I did search and discovered this topic can be very confusing but I didn't find the answer to my question.I hope I can word this so a simple yes or no answer can be provided.I have an eagle "internal balanced" 1pc. Rms 383 rotating assembly.I know I need a zero balance flex plate, is the factory flex plate from a 1pc rms considered zero balance even though it has a weight attached.or is the only true zero balance flex plate going to be an aftermarket part.Thanks for your help.
Mark

 

No; more likely, you need a STOCK BALANCED flex plate. Which has that last little bit of INTERNAL balance weight that used to be part of the crank flange before 86, mounted in a place that makes it look "external" to the untrained and inexperienced eye. It's STILL "internal", no matter where it's mounted.

Zero balance, or neutral balance, is NOT what a 1-pc RMS motor gets.

Avoid all that "internal" and "zero" and all that other confusing and misleading terminology. The operative concept to keep focused on is STOCK. One simple word. Stick with that, and life will be good. Like, if you decide to change flex plates, you can buy one at the store and put it on, and IT WILL WORK; unlike ANY OTHER POSSIBLE COMBO.

 

Ok, so my take away from this is that the stock 1pc. rms flexplate is not neutral balance and would not be correct for ths application. Thanks sofakingdom

 

No... I think you missed the point.

The point is:

"Internal balance" DOES NOT mean the same thing as "neutral balance".

A STOCK 1-pc RMS flex plate, with the rearmost INTERNAL balance weight mounted on it and therefore NOT "neutral" balanced, most likely IS correct for this application.

Think about it: the balance weight is on the flex plate because it has to be behind the rearmost rod journal. The reason it's on the flex plate in the first place, is because it used to be part of the flywheel flange, but when they made that round so that a lip seal would slide over it, it could no longer have that funky "pork chop" shape, which is actually the rearmost INTERNAL balance weight. So they moved the INTERNAL rear balance weight to the flywheel. Just because the weight is mounted on the flex plate, DOES NOT make it "external". Now: what about this proposed aftermarket crank, allows that balance weight to be somewhere rearward of the #7-#8 rod journal? Where do you suppose it would be? If you can't think of such a place, there's GOOD REASON. The only way to do that, is with $$$$heavy metal$$$$ slugs in the crank. If they DIDN'T do that, then it still needs the rear balance weight.

Capisce?

 

Got it, I guess I was thinking that eagle has some how internally balanced their assembly's differently from the factory internally balanced assembly because of what I read on their web site."Internally balanced requires flexplate with no weights or neutral flywheel. Suitable for use up to 500 horsepower". Now that I have my answer, for someone who may be searching in the future, is it correct to say that the weight on the stock flexplate is not to balance the flexplate but is part of the internal balance of the rotating assembly?

 

The weight on the OE flexplate is to balance the rotating assembly. On a question of this importance, I would suggest calling Eagle and asking someone there directly to clarify. I'm not sure how they balanced the one pc RMS crank without the flex plate weight but knowing them, they figured out a way.

 

I just hung up from speaking to Brian at eagle specialties, he told me that their internal balanced ***'y are just that, completely balanced internal and no need for any kind of a weighted flexplate (or dampner). The factory internal balanced need to have the weighted flex plate because factory cranks don't have heavy enough counter weights to balance completely internally. I have never compared a factory crank to an eagle crank, but according to Brian the counter weights on an eagle crank are larger than factory. I hope this helps someone in the future.

 

Well consider me corrected then. I would never have thought that they would do that.

Likewise, that they would have built their product such that a stock flex plate won't work.

Good to hear that Brian is still there though...

 

Well I'm glad you know this fella Brian, it gives me confidence in his knowledge and the info that he gave me.
Thanks for your time and replies.

 

No kidding... someone remind me to never use one of those cranks.

 

Keep in mind that my conversation was regarding their internal balanced 1pc. Rms kit only.Not sure about their other kits.

 

Yeah I knew Brian from where he worked before Eagle. From probably 15 yrs ago or more. Then later, he lived in a little neighborhood right in front of where my late little bro had a condo. Great guy.

It's a REAL small world.

But yeah I'm SUPER bummed that they set their cranks up to where stock stuff won't work. I haven't ever used a 1-pc one of theirs so I didn't know that, and it surprises me greatly. That doesn't make sense. I wonder if they'll do a "normal" one on special order.

 

Luckily McLeod make a off the shelf internal balance 1 pce flywheel for anybody running a stick car with this crank
http://www.summitracing.com/parts/MCL-460350/
http://www.summitracing.com/search/P...I/?Ns=Rank|Asc