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Original Message
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| RE: what heads do I have |
| By Dave Shoe - 09/18/2000 10:41:24 PM; IP 216.243.158.156 |
They are 1967-only heads that came on many 390, 428, and possibly 428PI(& Shelby GT500) motors. They have the medium sized (about 72cc or so)combustion chamber. Common production alternatives are C6AE-R (big runner, high-exit, good power heads) and C6AE-U (nothing special).
C7AE-A are a full-emissions head (small runners), not a performance head, but you can make some OK power with them. Thermactor ports may (Calif) or may not (49 States) be drilled.
The other person you refer to probably had 14-bolt exhausts in his heads because they were from a Fairlane/Mustang 390. The two center-bottom bosses were not drilled in these cars.
Only the 428CJ/SCJ got the 16-bolt pattern (definitely a different head), which is not compatible with the 14-bolt pattern. You've obviously noticed the upper-outer two bolts in the 14-bolt pattern are relocated slightly below the normal location. This was not one of Fords better ideas. Holes in 16-bolt heads are all normally placed.
You did not mention the type of headers you have, but I assume you have a port-mismatch problem between those emissions heads and the headers which is causing an improper gasket crush (leaks) and poor performance (the port mismatch).
Most FE headers are designed only for the high-exit heads common to all 1965-earlier heads (pre-emissions), and only a few emissions-era heads such as C6AE-R and C8OE-N. Your exhausr port exits the heads 5/16" lower than the earlier heads, meaning the weld bead is not being crushed into the gasket along the bottom of the port.
Either you need to fit FPA headers with the low-flange to your heads, or you need to get a large port head like the C6AE-R or 1965-earlier head. Note the 1965-earlier heads can ONLY fit the 8-bolt exhausts (Galaxie or pickup only), because the 16-bolt bosses were added to all FE heads starting at the beginning of 1966 (Fairlane/Mustang compatibility).
When using headers you MUST use the manufacturers header gaskets, not the gaskets that come in the rebuild kits. Header manufacturers use a gasket which closely fits the port, allowing good weld-bead crush, thus good sealing -AS LONG AS YOU USE THE RIGHT HEADS. Also, make sure you get the correct "raised exit" or "low exit" gaskets to match your head and header.
Hooker, Hedman, and most other header manufacturers ONLY make headers and gaskets for the high-exit heads. FPA (fordpowertrain.com) makes Tri-Y headers and gaskets for both types of FE exhaust ports - you need to specify when you buy.
Yes, it's a crime that most header manufacturers don't mention this problem, but they sell more headers if they don't have to actually FIT the motor properly.
Note that the most common small runner, low-exit FE heads are C6AE-U, C7AE-A, C8AE-H, and D2TE-AA. You can drill these heads for the 16-bolt pattern, but be sure to drill no deeper than the lower bolt holes to avoid hitting coolant.
Good luck.
Shoe.
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