Hey guys
I'm sure this was covered somewhere, but my search netted 0 results. I'm going from a t-18 to a C6 on a '73 460 motor. When did the 460 go from being internally balanced to externally balanced, and what was the balance weight? I need to know what flexplate to pick up, and EBay has 2 different ones, an internally and externally balanced flexplate. Thanks!

 

Since you have a 73 motor it is internally balanced. Around 79ish the engine became externally balanced. You can tell by the hatched shaped harmonic balancer spacer vise the completely round spacer on internally balanced engines.

 

So I'll need a flexplate with no counterweights, right, since it is internally balanced?

 

Yep thats what I have on my 75 460.

 

Thanks a bunch. Ya'll are lifesavers.

 

And yes it was 79 and up 460's that were externally balanced.

 

Alright, bot the tranny home and got the flexplate and all associated hardware, and was hooking it up last night. Discovered that the flexplate I had wouldn't fit inside the bellhousing of the C-6 I got from a 79 Bronco. What gives? How many different kinds of flexplates were used on the 460? I know it was too big because the torque convertor studs all lined up with the holes but everything else was too big. I know a 390 flexplate will also fit on a 460. Is it possible my buddy gave me a 390 flexplate instead of a 460 flexplate, hence the non-fitness in the tranny? That's the only thing I can think of right now...

 

What motor did the Bronco have in it?

 

It had a 351M/400. As far as I knew, the transmission is the same between the 351M/400/429/460. The flexplate, however, was found in a stack that he had. It's got the 460 bolt pattern and no weights on it, so it had to be for an internally balanced motor. Are there different diameters for flexplates for 460's?

 

You are correct about the trans.

I couldn't tell you about the flexplate.

 

Heck, maybe I'm just lining it up wrong or something. But I even had the torque convertor studs lined up and everything! I'll have to mess with it some more...

 

Just something i thought about, Did you take out the old pilot bushing in back of the crank
GWB

 

Yea, I discovered that as soon as I attempted to size the torque convertor the first time. I always wondered what the pilot bushing was, and now I know.
Now, the flexplate. The 460 flexplate is ~14 1/4 inches in dimeter. The flexplate I have is 15 1/2 inches in diameter. I have no idea what this was from. My friend, who gave me all the essential parts, had no idea what this flexplate came from, and he's been dealing with Ford trucks for 25 years+. It has the 460 bolt pattern (390 also, I suppose), and the torque convertor studs line up perfectly. Maybe this one is off some heavy truck version of the 460-C-6 persuasion, with a larger bellhousing C-6? Maybe it's for a 352/360/390-C-6 combination? We obviously can't use this flywheel, so I went ahead and bought another one off EBay, but we are stumped as to what application this flexplate is for. Like I said, 15 1/2 inches across, no counterweights, 460 crank bolt pattern.