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PKRWUD · 12-02-2001, 07:29 AM

Okay, let's start at the beginning. The 1979 and older 5.0's had a heavy crankshaft. Since the 5.0 is an externally balanced engine, this meant that the counter weights could be small. They placed a 28 ounce counterweight on the flywheel and the balancer to make up for any internal imbalance. The 5.0's built from 1982 on had a lighter crankshaft, which meant there was a greater imbalance, which required larger counterweights on the balancer and the flywheel. Specifically, they placed a 34 ounce weight on the balancer, and a 50 ounce weight on the flywheel. For stock applications, these must remain as they were originally, meaning 1982 and later 5.0's need to have the 50 ounce set (34 ounce balancer and 50 ounce flywheel), and 1979 and earlier 5.0's must retain the 28 ounce set (28 ounce balancer and 28 ounce flywheel).

Now, once the engine becomes modified, things can change. If your engine is an '82-'84, and you installed Forged pistons, or if you install a forged crank for any year 5.0, you will have increased the internal weight enough to justify using the 28 ounce set. If you were to have an engine built, and had it balanced, you could have it done so that you could use the 28 ounce set as opposed to the 50 ounce set, which would put less stress on the crank.

I don't know what the story is on your engine. I read the beginning of this thread where you mentioned installing a 28 ounce flywheel, and I wanted to make sure you knew that your balancer had to be 28 ounces as well. If your engine is a stock '95, you should use a 50 ounce set. If your engine has been modified, then you need to contact the builder and ask them which set you should use. When the choice is yours, before any parts have been purchased, less is always better. In otherwords, if your internal mass weighs enough to justify a 28 ounce set, then by all means, use one. But if it is basically a stock rotating assembly, then a 50 ounce set would be better.

The single most important thing to remember is to have a matched set. A 28 ounce flywheel and a 34 ounce balancer will cause a bad vibration immediately, and will cause damage to the bearings initially, and the journals eventually, not to mention the damage done to the rest of the engine due to the unbalanced vibrations. Also, to avoid confusion, forget that the 50 ounce set balancer actually weighs 34 ounces. Refer to them as either 28 ounce sets (28 ounce flywheel and balancer) or a 50 ounce set (50 ounce flywheel and balancer). Otherwise, you'll drive the parts man crazy.

Take care,
-Chris

12-02-2001, 07:29 AM	#7
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Okay, let's start at the beginning. The 1979 and older 5.0's had a heavy crankshaft. Since the 5.0 is an externally balanced engine, this meant that the counter weights could be small. They placed a 28 ounce counterweight on the flywheel and the balancer to make up for any internal imbalance. The 5.0's built from 1982 on had a lighter crankshaft, which meant there was a greater imbalance, which required larger counterweights on the balancer and the flywheel. Specifically, they placed a 34 ounce weight on the balancer, and a 50 ounce weight on the flywheel. For stock applications, these must remain as they were originally, meaning 1982 and later 5.0's need to have the 50 ounce set (34 ounce balancer and 50 ounce flywheel), and 1979 and earlier 5.0's must retain the 28 ounce set (28 ounce balancer and 28 ounce flywheel). Now, once the engine becomes modified, things can change. If your engine is an '82-'84, and you installed Forged pistons, or if you install a forged crank for any year 5.0, you will have increased the internal weight enough to justify using the 28 ounce set. If you were to have an engine built, and had it balanced, you could have it done so that you could use the 28 ounce set as opposed to the 50 ounce set, which would put less stress on the crank. I don't know what the story is on your engine. I read the beginning of this thread where you mentioned installing a 28 ounce flywheel, and I wanted to make sure you knew that your balancer had to be 28 ounces as well. If your engine is a stock '95, you should use a 50 ounce set. If your engine has been modified, then you need to contact the builder and ask them which set you should use. When the choice is yours, before any parts have been purchased, less is always better. In otherwords, if your internal mass weighs enough to justify a 28 ounce set, then by all means, use one. But if it is basically a stock rotating assembly, then a 50 ounce set would be better. The single most important thing to remember is to have a matched set. A 28 ounce flywheel and a 34 ounce balancer will cause a bad vibration immediately, and will cause damage to the bearings initially, and the journals eventually, not to mention the damage done to the rest of the engine due to the unbalanced vibrations. Also, to avoid confusion, forget that the 50 ounce set balancer actually weighs 34 ounces. Refer to them as either 28 ounce sets (28 ounce flywheel and balancer) or a 50 ounce set (50 ounce flywheel and balancer). Otherwise, you'll drive the parts man crazy. Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!