[ScoTFrenzel]

Woodz

The Cj had a zero damper. So the front end of the crank had zero balance and the rear had the flywheel weight?
When the heavy rods were added, the front had the hatchet weight added.
Did an additional weight get added to the flywheel/flexplate too to make it SCJ?

It must have since adding to only one end of the crank would surely be a mess.
I have balanced a lot of engines, just trying to learn more about these FEs while this subject is open.

Thanks again
ScoT

[woodz428]

Originally Posted by ScoTFrenzel

Woodz

The Cj had a zero damper. So the front end of the crank had zero balance and the rear had the flywheel weight?
When the heavy rods were added, the front had the hatchet weight added.
Did an additional weight get added to the flywheel/flexplate too to make it SCJ?

It must have since adding to only one end of the crank would surely be a mess.
I have balanced a lot of engines, just trying to learn more about these FEs while this subject is open.

Thanks again
ScoT

The flywheel for the SCJ has the same weight as the CJ, some even share the same #. The hatchet weight is a compensation for the extra weight of the capscrew rods. It doesn't make any difference which end the weight is added, as I mentioned earlier all the small blocks have weighted dampers. The hatchet weight is basically the difference between the regular CJ rods and the capscrew rods. Once again it is a calculated balance for production, which all production engines use. That's why I always have the assembly professionally spun and balanced, factory margins are O.K. but can leave a lot to be desired in an HP engine that you want to live and run smoothly. That is even more important when you assemble an engine from a collection of parts from different sources.

[ScoTFrenzel]

Originally Posted by woodz428

The flywheel for the SCJ has the same weight as the CJ, some even share the same #. The hatchet weight is a compensation for the extra weight of the capscrew rods. It doesn't make any difference which end the weight is added, as I mentioned earlier all the small blocks have weighted dampers. The hatchet weight is basically the difference between the regular CJ rods and the capscrew rods. Once again it is a calculated balance for production, which all production engines use. That's why I always have the assembly professionally spun and balanced, factory margins are O.K. but can leave a lot to be desired in an HP engine that you want to live and run smoothly. That is even more important when you assemble an engine from a collection of parts from different sources.

Thanks again.
Back in the 90s I balanced lots of engines, never an SCJ.
Striving for mere grams of balance on each end of the crank and considering overbalance on precision race engines, a hatchet on one end seems very haphazard, indeed.
I wish I could experiment and see how far out putting a hatchet on only one end makes the crank.

[woodz428]

The hatchet weight is ,of course, keyed to the crank in synch with a throw. I would have to check the weight amount, but I imagine you could balance a regular CJ with just the hatchet weight and not a weighted flywheel...but it seems like a waste of time and energy. The late 460s also use a similar hatchet weight and I think that they have the same crank snout dimensions. Even when I have a CJ balanced I always use the weighted flywheel. I could have it balanced with out, but heavy metal is pricey as is the labor involved. The aftermarket FE flywheels are the same for all of them and have threaded holes that you attach the extra weight to. That way they only make one flywheel ( for the most common) and include bolt on weight for the 410/428s. I am not sure about the new stroker cranks, but imagine that they use an external weight as well.

[Mr. Wormy]

This is all i could find on crank, i looked for numbers on every crank counter weight, the pics might help thanks Wormy

[woodz428]

In the 5th pic, the throw right behind the 4th main should have it on one of the flats. You will need to rotate the crank and make it visible. I'll see if I can't post a pic of a couple that are in the shop, for reference.

[woodz428]

Been on here a long time, but never posted pics into a post, this is my first attempt. If it works you should see 3pics. One is the #7 428 cheek and number although the number may not be clearly visible, a #3 390 cheek and #( same possiblity of clarity as the first) and a side by side of a 390 crank and a 428 showing the difference in the #4 cheek. The 428 has some extra metal in the area.

[kj6ko]

ok, lets get simple...
FLYWHEEL, FLYWHEEL, FLYWHEEL!!

Check the flywheel for a chunk of metal welded to it on one side of the outer edge near the starter gear about 1/2" wide by about 5" long and 1/4" thick. It will be obvious!! 428 crank has it, all others do not. It will NOT have been changed unless MAJOR internal rebalancing was done! I know from experience that you CANNOT put a standard 390 flywheel/flexplate on a 428 and not have the car vibrate across the shop floor with the brake on!! It is a VERY violent vibration! Again, I know this from experience!!! I transplanted a 428 from a 67 'Bird into a 64 'bird and kept the 64's flexplate so it would match the starter. I didn't know about the balance thing at the time....I found out quick!

The front damper on my 410 has NO external balancing. Same as a 390. The original flexplate was cracked, so the machine shop took a standard 390 plate and welded a weight to it to match the original one. Runs smooth!

Also, my 410 casting # is also C6ME-A, so like the others said, it means nothing. 410 block is identical to 390. It is just a 390 with a 428 crank and was only avail in 66-67 Mercury's.