Howdy all. So in the process of my first engine rebuild, replacing everything but the crank, and rods. Found out after looking at crank, that i have a 360, and not a 390. My question is
Can i use a 390 rebuild kit in a 360? Everywhere i look, the 390 kit is like $200 or so cheaper for the same parts. Do the piston pins match? Pistons height the same on aftermarket pistons? I know factory was different, but i am hearing aftermarket pistons all work. Also a new crank and rods to make a 390 is most definitely out of reach right now, due to already blowing budget. Thanks!

 

I don’t know why the price would be different since it should be the same kit

 

You'll hate life if you put "regular fuel" 390 pistons in a 360.

6-ish:1 compression isn't fun.

Now, 360 pistons (390 4V) in a 390 is the only way to fly for a "stock" 390 rebuild.

A couple years ago I threw together a Ford 360 using Dodge 340 pistons and ended up with a nearly 9.5:1 360. Still running great to this day. Strong runner!

 

Google's AI gives a pretty good answer if you search: "FE 390 vs 360 pin height" AI will report the pin heights, and rod lengths are different. If I was you, I would stick with a kit meant for a 360 or as mentioned, you will have unintended low compression, that will run sub-par compared to dialing in the compression and squish, depending on the head chamber size and piston's design.For the amount of time to pull out, tear apart, machine, and rebuild, it's not worth the $200 savings for the extra hassle. A decent set of pistons will set you back. If you are cost constrained, plan on 20% contingency on the extra items, like replacement fluids, cleaning supplies, additional tools, and all the stuff you find along the way that you didn't think of that "while I'm at it" tends to creep in.

I would assume the lower price just reflects market conditions of supply and demand. Maybe there's just that much more 390 interest than 360; making the 360 stuff harder to come by (lower inventories).

If you're caught up in the performance end of things, you can always look at a new intake and headers to help her breath- easy external bolt-ons that can be re-used on a 390, if you decide in the future to build a 390. Honestly though, the cost of the crank, rods, and pistons IS the price to pay for the upgrade and in the grand scheme of engine building, not a huge increase in overall project cost if you stick with a cast crank and pistons; you'll kick yourself later for not spending the extra $$, if you can- always wondering if the 390 upgrade would have been a better choice; not saying the extra cubes do all that much, but it will be in your head, psychologically speaking.

 

You need to look at the compression height of the included pistons. Look up the p/n of the piston and find the specs; You want a 1.76 compression height (i.e. 1131 piston). The cheaper kit usually has a 1.66 compression height (i.e. 1139 piston). You also need to figure out what your compression is going to roughly wind up, regardless of which piston you end up with. Some of these pistons really get it up there.

I'd avoid Google AI for anything but a starting point. It makes stuff up and is NOT always accurate. It has burned me many times.

I see that this is an old thread, but that's my $.02.