Even on the 300-horse 327s the outlets were only 2". As far as I know, only the high performance Corvettes had the larger outlets. Not even the L-79 Chevelles, Beaumonts, Acadians or Chevy IIs had large outlets. There is a solution...
Here is a link you should check out: http://www.castheads.com/log_systems.php. They make both rams horn & log style manifolds with the large outlets. They are far from cheap but it warrants a look.
What car are these going onto? I know that Chevrolet was still selling the Corvette rams horn manifolds over the counter a few years back. I don't know if they survived the GM bailout.
Another option is extrude honing. If you find a used set of manifolds that fit but are only 2" outlets, you could get them to flow better by getting them extrude honed. What that entails is running a slurry through them with carbide in the mix. It will smooth out and gradually enlarge the ports as the mix is pumped back & forth through the manifolds while hooked up to the extruder machine.
-- Edited by CdnGMfan on Saturday 30th of August 2014 10:19:54 AM
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67 Chevelle Malibu Sport Coupe, Oshawa-built 250 PG never disturbed.
In garage, 296 cid inline six & TH350...
Cam, Toronto.
I don't judge a man by how far he's fallen, but by how far back he bounces - Patton
CndGMfan thanks so much for the info
I am looking into the extrusion thing right now!
Had no idea that process was out there
The car is a 1967 Pontiac Parisienne
Carl thanks for offering up some manifolds
But I actually have a set of extras I bought at the Barrie flea market a few years back
I've just installed the 2.5" Ram horn manifolds on my 1967 Impala SS. It is going to the exhaust shop tomorrow. I will let you know how it goes.
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1967 Chevrolet Impala SS convertible - Ermine White C1 1967 Chevrolet Impala SS 396 - Marina Blue FF 1996 Chevrolet Caprice Classic LT1 2001 Ford F250 CC 4x4
1967 Chevrolet Impala SS convertible - Ermine White C1 1967 Chevrolet Impala SS 396 - Marina Blue FF 1996 Chevrolet Caprice Classic LT1 2001 Ford F250 CC 4x4