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Original Message
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| RE: The most confusing thing about the 390GT's |
| By Dave Shoe - 02/23/2000 11:25:27 PM; IP 206.144.239.80 |
The first wave of emissions requirements came in 1966, the next big wave in 1968.
Ford redesigned the FE head for 1966 with the first small-port heads, and matching small port intakes (the "S" and the "T" intakes). A second generation head became available in 1968 which had a smaller "jellybean" shaped combustion chamber and slightly improved emissions numbers.
I believe the GT did get the CJ-type cam early on, but it was smothered by both the intake and exhaust manifolds, so performance was not an option, no matter what the cam or carb.
The '66-67 GT motors got the CJ cam and the first-generation ('66-'67) emissions heads, though a small number are rumored to have gotten the large-port C6AE-R "AR" head. Still, the intake and exhaust manifolds defined the performance maximums - the head mainly assisted with emissions.
In 1968-69 the GT got the second generation emissions heads, kept the GT cam, but also got the expensive Thermactor emissions assembly to meet the tighter regulations. Ford didn't like spending the money for all this emissions equipment when it really didn't create a popular motor, so in 1969 - with the 428CJ carrying the performance load - the GT motor lost the CJ cam and Holley carb, which cleaned things up enough to allow getting rid of the Thermactor and saving some real money.
Just my latest take on the matter. The "S" intake and GT exhaust manifolds are the common denominators which defined the limits and consistency of the 390 GT thru all the years. The 428PI motors proved that the emissions heads, when combined with a CJ cam, a good intake, and log-type exhaust, was able to make some real power. My 428plain LTD motor was every bit as uninspired as a 390GT, and it had the "S" intake, emissions heads, wimp cam, and log exhaust.
Getting the FE to wake up from a slumber requires attention to the manifolds first.
JMO,
Shoe. |
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