[AJD] 620 Piston question

[Dean VP]

I did some work on a couple spare 620 aluminum pistons today and was a bit
surprised that they didn't completely match. One piston has the casting
number A5555R (inside the skirt) which is the STD sized JD piston for 620's
and 630 gas tractors. It also has 620 G stamped on the piston top. All as
expected.

Then the surprise came. The second piston does not have a casting number,
looks like the other one except no casting number and has 630 G stamped on
the top of the piston. 

Now I'm aware the 620G and 630G pistons are the same but can anyone explain
the differences I have noted?  

Both pistons have been knurled on the skirts opposite the pins. I assume
that has been done during an overhaul at some time as I don't think they
come from the factory that way. On first blush they don't look all that worn
and ring lands look pretty good to me. It's been a long time since I have
seen a set of new 620 pistons, if ever. :-)

Also, I'm taking two 620 blocks into a machinist tomorrow for Magnaflux and
dimensional checks.  Any one able to point me to a manual or document that
gives the specs on the pistons and cylinders? Or have those handy? 

Thanks for any and all help in advance. 

Dean A. Van Peursem
Snohomish, WA 98290

I'm a walking storeroom of facts..... I've just lost the key to the
storeroom door 


www.deerelegacy.com

http://members.cox.net/classicweb/email.htm