I was wondering what it would take to convert a 360 engine to a 390. From what i understand, they are almost the exact same engine except for the 390 has a crankshaft with a longer throw. So i am assuming that all i would have to do is swap out the crank and maybe install a deeper oil pan and possibly a different oil pump. Is this correct????? Any information would be helpful. Thanks.

 

All you need to change is the crank, rods and sometimes the pistons. You don't need a deeper oilpan ( unless you just want to increase the oil capacity) or different oil pump.

 

How will i know if i need the replace the pistons or not? The ones in it now are in good shape and have all new rings.

 

If they're 360 pistons and in good shape, you dont need to replace 'em. They'll boost your compression ratio on in the 390. Make sure you use 390 rods with 'em or they'll be above deck.

 

Thanks for the info but i have one more question. Do you know what the compression ratio will be if i use the 360 pistons with the 390 crank and rods?

 

It depends. What heads are you using, how many cc's are the valve pockets on the pistons, and what is the thickness of the head gasket?

 

Everything on the heads has been rebuilt but they are still stock as well as the head gaskets.

 

Do you have a casting number off the heads? It should be between the center two spark plugs. That will allow me to determine what the stock cc's are.

 

What are the different combustion chamber sizes used on FE's? Specifically, on 360's?

 

The different sizes are 67-70cc on the D2 and later heads, and 70-74cc on earlier heads. It does make a difference somewhat.

 

It will definitely make a difference in the ratio.

I ask because I just got my engine back from the shop. It's a 360 from a '71. I had it bored .030 over and 390 crank and rods installed.

I'm a little concerned because the shop put 360 pistons in it, thinking I would want the extra compression. It basically has zero deck clearance. Now I'm sure I'll have to run premium gas, and wondering if that will be enough.

 

You should be ok. The FE's aren't prone to pinging even with 10:1 compression, due to head design.

 

With the right cam, it will run on even 87 octane with 10.25 to 1 compression, my 68 Merc's 390 does.

 

Well, that's good news. Of course, according to another thread I read on here, my cam is the worst thing ever put in a Ford engine.....

 

What cam was that?