mopar big block high performance manifolds ?
- Thread starter Douglas
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1970FuryConv
Old Man with a Hat
For 1969 log manifold outlet diameter was 2.00". HP exhaust manifold outlet diameter was 2.25"
HP exhaust manifolds have better shape and flow IMO.
Because of the up sweep to HP manifolds, they will burn valve cover paint if a barrier gasket is not used. Exhaust manifold gasket MS 90425 will prevent.
Also, HP exhaust manifolds require a special bolt kit to install. They look cool when done. Hadn't learned my lesson about MS90425 when I took these photos
HP exhaust manifolds have better shape and flow IMO.
Because of the up sweep to HP manifolds, they will burn valve cover paint if a barrier gasket is not used. Exhaust manifold gasket MS 90425 will prevent.
Also, HP exhaust manifolds require a special bolt kit to install. They look cool when done. Hadn't learned my lesson about MS90425 when I took these photos
thank you
Here is a link from tti for factory exhaust manifold casting numbers and applications. I would try to find some of the ones like I have with the 2.5" exhaust flange (PN 2951865 & 2899879) for the best flow depending on what kind of HP your motor has. I took mine and had them baked to release all of the oils, media blasted, then coated with a thermal insulating coating called zybar(similar idea to ceramic insulating coating but this product seems to be more durable and have a higher max temp rating). Make sure if you have someone coat them to get them coated inside and out as best as possible. It helps significantly and you shouldn't need the heat shield but likely plug wire insulating boots.
https://www.ttiexhaust.com/Classics-Ex/MfdCastingNo-383.pdf
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