On Fri, 19 Sep 1997 23:02:31 -0700 TheMole <dbilesky(at)cln.etc.bc.ca>
writes:
>If I was to go oversize from std and locate an OEM flathead piston
>then I need the dimensions of the originals.
>
>I would like to bore to some standard oversize dimension.
>
>I am thinking that the OEM product, of which I am open to suggestions,
>maybe longer (or shorter) in which case I would have to compensate on
>the
>length of the piston rod.
>
>----
>
>Also, if I hipo'd the alpine engine should I think about the drive
>train
>too. Not necessarly replacement but an upgrade of somesort. It has an
>OD.
>
>What about the cam shaft?
>doug
It is my understanding that flat top pistons with correct dimensions
can be ordered, and Curt Mienel has told me before that he can get them.
This should not alter anything beyond the net compression ratio as the
flat tops are likely some 1725 derivitive for a high volume cast iron
head hillman motor.
That combo will net you better than 11/1, which is likely more than
your gasoline wallet will tolerate.
If its performance you are after, the iron or chrom rings used on the
1592 and 1725 motors + the the cast aluminum pistons are not
up to the task of running those compression ratios.
If you are in performance mode, consider having some pistons made
at it doesnt cost too much more than stock pistons, and the performance
advantage is significant due to higher strength, lower weight better
rings
ect.
The concerns toward MAKING a piston are as follows...
1) You must know compression hieght.
This is the distance from the tip of the crown to the centerline
of the grudgeon pin.
2) You must know the grudgeon diameter.
3) You must know proper bore size based upon the availability
of rings for the given bore range.
4) You must know the length of the original pistons.
If you are going to use other than stock rods, you must compensate
by shifting the compression height, and likely the grudgeon pin diam.
Jarrid Gross
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