Stroker rebuild

Carl · Post by **Carl** » Sat Jun 07, 14 2:12 pm

Yep the very one Dunc. It should now be 8 thou PTW clearance. As Les recommended.

Cannonball · Post by **Cannonball** » Sat Jun 07, 14 3:15 pm

Carl wrote:Yep the very one Dunc. It should now be 8 thou PTW clearance. As Les recommended.

is this not excessive les ?????? i thought 4.5 -5 what make pistons are they, do some forged grow more than others ???

mopar_mark · Post by **mopar_mark** » Sat Jun 07, 14 10:44 pm

Cannonball wrote:
Carl wrote:Yep the very one Dunc. It should now be 8 thou PTW clearance. As Les recommended.
is this not excessive les ?????? i thought 4.5 -5 what make pistons are they, do some forged grow more than others ???

Duncan,
It's 0.008" on Diameter, which equates to .004" clearance

Mick70RR · Post by **Mick70RR** » Sun Jun 08, 14 10:34 pm

You sure about that Mark?
I thought piston to wall clearance is the difference between the piston skirt diameter and the cylinder diameter.
0.008" sounds too much to me, 0.004" sounds about right for a forged piston in a small block.

latil · Post by **latil** » Sun Jun 08, 14 10:38 pm

I was always taught 1 thou clearance per inch of bore 4 thou is about right.

mopar_mark · Post by **mopar_mark** » Mon Jun 09, 14 12:11 am

Mick70RR wrote:You sure about that Mark?
I thought piston to wall clearance is the difference between the piston skirt diameter and the cylinder diameter.
0.008" sounds too much to me, 0.004" sounds about right for a forged piston in a small block.

As I understand the bore diameter is now 0.008" bigger than the Piston skirt diameter. Therefore the clearance is 0.004"

Mick70RR · Post by **Mick70RR** » Mon Jun 09, 14 10:33 am

mopar_mark wrote:
Mick70RR wrote:You sure about that Mark?
I thought piston to wall clearance is the difference between the piston skirt diameter and the cylinder diameter.
0.008" sounds too much to me, 0.004" sounds about right for a forged piston in a small block.
As I understand the bore diameter is now 0.008" bigger than the Piston skirt diameter. Therefore the clearance is 0.004"

I'd say the clearance is 0.008".

Dave-R · Post by **Dave-R** » Mon Jun 09, 14 11:09 am

Mick70RR wrote:
mopar_mark wrote:
Mick70RR wrote:You sure about that Mark?
I thought piston to wall clearance is the difference between the piston skirt diameter and the cylinder diameter.
0.008" sounds too much to me, 0.004" sounds about right for a forged piston in a small block.
As I understand the bore diameter is now 0.008" bigger than the Piston skirt diameter. Therefore the clearance is 0.004"
I'd say the clearance is 0.008".

I would too....

Carl · Post by **Carl** » Mon Jun 09, 14 11:16 am

Well its 0.008 now so cant do anything about it now whether its right or wrong.

Dave-R · Post by **Dave-R** » Mon Jun 09, 14 11:20 am

Confused?

Carl · Post by **Carl** » Mon Jun 09, 14 11:24 am

Dave wrote:Confused?

Yep

Im sure Les will clarify

Steve · Post by **Steve** » Mon Jun 09, 14 11:28 am

Am I right in assuming that if the piston was perfectly centred in the bore, a 0.008 thou clearance would mean you could, in theory, run a 0.004 feeler gauge all round the piston. If the piston was pushed flush against the bore...180 deg opposite point where it touches would take a 0.008 gauge??

Carl · Post by **Carl** » Mon Jun 09, 14 11:35 am

Yep that's about the size of it Steve

Steve · Post by **Steve** » Mon Jun 09, 14 11:40 am

Gotcha....just trying to learn from your thread Carl as its really interesting....

so the discussion at the moment is whether you should be able to run a 0.004" gauge round or a 0.002" gauge?? Sorry if its a daft question mate but Im watching your build closely and want to stay with the plot....

Dave-R · Post by **Dave-R** » Mon Jun 09, 14 11:46 am

Steve wrote:Gotcha....just trying to learn from your thread Carl as its really interesting....

so the discussion at the moment is whether you should be able to run a 0.004" gauge round or a 0.002" gauge?? Sorry if its a daft question mate but Im watching your build closely and want to stay with the plot....

And that clearence depends on the piston material. Forged pistons expand more. High silicon forgings less so. And cast pistons less again. I would be wanting 4 thou each side so a 8 though wider bore.