390 dimesions

[Heo]

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

[Ranch]

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

[BruceS]

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

[Joe-JDC]

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

[Heo]

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

[Heo]

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

[Joe-JDC]

.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.

[Heo]

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

[cjshaker]

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

[Heo]

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
I thought i was one revolution wrong on the indicator
I must meassure again tomorow when im not so tired