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#1
04-25-2020, 09:37 PM
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#66 heads compared to 6x4's on a 400
What and how much difference in actual performance between these heads on a 9790071 400? Just curious ?
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#2
04-25-2020, 09:46 PM
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Forget the #66 heads for use on a 400.
The compression will be somewhere in the low 7:1 range at best. The 114cc chambers are only suited for low compression 455 engines in the low to mid 8:1 range.
__________________
1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
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#3
04-25-2020, 09:56 PM
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I'm checking for another guy that says the engine has alot of power but I thought he could get more . Originally I think most of them had the 670's on them for that year . Thanks .
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#4
04-25-2020, 10:16 PM
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The #66 heads were used only on 325 HP 1971 455 4-barrel engines that were factory rated at 8.2:1 compression.
I can’t imagine any 400 running strong with those heads at around 7:1 compression. The 670 heads were used on high-compression 400 performance engines and 428 big car performance engines in 1967 only, compression was 10.5 to 10.75:1. The 6X-4 heads would make good 400 performance heads but hard to get above 9:1, the #66 heads not so much at 7:1.
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1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
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#5
04-26-2020, 06:22 AM
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With that heads 114 CC chamber it would not even make for a good Head to use on a 400 even if you where going to Turbo or supercharge it , and forget trying to go the dome piston route as the plug / flame front shrouding would make for a terrible power loss!
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#6
04-26-2020, 10:33 PM
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Thanks guys that helps for sure !
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