I just pulled an early 70's 360 from my panel truck. I am replacing it with a rebuilt 390. Problem is... i rebuilt the 390 2 years ago and have forgot wich bottom pulley to use. The 360 had a harmonic balanced pulley. The pulley I have for the 390(I think it goes to it) does not have the balance weight on it. I think 390 to be around 1976 or so. The one on the right is 360 and the one on the left is what I think goes to the 390.

 

Double post

 

Both the 360 and 390 are internally balanced. The only externally balanced FE's are the 410 (Mercury only) and the 428. Those use an external balance on the flywheel. The 428 SCJ uses an external balancer at the front too.
The harmonic balancer you want to use is the one on the right. That's the same one my '73 390 has. The one on the left looks to be passenger car maybe.

 

Does that particular balancer type have the rubber sandwich between the steel outer weight and the cast part?

I cheaped out at the end of my F100 engine rebuild years ago and reinstalled a junkbox damper, and that caused me a fair amount of grief. The timing marks were way, way off for one thing. Jus' sayin', if this is the case a rebuilt engine, really deserves a fresh balancer.

 

Thanks for the info. I am pretty sure the 390 came from a later 70's truck. According to the previous owner. The 360 I found in a junk yard for a 100 bucks with the t-18 tranny. I know nothing about it, just it smokes more than my aunt Ethel. As for rubber in between, I don't see rubber. Looks to be bolted solid.

 

My 69, 428cj also uses the one on the right. Since I'm the original owner I know that it's the correct one.

 

Now you got me wondering if the 360 is a 360. Maybe I should pull the pan and make sure it's not a something else. It makes me wonder since someone took the time to pull this engine and it smokes pretty bad. Maybe it's not a runofthemill 360.

 

Check everything

I once took a rebuilt 360 out of my highboy that my brother rebuilt. He swears it was the original factory motor that he rebuilt.

"Knowing" that a 390 and a 360 are both internally balanced, I reused that flywheel to build a 390, and after I got it all together and in the truck, I started it up to find I had a REALLY BAD vibration.

Turned out, the flywheel had the big ugly weight on it for an FT. By this time, the 360 crank I had was gone to the crank grinder's for a core, so I never went back and found out exactly WTF was going on.

But somehow, that 360 that my brother redid turned out to have an externally balanced flywheel. Again, it was factory - he bought the truck brand-new and KNEW it was what it was.

How the heck a 361FT crank wound up in that truck, who knows. But it was real.

Moral of this story: CHECK EVERYTHING. Never assume.

 

I was planning on using the"360" flywheel along with the front pulley. I should be good then...right?

 

After 40+ years the rubber in those harmonic balancer dampers is unable to function as originally designed. Get a new one and enjoy extended life of bearings and crank.

 

Not an authority, perhaps by posting the crank pulleys' casting #'s a more knowledgeable member than I am can narrow it down, when all is done the pulleys; crank, as well as accessories, should be a match set?

 

Here's a good primer on FE crankshafts from DIY Ford: Ultimate Ford FE Engine Crankshaft Guide