400 ?

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Jan 19, 2005 | 08:08 PM

MichaelMuck

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400 ?

I have a ranchero that has a 71 400 in it. I also have a pair or aussie heads I going to put on it. compression would be about 10.5 to 1? what octane gas would I have to use

Jan 19, 2005 | 09:05 PM

grclark351

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From: chicago burbs

i figure the CR will be closer to 11:1. premium if you're lucky, but i doubt it. you'll need a cam with a lot of overlap to keep cylinder pressure down, or use reverse dome pistons that come up to the top of the bore to take advantage of the quench chamber in the heads.

Jan 19, 2005 | 11:28 PM

Torque1st

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Premium +octane boost, and lots of it. The 71 Motor had 9:1 compression. Leave it alone!

Jan 20, 2005 | 01:46 AM

MichaelMuck

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I can get 100 oct gas for 2.00 per gallon (family), would that be hi enough?

Jan 20, 2005 | 09:07 AM

74 F100 351m

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From: Okla.

I would say 130oct.

Jan 20, 2005 | 12:40 PM

Torque1st

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The 71 400 was the best 400 ever produced, leave it stock. Upgrade it with a 4V manifold from Edelbrock or Weiand. Slap on a #1406 Edelbrock carb. Upgrade to DS-II Ignition. Run it!