390/360/352 what's the difference?

[mikeconner1]

I've been told that the 390, 360, & 352 engines share the same block (352) and heads, and are completely interchangeable. I've also been told that the difference is in the stroke, or connecting rod length, with the longer rod increasing the CID of the engine. From this I would extrapolate that if one had any of these engines, and would like to make either the 352 or 360 into a 390, changing the rod length is all that's necessary. I ask this because I have a tired 390 that I'd like to replace, but I don't want to down the truck while I'm building the new engine, and I have both a 352 & a 360, but not another 390. What's the real scoop, is this correct, or a lot of rot?

[fordman]

to make a 390 out of a 360 you need the crank and the rods. plus you should change the pistons because fo skirt and wrist pin location. to make a 352 into a 390 you do the same thing. i think if you want to make a 352 into a 360 you change eithe just the rods or is it just the crank.

[My427stang]

Displacement comes from bore and stroke

Think of the term "displace"

At the top of the stroke there is a certain about on room, at the bottom of the stroke, there is an open cylinder with a certain amount of room. That toal area is the displacement of a cylinder. Multiply it by 8, and you get the size of the motor

Make the bore bigger, that "cylinder" displaces more room, OR make the stroke longer, and that cylinder also displaces more area.

So with that being said:

A 352 is a 4.00 inch bore, 3.50 stroke

A 360 has a bigger bore at 4.05 inches, but the same stroke as the 352

A 390 uses the bigger bore of a 360, PLUS the added stroke of 3.78 inches.

Connecting rods do change based on dimensional requirements, but the connecting rods dont change displacement.

The crankshaft determines the stroke (distance the piston goes up and down), and the bore is how big the cylinder and pistons are.

The last comment is, most every FE, barring 427s, use a casting that SAYS 352 on the front, that doesnt make it the same motor.

[FORD428CJ]

Sorry Ross but the 360 and 390 share the same bore. Here they are and good luck. Happy Thanks Giving to ya!!!!!

FE engine displacements Displacement Bore Stroke
CI----Bore-------------------Stroke
332 4.000 in (101.6 mm) 3.300 in (83.8 mm)
352 4.002 in (101.7 mm) 3.500 in (88.9 mm)
360 4.052 in (102.8 mm) 3.500 in (88.9 mm)
361 4.047 in (102.8 mm) 3.500 in (88.9 mm)
390 4.052 in (102.9 mm) 3.784 in (96.1 mm)
391 4.052 in (102.9 mm) 3.784 in (96.1 mm)
406 4.130 in (104.9 mm) 3.784 in (96.1 mm)
410 4.054 in (103.0 mm) 3.98 in (101.1 mm)
427 4.232 in (107.5 mm) 3.784 in (96.1 mm)
428 4.132 in (105.0 mm) 3.98 in (101.1 mm)

[My427stang]

Read mine again and apologize Wes

I said the 360 has a bigger bore than a 352

The 390 has the bigger bore of the 360 PLUS longer stroke...

I was comparing both motors against the 352.

Stop questioning your field graders in public you know we are never wrong

[fastEdsel]

[fordman]

you have to be in the right mood to eat that stuff. pass the salt.

[FORD428CJ]

Sorry Ross, I did miss read your post. My bad on that!!! I dont know what I was thinking at the time Bro.

[My427stang]

Move it on guys, no show to see here

Wes and I know each other, and are both Air Force, so I was teasing more than anything.

[fordman]

i am watching to hell and back abotu audie murphy in wwII. and they were singing a song to make the flyboys mad. it went up in the air jr birdmen flying high in the sky. birdmen thats funny.

[DuckRyder]

[Clears Throat]

Could we get back on topic?

[/Clears Throat]

A 360 is easy to convert to a 390, the block is the same, you need only a 390 rotating assembly.

The 352 block will usually bore safely to a standard 390 bore, but not a 390 over bore.

[FORD428CJ]

Move it on guys, no show to see here

Wes and I know each other, and are both Air Force, so I was teasing more than anything.

True that!!! LOL Teasing is good for the soul and same with the Air Force.

I'll get back on track here. You can make a 410 if you like. Same Bore (360/390) and throw in a 3.98 (410/428) crank and whamo. More CI with the same block!!! Good luck.

[mikeconner1]

Thanks for the expertise guys. Based on what I'm reading, it appears that my best bet would be to have my parts ready, snatch out that 390 and get it to the machine shop, and put it back together with the same engine instead of trying to cobble together something from my extra 360 & 352. The 68 Effie that this 390 is in is a real pleasure to drive since I installed an Edelbrock carb & intake last winter to replace the old stock cast iron 2BBl setup. But she's got burnt valves on #4, and just smokes too much to suit me. It runs so good wore slap out I can't wait to put in a fresh 390, probably end up with several tickets cuz if it'll run, I'm gonna mash on it. Just have to drive the '60 or the '56 until its done. Thanks again.

[willowbilly3]

Remember you need a 65 or newer (year model) block to have the bosses cast in for truck motormounts.