C1 1957 Original exhaust pipe flange nuts

[Dan P.]

According to 1957 and 1962 Corvette and 1955 /1957 Passenger car ALL models even 6 cylinder AM's have the part number for the exhaust pipe flange nut as 3671946.The 3829086 crimped style flange nut started in 1963. I could not find the 1957 3671946 nut in the standard parts . The reason is according to the original drawing it had anti cease on it .So it carried a different part number. A friend has the original drawing but can not fine it. Original 29,000 mile 1955 Corvette with original exhaust and 1955 passenger cars with 4,000,12,000 and 13,000 mile All had regular steel nuts .See pictures . Also look at the picture of the original style nut with square corners and a register on one side so the corners will not dig in when tightened . All originals nuts were made like this .They are being reproduced .

[Dan P.]

Re: C1 1957 Orginal exhauste pipe flang nuts

Here are picture of Bill Conrads exhaust nuts . Original exhaust on a 24,000 car . Original round mufflers . The nut are regular 3/8 nuts not crimped nuts .

[Dan P.]

Re: C1 1957 Orginal exhauste pipe flang nuts

Just found out the 1958 AM also has the 3671946 nut for the header pipe

[David B.]

Re: C1 1957 Orginal exhauste pipe flang nuts

Notice you have posted this thread in the past, apparently with no helpful response. Suggest you clear the table and start again.
1. Part # 3671946 is not a Standard Engineering part number therefore it may or may not be listed in a Chevrolet Standard Parts listing.
2. If a fastener under control of Engineering Standards can not be found to meet a GM Division's requirement that Division can design and will assign a part # from their block of numbers, hence #3671946
3. Your reference to a blueprint for # 3671946 seems to confirm item #2. Try to find print to verify!
4. Exhaust pipe flange nuts ARE NOT regular 3/8 nuts.
5. I would speculate your reference to anti-seize compound the reason for a unique part number is erroneous rather, the service part # 838780 seems to point to the difference as being dimensions of 3/8-16 x 3/8 thick (special thin). This service part # is in GRP. 3.277 and as you indicate used by all series cars. The ONE big exception from the production part is the service nut is BRASS. My guess is this would have been too expensive to use in assembly but not service.
6. FIND THAT BLUEPRINT TO VERIFY!!!

[Dan P.]

Re: C1 1957 Orginal exhauste pipe flang nuts

Thanks i friend who says he has the drawing but can't find it .