RF Flywheel, Engine Balancing

I was talking to Gordon Levy this past Saturday, and he is of the opinion that you really need to balance the engine with the RF flywheel.

I was thinking of buying an already assembled engine, and so I was wondering if anyone else out there has an opinion on the necessity of balancing the engine with the RF flywheel.

Thanks.

 

You must be carefull in your engine choice as the small block Ford engine is an externally balenced engine. The fly wheel and damper are offset weighted to accomplish this. The early engines till 80 are a 28 oz factor, from 81 0n they are 50 oz. The late models that I have worked on are pretty good for a factory balence, but any time I change any of the rotating components, even if they are factory replacements I rebalence the engine.

Vic

CAV 40
Lemans Blue
Owner built 302
Getrag trans

 

[Robert Logan]

Kevin,

Chevy engines are nutrally balanced : that is that the THREE rotating components ie. flywheel, crank rods and pistons, and finally the harmonic balancer are all balanced to ZERO. This means that the three components are interchangable and can be mounted at any angle to eachother.

The Ford engine's components are ballanced as a lot and are in essence out of balance with eachother but together they are IN balance. For this reason they are mated to eachother with woodruff keys (balancer) and offset bolts (flywheel) to ensure correct allignment.

To replace the flywheel the new flywheel must have thew same out of balance force. This can be done two ways :
1.re balance the complete rotating assembly. This requires the total striping down of the engine.
2.mirror balance the new flywheel. This is used in many Ford race teams as it does not require the engine strip. I believe it is hard to find but contact a Ford race team.

Best wishes,

Robert

 

[Dave Wharran]

Kevin,
I originally used a McLeod 157 tooth steel flywheel on my engine. 28 oz imbalance. Crank, damper, and flywheel were balanced as a set. I later found a McLeod aluminum flywheel that I couldn't pass up. Also 157 tooth, 28 oz imbalance. I had had the steel flywheel machined for 4 magnets for crank triggered/direct fired ignition. When I switched to the aluminum, I had the same machine shop also set it up for the same 4 magnets, same locations. They "mirror" balanced the aluminum flywheel to the steel and had to drill some weight out of the counterweight to make them match. My suggestion would be to have things balanced as a set. If you change anything, have the new item balanced to match the old one.

 

Thanks, everyone.

I am certainly convinced me that I must balance the engine with the new flywheel. I figured Gordon was right, and you all confirmed that.

 

[Gary Gibbs]

If you have the money and are building a motor from scratch you might consider zero balancing the motor internally. Then you add a zero balance damper and flywheel. It does not matter later if you change components as long as they are zero balance. Also the crank loads will be better as you are putting the mass closer to where it needs to be (inside the engine hopefully at the appropriate throw).

 

[Howard Jones]

OK I understand the reasons that are stated above. But If some one was to buy a SVO crate motor and use a kit builders flywheel I find it hard to believe many people take the whole thing apart and have it all rebalanced. The idea of matching the SVO flywheel ballance to the "kit" flywheel sounds a lot better. Now I'm not a engine builder so just how important is the rebalance issue? Lets say that the motor will be limmited to 6000RPMs. Is this one of those things that must be done on a race engine but isn't all that necessary on a street driven motor. I'll take it all apart if I have to but I really don't want to if the motor will be "OK on the street"

 

[Neal]

Realistically, so long as you match the damper (28 or 50oz) to the flywheel, you are likely to be OK. I suspect most production motors are "balanced by design" not dynamically. Optimally, you should balance for best performance.

 

[Ross Nicol]

Howard
I've just finished building my motor and have been through the balancing issue.I bought a mid 80's HO 5.0 block and am using the standard crank so here's what I did,
1/ fitted Romac harmonic balancer with 50oz counter weight.
2/ fitted aluminium flywheel with 50 oz counter weight.
3/supplied the balancer,flywheel and crankshaft to machine shop for balancing as a unit.
I reckon you are right Howard and the balancing is not something you get in a stock motor off the assembly line.so just fit a 50oz counter weight to your new flywheel and go for it.Of course if you go racing or run consistent high revs I would recommend you strip and balance the 3 Items above.
regards Ross

 

[Howard Jones]

My motor is a SVO 302 with the 50oz balance requirement. I put on a ford 50oz crank damper but used the GTD V6 flywheel, I'm guessing, but I would think that the flywheel isn't a 50oz type. Does anyone know? I didnt know, really I didn't think of it, about the flywheel ballance being 28oz or 50oz. I have the ford flywheel that came with the motor. Maybe I should match ballance my GTD V6 flywheel to the V8 unit that came with my motor. What do you guys think? Is this necessary right away or can I wait until I have it all apart for my planned gearbox upgrade. I expect to put 2000-3000 miles on the car before then. I can of course limmit revs to a safe number until then.

[ May 22, 2003: Message edited by: Howard Jones ]

 

[Ron Earp]

I had mine balanced as a unit when the short block was done.

But, I've never understoods Fords in that fashion. I mean, if I were designing a rotating assembly I'd design it so that each piece of the assembly had no imbalance. Am I missing something here, why would you want an imbalance?

Ron

 

[Steve Toner]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR> But, I've never understoods Fords in that fashion. I mean, if I were designing a rotating assembly I'd design it so that each piece of the assembly had no imbalance. Am I missing something here, why would you want an imbalance? <HR></BLOCKQUOTE>

Ron,

My recollection is that it allows for a smaller block. Not enough room internally to allow for a balanced crankshaft...

 

[Robert Logan]

Steve,

You are 100% correct why Ford balance externally.

As regards to "shall I do it or not" well ever tried to drive a car with an out of balance wheel. There is likely to be a resonance frequency that will set up harmonics and will shake the engine. If you are a member of the selected few from birth that are very lucky (all us Irish are included) than forget the balancing. Not even I rely on birth placement !!!!!

Always remember to take the extra five minutes to do the job corectly. Some people live their lifes thinking that you can never have enough time to finish a job but can always find the time to fix the f**k ups. Not a good idea. Just balance it , do the job correctly.

Best wishes,

Robert