# 67 ho exhaust manifolds aftermarket best ones available?



## fiesta62 (Jan 12, 2011)

hi, i am interested in finding original ho manifolds for my 67 gto but i have learnt repros have the casting codes so possibly there is a good set of repros made that would be the same as originals and just as good, but i know originals have built in pass plates and also the heat riser , does anyone know what are the best aftermarket ones available?....and do they have pass plates and heat riser built in?....thanks


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## FNG69 (Nov 15, 2009)

I’ve looked at the sales brochures, shop manual, restoration guide, etc… I cannot find a picture of the heat riser set up on a factory HO (or Ram Air) exhaust manifold – the Ram Air restoration guys say that the “boss” is there on the reproduction casting for the heat riser, but It looks like the “boss” is set up so that the flapper would be on the front of the manifold, not on the side; that would put the spring on the back of the manifold, and I cannot imagine that is correct..

Guess I'm saying we both could use some help on these?? Thanks, Les


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## Topkat (Sep 9, 2010)

I believe OPGI was the correct manifolds.
the spring in on outside of the passenger side
good luck


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## old66tiger (Nov 2, 2011)

No idea about the heat risers. Never seen them in the originals. Whatever RA manifolds you get, plan on taking them to the machine shop and have them surface plated flat. This will allow you to install them on the heads without anything but a thin bead of silicone. no gaskets required. Also, may need to port them to get the ports to line up


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## fiesta62 (Jan 12, 2011)

old66tiger said:


> No idea about the heat risers. Never seen them in the originals. Whatever RA manifolds you get, plan on taking them to the machine shop and have them surface plated flat. This will allow you to install them on the heads without anything but a thin bead of silicone. no gaskets required. Also, may need to port them to get the ports to line up


hi, my 67 is a ho so the ports will be fine, i have found a set of original ho manifolds with the heat risers and correct codes so all good, bit of rust but nothing a clean up wont fix, not sure if i need to re- surface them as you suggest, i figured i will just use a gasket thats the usual way isnt it ?...


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## RA6T7GTO (Jul 2, 2011)

always a good idea to make sure the gasket surface is flat, these original manifolds are old and im sure they are warped from heat and age, put them on a belt sander to clean them up


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