Adding 428 counter weight to 390 FLEXPLATE- balancing

[Rory428]

Is it a 1 piece or 2 piece flaxplate? I have had some 428s from 1966 that had a 2 piece flwxplate, which was heavier than the more common 1 piece unit. I have only owned 1 410, from a 67 Mercury, and it had a spoked 1 piece flexplate, with a welded on counterweight, that looked the same as the 428 flexplates I have.

[GJCAT427]

Nope its a one piece. It looks just like a 390 solid, but it has the counter weight. I`ll see if I can post a picture this week.

[My427stang]

This is a Ford one out of a 410

[GJCAT427]

Exactly what I have, But with the separate bolt reinforcement ring.

[dozz302]

That's interesting-I've never seen one of these. That is definitely factory-I can tell by the welds- same as the CJ flywheel I have. I guess the 410 just used a 390 flywheel and put the counter weight on. As far as one breaking I have seen one out of a bracket car years ago that completely broke free in the spoke area where the big holes are- probably had a lot of runs on it. I was in a  1969 must. running 11.50's.

[GJCAT427]

my427stang, question for you, does your 410 crankshaft have the standard 428 markings on it? I got to cleaning mine up and found a stacked YJ on it. No other marks so far. This motor has been punched to .060 so the block is more or less junk. It supposed to be 10/10 according to some stampings but the bearings are not marked as such. Still needs more cleaning before I measure it . This YJ has me scratching my head.

[My427stang]

I got that one off of a propane irrigation 428, and it had junkyard yellow marker "410" written on it, so no idea what it came off of.

Never saw the YJ marking though

[GJCAT427]

My427stang, after some cleaning I found the crank # 1U. It has a small counter weight on the middle main cheek. Don't remember see that before. Anybody have picts of the 428 variations of those cranks?

[cammerfe]

Ford calls the automatic transmission 'flexplate' a flywheel. I believe 'flexplate' is GM terminology.

That said, when we received one of the first dozen CJ Mustangs, we built the transmission for it at T&C Livonia. We used a 390 flywheel, to which the ring gear is 'electron-beam-welded'. Our first outing with the new parts was to the drag strip across the river in Windsor. On the first pass, the starter came loose from the C6 at about the 60' mark. We replaced it and on the second pass the same thing happened. This time the starter pocket in the case was ruined and the case split back at the crown section.

On tear-down we discovered that the counterweight was welded to the flywheel 180 degrees out of place. (In our quest to have it right, it was a carefully-done hand job---just not in the right place.) OOPS!!!

KS

[wayne]

Jegs sell a steel flywheel  with a bolt on weight hays makes it. I am older then dirt and its a long time ago when we  raced what has  changed back then we got the heaviest flywheel we could get.Now everyone runs the super lite stuff.

[jayb]

My427stang, after some cleaning I found the crank # 1U. It has a small counter weight on the middle main cheek. Don't remember see that before. Anybody have picts of the 428 variations of those cranks?

All the 1U and 1UB cranks have that little counterweight.  The 1UA cranks don't, so they are the SCJ cranks and are worth more.  Go to 428cobrajet.org for some good pictures of the crank differences.