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A little help before I go to the machine shop

I Have a VERY clean block I've been stitting on for years that was "rough" bored .040 over a long time ago and it has about .002" of taper.
The Widest parts are at the very top. I'm worried that I may end up paying for junk in the long run and would like to be reasured that this taper
can be removed without further widening the top portion of the bore.

(widest bore @top)
#1 - 3.3859

#2 - 3.3869

#3 - 3.3869

#4 - 3.3859

Those are the widest points near the top of the bore, and they all get smaller on the way down...
It was done a while back In prep for a future build, I'm not sure why they tapered it, other than
they never had any pistons to work with.

Now I have a set of 2g pistons 86mm over, piston skirts coated with PC-9 by swaintech

-Stock size- Swaintech Coated

A- 3.3845 - 3.3878

B- 3.3846 - 3.3869

C- 3.3844 - 3.3867

D- 3.3841 - 3.3860

The reccomended PTW from Swaintech is the tight end of Mitsubishi Specs measured after coating is applied
so somewhere in the .0010-.0015 range

I Probly confused the crap out of everyone, But does anyone with any Machine shop XP think this would be workable
seems like it might as long as the rebore does not remove more than .001 out of the top third of the cly?



 

rdomeck

Well-known member
Joined
Jun 1, 2011
Messages
620
Location
Indianapolis, In.
Seems like your numbers are right on. It depends how picky you want to get. I little tapper isn't a horrible thing. If you think about what .002" is compared to the over all length of the cylinder it's not bad. I used to set Porsche engines up with a little bit of tapper...Maybe .0005-.001" I recently built my VR4 engine and I would have to check, but I think it had .0008 taper on two of the cylinder's. I didn't feel that little bit would justify boring an otherwise perfectly good stock bore block!

Depends if your building a street car or a very competitive track car?

As I tell my employee's....Don't let perfection get in the way of good enough!
 

alansupra94

Well-known member
Joined
Mar 3, 2010
Messages
1,909
Location
Wayne,NJ
sh*t man, let me pull up all my numbers when I get home but looks like you are on the right track.
 
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