed one, maybe I missed it.

Here is a picture of my original 67 heat riser, when in 2005 I took it off for the first time:



I have owned the car since 68, and was always amazed how the car in a cold start always did that left to right exhaust cycling in cold weather.
Never touched it until 2005 when I replaced the exhaust system.

But made sure to put the original back (after the shop put in a replacement, and put it in wrong).

But I'm not going to take it off again, to check the numbers

Best regards,

Jerry,

Here are photos my original heat riser (GM # 3887023 in 1970 parts catalog) from my 1970 Camaro SS350 "3973432" exhaust manifold dated "E 29 0" (May 29, 1970). Note that the weight is basically CENTERED (1st and 2nd photo) on the arm. The weight has the following casting numbers "B 13" and "9428" on one side and "X" on the other side. It is now in the "museum" section of my "collection".

The weight on the 3746838 and 3887024 heat risers (like your heat riser) is OFFSET with respect to the arm.

Dave

[David L.]

Re: Exhaust Heat Riser 327/300hp

Dave,

I understand the date code and part number I assumed are probably for just the weight.

However, was there another area on the heat riser where there was a part number and a date code. In redoing my original I never noticed one, maybe I missed it.

Jerry,

Below are photos of a NOS 3887024 heat riser that was sold over the counter from July 1966 to May 1976.

The weight has the following casting letters & numbers:
"G"
"L3-"
"6844"

There is also a "UP" casting as shown in photo #2.

GM # 3746838 was replaced in July 1966 with GM # 3887024 which was then replaced in May 1976 with GM # 362652 as per Chevrolet & GM Parts History.

I believe the only difference is as follows:
The area with the "UP" casting on the 3887024 heat riser measures about 1/2" thick.
This same area on the 362652 heat riser is about 1" thick.

Dave