ford 390

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Apr 7, 2004 | 10:00 PM

#46

rusty70f100

Post Fiend

Joined: Jan 2003

Posts: 8,600

Likes: 4

From: Iowa

Stock pistons were cast, and he's probably using forged, and they expand more than stock cast pistons. Of course, they could have screwed up. When I had my block bored, I took the pistons with me, and told them what bore clearance I wanted. When they were done, they told me they went .034" over to get the dimensions I wanted.

Apr 7, 2004 | 10:14 PM

#47

Randyb12

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Joined: Jul 2003

Posts: 1,268

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From: Eureka, Ca.

I have forged pistons in my 390. 30 over. the block was bored 30 over also. No problems even at 215F.

Apr 7, 2004 | 11:53 PM

#48

fordman428

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Joined: Nov 2003

Posts: 1,888

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From: Iowa

i have aluminum pistons in my .060 over 390 and i guess ill she if she goes or blows when i fire it up for the first time friday.

Apr 8, 2004 | 12:11 AM

#49

jimshaver

Senior User

Joined: Mar 2004

Posts: 101

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From: pittsburgh area

14.7 to 1 is the generally desired ratio of the hydrocarbons in the ehaust dunno if it helps at all but thats what they say here in the PA emmissions laws