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Original Message
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| Yeah, I was just kidding a bit about that. |
| By Dave Shoe - 04/25/2003 9:36:09 AM; IP 216.243.176.34 |
I can relate to the numbers-matching interest, but can more so recall how much time and money (mainly time) it takes to find the "correct" parts, when so much FE stuff is exactly the same.
I suspect performance is not the main goal here, but big block presence and originality is, as an original convertible Mustang does have a neat presence, not to mention higher resale value. Still, should you decide to go with Edelbrock, CJ, 427, C6AE-R, or or 1958-65 FE heads, then the FPA headers for a 390 Mustang will be incorrect, you'll need the ones for a 428CJ, due to the alternate position of the exhaust port on these heads. Also, it'll be desirable to drill and tap the undrilled exhaust bolt bosses if you use a truck engine as the basis of the build, sinc the diagonal bolts are best suited to tight fitting Mustang/Fairlane engine bays. Just had to mention that, as the port mismatch causes exhaust leaks as well as non-optimal performance.
Note that C6AE-J, C6AE-L, C6AE-U, C6AE-Y, C7AE-A, C8AE-H, and D2TE-AA all have low positioned exhaust ports which sit 5/16" lower than the other FE ports, and these comprise the bulk of 1966-70 heads, and all of the 1971-later FE heads on cars and trucks. Diectly associated with the low-exit exhaust is the small-runner "velocity" intake port which first showed up in 1966 to help the FE meet new emissions laws. The stock head performs great up to about 400 horsepower, beyond that level of tune, you gotta start porting it. It's the best performance head for milder 352/360/390 builds, as it has great streetability in combination with efficiently flowbenched port design, but it lacks the raw air passing power of the earlier head, something that starts to become apparent at about 400 horsepower.
C8AE-H heads woud be correct for your car (C7AE-A are O.K. early in the 1968 model year, JMO), and if it was a "GT" cammed engine, it would need thermactor ports drilled in the head, and a thermactor system on the car to meet tougher 1968 emissions laws. At the start of the 1969 model year the 390GT engine disappeared, as did expensive thermactor on the 390, resulting in the decammed 390IP as the top dog 390.
Sweat the thermactor conversion some other time. Just get the car running nice now.
JMO,
Shoe. |
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 |  390 -- Robin Scribailo, 04/21/2003
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| |  | Yeah, I was just kidding a bit about that. -- Dave Shoe, 04/25/2003 |
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