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Original Message
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| They'll work fine. |
| By Dave Shoe - 07/16/2001 10:52:17 PM; IP 216.243.158.129 |
The 406 exhaust headers have oversized runners which fit both the raised exit (pre-emissions) head and lowered exit (emissions-era) head. How Ford engineers had the insight to "oversize" the exhaust manifold ports four years before the low-exit "emissions" head was designed is beyond me. I can only guess the earliest FE prototype heads may have had excessively large exhaust runners that matched this larger manifold port.
Note that some later cast iron headers only mate properly to high-exit heads. Likewise, 390 unibody exhaust manifolds only properly mate to low exit heads, though they also sorta work with anti-reversion (C6AE-R, 427marine, etc) heads.
The 406 intake manifold will not have a perfect port match with the C8 head, but if you use the pre-emissions type of intake gasket (for the tall intake runner), then it will properly crush the gasket and will not leak. Flow should be quite good.
I sorta wonder if the tall intake runner can puddle a small bit of gasoline as it joins with the smaller head runner, but I've never heard this to be a problem. To be sure, Ford policy during the '70s was to sell short-port heads to customers with damaged tall-port heads, so this is certainly not a major issue.
Keep in mind that FE iron heads do not have thick metal like aluminum heads do, so you want to be careful about porting excessively, should you try to match the tall intake runners.
Shoe. |
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