Can someone clear this up for me? When I go to look for pistons they list them 68 and up 390 and some are 360/390. How are the the older 390 pistons diffrent, my engines a 64. Maybe a silly question but I cant find the answer. Thanks
I think you're seeing 1968 as kind of a "starting" year since that is when Ford went to the 360, with the same bore as a 390, and started using existing pistons from one combination to juggle compression ratios in another engine combination - like using the higher compression 390 car pistons in a pickup 360, or the higher compression 410 pistons in a pickup 390, to lower compression. I looked in an old TRW catalog ( back when many of the older FE's still had replacement pistons available ) that I have and there are a couple different common compression heights listed, mostly 1.680" & 1.775", so it is something you will have to watch if you are trying to use an existing piston in a different application, but it's not specifically a 1968 thing. I think you see off the shelf replacement pistons still more readily available for the later FE's just because Ford made so many millions of those trucks, and so many are still around. Many people doing a stock rebuild, especially on a old work truck, don't care about taking advantage of the better piston technology available now. For the smaller group of people working on a FE in an old classic, like you are, they can take advantage of a modern piston with, say a thinner ring pack, and a lighter piston, than just using a copy of the old stock piston. After this 50-60 years now too, there are just too many variables, even for someone doing a "stock" rebuild, for the piston companies and part stores to carry an off the shelf piston - blocks have been milled, cylinder heads have been cut, head gaskets have changed, the original early cast iron cylinder heads may have been replaced by a later version, or even by an aftermarket aluminum replacement, and so on, that the engine builder needs to take that all into consideration in picking a piston, and the piston company doesn't want to tell you that something will "fit". Just my guess on the subject, sorry if that was too rambling lol.
