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FE Power Forums => FE Technical Forum => Topic started by: Heo on December 31, 2014, 05:06:52 PM

Title: 390 dimesions
Post by: Heo on December 31, 2014, 05:06:52 PM

Can someone give me the max and min dia. On the big ends of the rods and
main bearing bore.I cant find my shopmanual or any other fe literature must
have lent them out to some one that newer returned them >:(
And if someone knows the clearance for TRW L 2143 forged pistons from
the 80s
 Happy New Year to all of you

Title: Re: 390 dimesions
Post by: Ranch on December 31, 2014, 09:21:26 PM

Mains = 2.9412
             2.942

Rod big end = 2.5907
                      2.5912

Can't really help you on the Piston clearance but my old 406 Jahns from the 70's were .007 - .009.   
Clearances were gigantic back then compared to today

Title: Re: 390 dimesions
Post by: BruceS on December 31, 2014, 09:37:52 PM

Heo,
Can't help u on those dimensions, but it sounds like you're getting that P code back together!  More power to ya, and Happy New Year!

Bruce

Title: Re: 390 dimesions
Post by: Joe-JDC on December 31, 2014, 09:40:52 PM

Most all piston manufacturers sell their pistons in an overbore size.  If the piston is +.030, .040, etc., then if you bore the block to the overbore size, the proper clearance is built into the piston.  Takes the guess work out of tolerances.  Joe-JDC

Title: Re: 390 dimesions
Post by: Heo on January 01, 2015, 01:04:14 PM

Yes Joe Most of the time its that way
Why i ask is i have a 390 bored 060
assembled by some real experts ::)
it got some scuffing and scratches in
most cylinders,bent rods,camplug wrong way
etc etc
So im after max clearance. Maby i can
hone the ugly cylinders, And save the block
since its the original block from the car.
The clearance now is just 0.0025-0.0035
(some over some under 4.11 inch)
and i think thats to thight.As i remember it
the forged pistons wanted around 0.005
but i can be wrong

Title: Re: 390 dimesions
Post by: Heo on January 01, 2015, 01:15:06 PM

Well Bruce i dont know ....The p code was a can of worms when i
started to go through it.

I opened another 390 today that was a frech rebuild that
leaked water to the oil perhaps i have time to preassure
test that block tomorow if the block is fine i go for a
stroker kit with that one

Thanks ranch then i can meassure that

Title: Re: 390 dimesions
Post by: Joe-JDC on January 01, 2015, 04:03:30 PM

.0055-.007 should work well if the ring gaps are correct.  Some folks just hone and re-ring at least three times before boring again.  It was not uncommon to go out to .009-.010" clearances with forged pistons.  Joe-JDC.

Title: Re: 390 dimesions
Post by: Heo on January 01, 2015, 06:21:51 PM

Thanks Joe
Thats some numbers that sounds more familiar
with what i remember we used in the 80s

Title: Re: 390 dimesions
Post by: cjshaker on January 02, 2015, 06:36:25 AM

.0025-.0035 is definitely too tight for forged pistons! :o  No wonder the cylinders were scuffed. I'm surprised they weren't peeling aluminum off of the pistons!

Title: Re: 390 dimesions
Post by: Heo on January 02, 2015, 02:14:33 PM

Today i calibrated my micrometer and my cyl indicator
and gues what? All cyls. are under 4.11i have about
0.0019-0,0020 its a wounder its not seized up :o
I thought i was one revolution wrong on the indicator
I must meassure again tomorow when im not so tired