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Original Message
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Those are raised-exit heads. |
By Dave Shoe - 04/14/2002 10:57:42 PM; IP 63.233.226.246 |
C6AE-Rs differ from CJ heads in two ways - thay have an "anti-reversion" type lip at the exit of the exhaust port which can be ground away with little difficulty (making the high-exit more obvious), and they need to have the throats dressed to properly fit CJ valves. Once done, these flow about the same as CJ heads.
Note that CJ heads are cast for 2.03/1.55 valves just like all the other FE heads, but they were "dressed out" in the engine plant to fit the larger valves.
Also note the "AR" lip is probably not actually there for anti-reversion purposes. It's likely there to shrink up the high-exit exhaust runner in order to seal against the low-exit Fairlane/Mustang exhaust 390 manifold. I will refer to it as an "anti-reversion" lip until I lern more about it's design intent. It is a trianguular tab at the top of the exhaust port about 5/16" tall, and extends about 1/2" deep into the exhaust port, where it triangularly tapers down to nothing. Pretty darned easy to cut away. Easier than removing the thermactor bumps, for sure.
Shoe. |
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