I have someone telling me the 3968889 exhaust manifold will work on my car. The book says it takes a 3880827 manifold. Does anyone know the difference between the 2 manifolds and if the 3968889 will work on a 69? Thanks!
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Re: What's the difference between a 3968889 and a
George-----
I think you're talking about a 3969869 casting manifold. This manifold casting was used on all Corvette big blocks from 1970 through 1974 for the driver's side. The difference between it and the earlier 3880827 involves the configuration of the runners and, especially, the configuration of the outlet. The 3969869 can be used on any 65-69 Corvette IF the 70-74 left forward front exhaust pipe is also used. However, this exhaust pipe may need some modification for use on 65-67 models. For 68-69, the 70-74 left front exhaust pipe will fit perfectly.
Also, keep in mind that like the 3880827 casting, the 3969869 casting was finished into 2 different exhaust manifold PART numbers (which appear nowhere on the manifoilds). One has fittings for AIR and the other doesn't. Since all 1969 Corvettes have AIR, if you use the 3969869 casting, you'll need the manifold WITH AIR fittings.In Appreciation of John Hinckley -
Thanks Joe! Since I'm buying a new exhaust will?
it work if I just put in the entire 70-74 exhaust system on. Or will they not fit the 69 car I have. And thanks again, you sure are an expert on this stuff!Comment
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Re: Thanks Joe! Since I'm buying a new exhaust wil
George-----
Yes, basically you will HAVE TO use a complete 1970 exhaust system (except tips) if you want to use the 3969869 left side manifold on a 1969 big block. Here's why: ALL 1969 Corvettes were originally built with a 2" exhaust system. Therefore, the forward pipes for big blocks were unique to that year and engine application. NO other Corvette big blocks of ANY other year used a 2" exhaust system.
For 1970, all big block exhaust systems were 2-1/2" and the GM casting #3969869 left side manifold was first used. So, there is no 1969 configuration left forward pipe ever made for compatibility with the 3969869 left side manifold. When using this manifold on a 1969, one has to convert the entire 1969 system to the 2-1/2" configuration system as used for 1970-72 Corvettes.
You'll also need to change the transmission "ox bow" bracket/clamp to the 2-1/2" type. The "ox bow" bracket is different for 2" and 2-1/2" systems. It's also different for manual and auto trans applications.In Appreciation of John HinckleyComment
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Thanks Joe! Seems kinda dumb to change.
I'll wait for the right parts....DUHHH! Thanks again what was I thinking!Comment
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Re: Thanks Joe! Seems kinda dumb to change.
George-----
Oh, I don't know---change might not be a bad thing in this case. It all depends what you're after. If you want to go the strict originality route, then the 2" system is what you should seek. It will be VERY difficult to put together a competely and totally original system. However, it will need to be a 2" system to get you even close to full judging points.
On the other hand, I consider that a 2-1/2" system is the way to go from a performance perspective. There might not be a huge difference in actual performance, but I still prefer the 2-1/2" system. Chevrolet did, too, for all big blocks EXCEPT 1969.
If you go the originality route, the GM #3880827 manifold is not that hard to find. You can even get an excellent reproduction for about 300 bucks.In Appreciation of John HinckleyComment
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Re: Thanks Joe! Seems kinda dumb to change.
Joe,
-------I remember looking at the bottom-side of my brand new 1969 427/435 and wondering what in the world was going on at St.Louis. I actually thought they somehow installed a small-block exhaust on my otherwise beautiful new Corvette. Shortly thereafter I installed headers and a complete 1968 big-block exhaust. I can tell you that performance was definetly up (way up) in that instance. Ran around the country in rural Ohio for a week with no mufflers waiting for the parts to come in at my dealer. That was fun!!!.........Bill SComment
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