Engine balancing

[flathead4rd]

Are flathead's Internally or Externally balanced? How is each one done? Can you use either process on a flathead?

[Ronnie]

Internal

http://www.eaglerod.com/index.php?op...d=27&Itemid=25

R

[Ol' Ron]

The Flathead is internaly balanced and the factory does a pretty good job of it. Very few people re balance the engine with just a piston swap. However if using a different crank and/or rods as well as pistons I recomend you have it balanced. Most shops donot have the fixturing to balance the rods and grind the bottoms, That's a no no.

[flathead4rd]

Thanks Ronnie and Ol' Ron for that information.

[sanborn]

I agree with what Ron said----the factory did a very good job of balancing.

But, I recently bought a set of Egge pistons to replace the original set of pistons in my 276" Merc. The new pistons/pins were 55 grams lighter than the original pieces---I was very surprised.

So, I rebalanced the assembly----/

[sanborn]

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As a point of interest, the bob weight on my 276" merc was 1520 grams.

My son just weighed his hemi components and came up with a bob weight of 2785 grams. The hemi has Arias fuel pistons, Howards aluminum fuel rods, etc. A BUNCH OF DIFFERENCE!

[Ol' Ron]

The differaance in weight of the pistons, is a non issue if the rds and crank have been balanced. There are several formulas for recripcrating and rotating weights and even the professionals will tell you, unless your running a high RPM race car not to worry. Infacr there isn't an engine builder in the US that balances rebuilt engines

[Rand]

A nother? How do balance a flywheel and pressure plate on or off the car?
Randy

[cmbrucew]

Randy

I believe you do it off of the car.
Just carry it in to the machine shop.

Bruce

Works good
Lasts long time

[sanborn]

Ron, why did you want to "burst my bubble". I know the piston weight doesn't make much difference----but I wanted to do it anyway----because it's my engine and probably the last one I will do. Lighter pistons just adds to the "overbalance".

[Ol' Ron]

there is nothing wrong with having an engine balanced, it probably will increase the life expency. However, the cost of building these engines has gone up to where fewer people are willing to spend the extra money on a flathead tha doesn't produce more than 150 hp in its warmest sense. There are dozens of things you can do to increase the cost, but have very little affect on cost or reliability. Just remember this in 1956 you could bu a rebuilt Fkkathead from sears for 135 dollars and 40 bucks to install it. Probaably a few still running.

[mikebishop]

Originally Posted by Ol' Ron

The Flathead is internaly balanced and the factory does a pretty good job of it. Very few people re balance the engine with just a piston swap. However if using a different crank and/or rods as well as pistons I recomend you have it balanced. Most shops donot have the fixturing to balance the rods and grind the bottoms, That's a no no.

Ron -- Are you talking about a "Shadowgraph" scale? Ed Binggeli showed me how to match and balance connecting rods on the one in Vern Tardel's shop a bunch of years ago. What a hoot! Before this, I'd weight-matched sets of rods using a simple balance scale which does nothing other than ensure that the rods all weigh the same, without regard for the dynamic balance of having them all weigh the same plus have their big ends match one another as well as their small ends. I spent about 4 hours matching and balancing my first set, 8BAs that were first straightened, resized, rebushed, mag'd. There was lots of learning involved, and I still have them waiting for that special motor.

Mike

[Ol' Ron]

Mike, it's good to hear from you, it's been a while. I'm old fashion when it comes to these engines, they were designed with the best of the 20's offered in engineering and that lasted for 21 years and it still preforms well enough to cruise the interstates at 70 mph with little modification. However technology has tried to put it into a class with other 10 and 20,000 dollar engines. You just can't make a silk purse out of a sows ear. But they sure are pretty an no other engine sounds as good

[49r]

I thought my NOS 81A motor was pretty smooth until I had an 8BA built up and had it balanced from crank pulley to clutch. One of the best rebuild items you can spend money on IMO.

[russcc]

Balancing, depends on the intended use & crankshaft. The current Bonneville record holder for flathead roadster class is externally balanced because of the non-stock crankshaft.