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Old 09-21-2019, 04:52 AM
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Lee Stewart Lee Stewart is offline
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According to the literature at the time, the 1967 Shelby GT 500 has a 428 Police Interceptor engine with dual 4bbl carbs and is rated at 355 HP.

According to Ford literature, the 428 PI engine with a single 4bbl carb is 360 HP.

Also according to Ford literature, when you change a single 4 bbl intake with a dual quad intake, you get an additional 25 to 30 more HP.

So the real rating for the 1967 GT 500 should have been either 385 or 390 HP.

But according to Shelby/Ford . . . when you install dual quads you lose 30 to 35 HP

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