LMM: LMM with 222,000 tear down rebuild

malibu795

malibu795

misspeelleerr
Apr 28, 2007
8,109
461
83
42
in the buckeye state
PureHybrid said:
He said it was bored to 4.098, if that were true the bore would be 4.106
Click to expand...

The short stick is .008" ptwc is what they set the clearance up for.. And it's too loose for what I'm doing and how I use it. Piston/bore diameters be damned, .008" ptwc it too loose.

Big power forged pistons sure I'll run that clearance

Under 500hp absolutely not. Put 100-150,000 miles on it and it will eat oil like crazy, not too mention rings will probably never fully seat, compounding the oil consumption issue.. Furthermore, Knowing I'll put those miles down before I get ontop of financial things and have cash to build another short block(~$5000.00 to duplicate the short block I got now) It just doesn't seam smart.
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
8,109
461
83
42
in the buckeye state
WolfLLY said:
Oh I missed where he said piston measured 4.090.
Click to expand...

I was told bore is 4.098 ptw is .008 that math would make pistons 4.082..

When I asked the machinist what PTWC was.. He said .008". When I asked what the final bore was.. He said 4.098"
I didn't bother to have him break out a dial bore guage or outside mic..
Here's my quote
malibu795 said:
Bore is 4.098
Ptwc is .008"
Piston would be 4.082..
.. If it was .005-6" I'd run it.
Click to expand...
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
8,109
461
83
42
in the buckeye state
PureHybrid said:
So you don't have a true measurement of the piston skirt, just the specs that Mahle sent.
Click to expand...

I don't have that in hand. The .090 was typo. I subtracted b.008 vs .016 from .098 .
All I know bore was 4.098 with .008" ptwc
Reverse math puts pistons at 4.082

I will when pick the block up Tuesday/Wednesday.. And seeing they are used I'm sure they are different from NIB size.
 
Fingers

Fingers

Village Idiot
Vendor/Sponsor
Apr 1, 2008
1,714
84
48
White Oak, PA
Guys, the pistons are not round, or the same from top to bottom. The Fattest part on the ovals is just above the bottom of the skirt perpendicular to the pin. There is very little growth from heat here and the tolerances should be kept tight.

But again, EVERYONE, just bore the damn block to the spec 4.055, 4.075, or 4.095 and get off the PTW.
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
8,109
461
83
42
in the buckeye state
Fingers said:
Guys, the pistons are not round, or the same from top to bottom. The Fattest part on the ovals is just above the bottom of the skirt perpendicular to the pin. There is very little growth from heat here and the tolerances should be kept tight.

But again, EVERYONE, just bore the damn block to the spec 4.055, 4.075, or 4.095 and get off the PTW.
Click to expand...

From talking with mahle tech and knowing new spec is .0022-.0025".. I know straight of the bat .008" is not right. Not even close!

.008" isn't tight on a cast dmax piston its extremely loose. It darn near maxed out on service limit spec!

I'd be back in the engine in 12-18 months or sooner if I ran with it..
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
8,109
461
83
42
in the buckeye state
Results from too much piston too wall clearance under a load on a BIg block Chevy I had
1918834_1244552267497_3514627_n.jpg

1918834_1244552307498_3155026_n.jpg


Saying it doesn't matter I'm calling bullshit
 
D

DixonM

New member
Nov 20, 2014
37
0
0
Florida
If it were mine and I wanted XX amount of piston to wall I always bring a piston to the machine shop for them to measure and double check them selves with good idea to use sharpie and mark clearance wanted on piston top.
 
PureHybrid

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
3,439
444
83
Central OH
malibu795 said:
From talking with mahle tech and knowing new spec is .0022-.0025".. I know straight of the bat .008" is not right. Not even close!

.008" isn't tight on a cast dmax piston its extremely loose. It darn near maxed out on service limit spec!

I'd be back in the engine in 12-18 months or sooner if I ran with it..
Click to expand...

Yea I was reading it as a total of .008 not ptw from what was posted, sorry
 
PureHybrid

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
3,439
444
83
Central OH
Fingers said:
Guys, the pistons are not round, or the same from top to bottom. The Fattest part on the ovals is just above the bottom of the skirt perpendicular to the pin. There is very little growth from heat here and the tolerances should be kept tight.

But again, EVERYONE, just bore the damn block to the spec 4.055, 4.075, or 4.095 and get off the PTW.
Click to expand...

Geez don't be such a scrooge

I thought stock bore was 4.060?

And yes, we know the pistons aren't round. That's why I asked what the skirt measured, there's more than one person here that's put their share of engines together.
 
malibu795

malibu795

misspeelleerr
Apr 28, 2007
8,109
461
83
42
in the buckeye state
DixonM said:
If it were mine and I wanted XX amount of piston to wall I always bring a piston to the machine shop for them to measure and double check them selves with good idea to use sharpie and mark clearance wanted on piston top.
Click to expand...
I took complete disassembled short block to them..
Camshafts got keyed
rotating assembly had balance double checked
Block had bore, decked and main done.
Crankshaft was already keyed when I bought it.
Everything washed.
Crankshaft polished

Fleece performances's Front office dropped the ball relaying the message to the machine shop.
 
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