Topic: Mystery to Solve
in Forum: C3 Fuel, Emission Control, and Exhaust Systems
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I've got a mystery for you all to help me solve.
|UPDATED|10/18/2013 2:32:33 PM (AZT)|/UPDATED|
In the midst of restoration I removed the exhaust manifolds from my 1972 (with a turbo hydramatic 400 and AC). (Though the AC is not functioning and the compressor has been removed.)
I had the manifolds ceramic coated because my attempt to do a Por-15 job didn't work very well. There were several places where the Por-15 manifold paint flaked off. Probably because the manifolds were horribly corroded and oxidized so the paint just never would bond to the manifolds. After days of wire brushing and washing dust out of my sinuses I took them in to be sand blasted. While at the shop I decided to save myself some grief this time and spend some money and have them ceramic coated. They look great.
However, I decided to take a closer look at the casting numbers. 3747038. That number is off of a 1965 Corvette as near as I can tell. Also, they are both coded RH... right hand.
Now I'm puzzled. Why would one remove the manifolds from a 72 and replace them with those of a 65? And why two right hand manifolds? Is there any performance gain? Is it pure laziness? Is it a mistake? The engine is original because the engine vin matches the vin on the window post. So I don't have a 1965 engine.
But... why... dang... I'm scratching my head over this one. 
|UPDATED|10/18/2013 2:32:33 PM (AZT)|/UPDATED|
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Lifetime MemberModerator
Duncanville, TX - USA
Joined: 11/8/2003
Posts: 20214
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
Well...let's see if we can shed a little light on the subject....
First, the "RH" does NOT necessarily mean Right Hand. BOTH manifolds have RH on them on MOST exhaust manifolds. In our case, the "Ram's Horn" design manifolds WILL fit either side, since the outlet is centered on the manifold. There were some manifolds that did have extra castings on them for A/C, alternator, and other accessory attachments....those will NOT interchange side/side. Those will also have different casting numbers. 
The 3747038 cast number listed fit MANY Chevrolet engines & vehicles of the era, including Bel Airs/Impallas up to at least '68...also including Corvettes.
Is it correct for the '72? Idano...I could check, but unless you are having it Judged, I wouldn't worry too much about them. If they fit, and function, go with it!
Joel Adams
C3VR Lifetime Member #56 
My Link 
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
That helps some. The research I've done shows a different casting number on the left (3932461) than the right (3989036). Not that it really matters since it surely does work. The only year where my numbers show up was 1965.
I guess nothing would surprise me including the factory throwing some old manifolds on the car. :)
As you say, unless it is to be an NCRS car it doesn't matter. The car is looking better all the time in spite of things like this and a tranny that is no longer numbers matching due to a Bubbaism.
The car will be entered in shows... Just not NCRS shows.
in Forum: C3 Fuel, Emission Control, and Exhaust Systems
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