The CCC’s have run into a slight stumper on sledgehammer’s new 406. It concerns engine balancing; internal as opposed to external.
If my little bit of research is correct, an internally balanced engine is one which has all the piston/rod assemblies machined to within 1 gm of each other. Is the crank then dynamically balanced resulting in a neutral balanced engine? Dose that require a neutral balanced flywheel?
External balancing, if I read correctly, is done with a harmonic balancer and flywheel that is matched to the engine.
Are the balancer and flywheel different for an internal balanced engine as opposed to an external balanced one?
And finally, are the 427 and 454 BB’s different in regards to balancing??

Thanks in advance for clearing up something that is a mini mystery to me.

:confused: :D

 

Dunno about the BB's but the 400 engine is balanced with the flywheel and harmonic balancer. They are different than the 327/350 engines. You can (and should) have a 400 sbc engine balanced internally IMO. It keeps the cost down because you can use 'neutral' balancers/flywheels off your old engine.

 

Here's the deal:
The 400 and 454 Chevys are externally balanced from the factory. This means they have a crankshaft that requires a counterweighted balancer and a counterweighted flywheel (or flexplate) to offset the balance of the crankshaft itself. All of the internal engine pieces, like the rods, pistons, etc. are still individually balanced, but the crank balance must be offset through the use of the counterweighted balancer and flywheel. Likewise, a "383" engine, which is a 350 with a 400 crank in it, is usually externally balanced, using the 400 pieces on the ends of the crank.

The 350, 396 and 427 engines are all internally balanced, meaning that the crank is neutral balanced, and the flywheel and balancer are not counterweighted. It is possible to internally balance a 400 (or 406), but it is VERY expensive to install the heavy metal into the crankshaft to obtain the neutral balance. It is possible to procure an internally balanced crank for a 400, but these run about $1200-$1500. Some people claim that the internally balanced engines will last longer, but that's certainly up for debate...

The externally balanced 400 (406) is the way to go for an economical high performance street engine. The weighted components are the standard 400 parts, and they are readily available in stock and high performance versions. The internal moving parts are still balanced individually for a precise balance job and a smooth-running high performance engine.


[Modified by lars, 3:31 PM 1/7/2003]

 

Hi Dave!
You and I must have been posting at the same time - I didn't see your post until mine was up... I see you favor the internal.. have you priced it out lately to have heavy metal installed in a crank? At least here in the Denver area, the balance shops are getting a lot of $$ for doing this - more than the cost of the counterweighted balancer and flywheel, so I've been going the external balance route on the 400-based stuff I've been building - it works really well. But I certainly respect your opinion - have you found an economical way of neutral-balancing a 400 crank?


[Modified by lars, 3:47 PM 1/7/2003]

 

Hi Lars, nope no cheap way of doing it that I know of. Just another opinion and opinions are like noses, you know....everybody has one. :lol: I'm a shade-tree guy so I would personally go externally balanced. He just asked the difference really so I prolly shouldn't-a added an opinion. But, I couldn't help it.........I'm so smart. :jester :blueangel:

 

Aw, man, Dave - you definitely gotta add your opinion..! :yesnod: And I see that the results of the balance opinion are as follows:

Master Shadetree: External Balance
Master Drunk: External Balance

Hey John - you need any more opinions than that?? :jester

 

Thanks Lars for succinctly clearing that up. My mind can now go on to other things. :chevy :chevy :chevy

 

You guys are the best - thanks for all your behind-the-scenes efforts on the new engine.

So, I just ordered a new Hays flywheel that specifically states that it is for an "externally balanced 400 SBC". Along with the harmonic damper that ships w/ the engine, is there anything else I'll need in this regard?

Also, I should mention -- in addition to the Hays SBC 400 flywheel, I have the following related parts on the way:

Centerforce Dual-friction Clutch Kit - 11" kit - 1 1/8 x 10 spline
Summit Roller Pilot Bearing
Lakewood Adjustable Clutch Fork Pivot Ball
GM Large Bellhousing - casting #621 that will accomodate the 11" flywheel/clutch

Anything else to add, anyone?




[Modified by CO_Sledgehammer, 4:47 PM 1/7/2003]

 

Beer and whiskey, we will probably need some stinky old salted fish for Lars to munch on as well.
Also make sure to bring a carpenters hammer for the photos, bluetripe67 really likes this. :yesnod:

Thats all I can think of for now, but if I remember anything else I will let you know.

Kurt :cheers: :steering:

 

Another oddball is the post-'85 one-piece rear seal center-bolt 350's; they use an external-balance flywheel, and a neutral-balance damper :rolleyes:

Here's a pic of the Viper V-10 crank - fully-machined forging, internally-balanced with six slugs of Mallory metal; not cheap, but bulletproof! :D



:steering:

 

Hey John (CO_Sledge) -
They did build the engine as an external-balance engine, didn't they...? You didn't have them do the expensive neutral-balancing of the crank did you? You need whatever balance type flywheel that matches the type of balance job they did to the crank. Or has the engine been built yet? The flywheel should be balanced to the crank for best results, so it would be good for the engine builder/balancer to have both the flywheel and the crank for the balance operation.

JohnZ-
Neat pics of those cranks. Yeah, that heavy metal used in the crank balancing must be made out of Gold for the price they get for it... good reason not to do the neutral-balance on an external-balance Chevy crank...

 

I know I am going to sound like a moron here but what else is new. So if the 400 crank relies on the balancer and flywheel to balance it wouldn't those two components be specific to that individual crankshaft, which would rule out mixing and matching parts.

Steve

 

Hi Steve!
In a production environment, the component parts are all built and balanced individually with a known amount of counterbalance in each of the parts. If all the counterbalanced parts are right on spec, the engine will be perfectly in balance. Obviously, there is a tolerance on this balance and counterbalance spec, so it's possible to achieve a situation that is less than perfect. The same applies to a neutral-balanced engine with its neutral-balanced parts. Production-type replacement parts, such as an aftermarket counterbalanced flywheel, will meet or exceed the tolerance spec for the counterbalance requirement, and will normally work just fine when installed on a production engine.

Custom engine builders will send all of the rotating parts out for balancing to a custom balance shop. At a custom shop, every part is first balanced individually (each rod is balanced for total weight as well as end-to-end weight, for example), and then the rotating parts are balanced together (the crank with the balancer and the flywheel). This produces precision unmatched by a production engine. The parts can still be swapped out, and the engine will most likely be within the production tolerance for balance, but the precision of the custom balance job will be lost if the parts are swapped around.

 

Thanks Lars. You know, you sound almost rational at times, those new meds must really be doing the trick. Have the nice men in the white coats brought you your jello yet?

Steve

 

Jello and Valium. Mellows me right out. It's when they release me at the end of the day and I go home to Valium and Beer that things start going whack-o.....

 

Sledgehammer,

Am I correct in assuming your car had a 10.5" clutch and your going to a 11" ?? Is the 11" stronger??

Thanks :cheers:


[Modified by hogan64, 4:09 PM 1/8/2003]

 

Lars,

The builder did say the engine is an externally balanced type. I'm going to talk to my builder today to see if I can send him the flywheel.

Hogan64,
I am going from a stock-type '64 clutch to an 11" setup. I believe the stock size is 10.4" or 10.5". I'm not sure if it's stronger or not, but the 11" disc is the one listed by Centerforce for this application.

 

John
Good - sounds like you have all the right pieces all matched up. If the engine is already built, there's no point in sending out the flywheel - he will have balanced the engine both piece-part and as an assembly, and the balance tolerance will be very good. Your aftermarket flywheel will also have a very precise balance to it, so the flywheel and engine will mate up together very well - no problem.

Hogan64 -
The larger diameter clutch has more friction area than the smaller clutch, so it is capable of handling more torque. The big advantage of the 400 over the 350, of course, is the longer stroke, which produces more torque. This is the reason the big blocks all used the 11" clutch. On this subject, note that driveline components "see" only torque - the don't "see" horsepower. Clutches, transmissions, driveshafts and rear ends are designed around torque limitations.

 

Well, John and Lars. I think I will jump in with some expert insight at this point....

I think that "M22 Rock Crusher Stout - Brew of the CCC" will definitely be a brew in demand in 2003. Its got character and sophistication; a real head on its shoulders; its definitely friendly; and it is well balanced internally and externally.... need more be said??!

:cheers:

********************

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Jeff
‘66. Modified L72
“The Silver Beast”
Keep on :cheers: :seeya :steering: :thumbs: