340 Balancer ? Forged Crank?

[EDDO4570]

OK here goes, I am almost ready to put the pan on the 340 . I know it has a forged steel crank in it. As I am clearing out the empty boxes of parts my brother in law ordered for this thing, I notice that the summit Harmonic ballancer he ordered PN # SUM-163273 says 273-360 Int. Balance Nodular Iron Crankshaft Damper.... Does this mean that it is for CAST cranks or just the material it is made of. I dont want to fire this motor and have it jump out of the mounts.

Thanks in advance,
 EDDO

[Moparal]

You answered your own question...For internal balanced engines from 273 cube to 360.  Look at it on the summit site. You will see the info...go for it. But most engine balancers want the flex plate/flywheel and balancer you would be useing. Still all in all, it will or should be balance zero and ready to go

[EDDO4570]

 Thanks Moparal,
   I dont think there will be any problems, If so, I can still switch it out after i drop it in anyway.{just more work}. Ill find out this weekend.
   Thx again,
Eddo

[71chally416]

Make sure your torque convertor (if it's auto?) doesn't have balance weights on it. If it was a smog 340 or any 360 previously in the car, it will have offset balance weights on the convertor too. If it does you'll have to cut them off or you'll have a vibration. If it's a stick they drill the offest weight into the flywheel so you'll need a different flywheel   

[Chryco Psycho]

the balancer is wrong or a steel crank engine like yours

[EDDO4570]

Got a fresh look at it this morning. I am pulling the aftermarket balancer off. The crank looks to have been balanced at some point in its life ,by looking at the different color of the lightening holes in the crank wieghts . This was obviously a balanced unit.Thanks everyone.

[71chally416]

That would indicate that it's been "Internally balanced".

If it was "Extenally balanced" they add counterweights to both the dampner and convertor or flywheel, like they have on 73 340's and all stock 360's. I've never seen in my life a forged crank motor that was extrernally balanced. You have the right balancer in that box.

[EDDO4570]

Ok Chally , I will leave it on, but if your wrong ,I get a 2 second Handicap on race day

[71chally416]

I'll give you two seconds even if I'm right, as long as I can use slicks 

[71chally416]

Can you post a pic of the engine side of your torque convertor and your flex plate if it isn't a stock one?

[EDDO4570]

The motor was originaly a 4spd setup. The guy I bought the engine from kept the flywheel. I am putting on a flexplate from a 1978 318 and a 3000 Hughs stall convertor. There are no wieght lugs welded on either pieces. Everything seems like it will bolt up without any hassles. I told the broth in law that he should have got a SFI flex plate because of the higher stall but he didnt want to spend the extra $ 

Eddo

[71chally416]

You're good to go! Shouldn't have any vibration problems. I just wanted to see if there were any balance weights on the convertor or flexplate. I'd use some removable locktite on all the bolts. Shouldn't need a special flexplate unless you have some monster motor. It's plenty strong.

[EDDO4570]

Great !!! Should be in and running tommorow if UPS shows up with the headers.
 Thanks a bunch Chally

[71chally416]

Anytime. I've already made every mistake twice! 

[Moparal]

With you installing a 3k converter, I would opt in buying an sfi solid flex plate. They are not expensive and you will be happy knowing pieces wont come through the floor boards if that little one breaks apart. They can crack easy under power.