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EFV-8 Club Forum / General Ford Discussion / Do engines need to be balanced

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Posted By Discussion Topic: Do engines need to be balanced     CharlieStephens 10-15-2009 @ 11:44 AM reply profile send p.m. Senior Posts: 888 Joined: Oct 2009 Chris, When you balance an engine you (probably the shop you hire to do the work) go through and weigh each moving part and then grind or machine off or weld on weight. When you finish all of the pistons weigh the same (how close they are to the same depends on how much money you spend). You balance each end of the rods separately. You balance the counterweights on the crankshaft. When something rotates like the flywheel clutch and pressure plate you must add or remove weight based on how far the weight is from the center of rotation (a good analogy is balancing the tires on your car). If you are really thorough you balance the crankshaft pulley. I wouldn't build an engine without having it balanced. Charlie Stephens supereal 10-15-2009 @ 10:02 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 At our shop, we balance all engines that we rebuild as a part of the complete job. Each piston and rod assembly is weighed, and a "bob weight" with an equal amount is placed on the rod journal. The crankshaft is then spun as a gauge measures for any out of balance condition. A drill press mounted on the machine is used to modify the counterweights until the vibration disappears. Any off balance of a rotating part will likely show up as a periodic vibration in a completed engine. Some require little adjustment, while others really shake. Be sure to ask the place offering engine rebuilding if they include balancing. If they say it isn't necessary, I'd look elsewhere. trjford8 10-15-2009 @ 7:59 AM reply profile send p.m. Senior Posts: 4214 Joined: Oct 2009 It's not that much more monney to balance a motor. I had two flatheads balanced and the both ran so much smoother it was well worth the money.Make sure they balance the flywheel and pressure plate as a unit. 47Fordor 10-15-2009 @ 4:15 AM reply profile send p.m. Member Posts: 72 Joined: Oct 2009 Forgive my ignorance: I'm just getting into the engine rebuild game. What exactly are you referring to when you say "ballance"? Chris 51f1 10-15-2009 @ 3:31 AM reply profile send p.m. Senior Posts: 573 Joined: Oct 2009 No, it doesn't have to be balanced. However, I had my 8RT balanced, and it runs extremely smooth. I wouldn't rebuild an engine w/o having it balanced. Richard This message was edited by 51f1 on 10-15-09 @ 3:35 AM ford38v8 10-14-2009 @ 10:06 PM reply profile send p.m. Senior Posts: 2758 Joined: Oct 2009 I'm kinda far afield here, as I'm not a machinist nor an engine builder, but I'm going to wing it: Engine balancing is a relative term, which applies to several different operations. A crankshaft can be balanced by means of drilling on the heavy side of the counterweights. Flywheels in much the same way, but with clutch mounted. an altogether different type of balancing is done with the piston/rod assembly, in which piston/rod assemblies are matched by weight in pairs. This is a careful mating of similarly weighted parts, involving only a scale and patience. these mated pairs are then mounted to offset each other's weight in the spinning engine, thus eliminating excessive vibration. I believe that any good re-builder would not consider assembling an engine without performing this operation. Alan CharlieStephens 10-14-2009 @ 4:35 PM reply profile send p.m. Senior Posts: 888 Joined: Oct 2009 I had the 21 stud in my '37 balanced. The shop said it was way off but I didn't run it before. When it was finished it was one of the smoothest early Ford motors I have ever had and I assume that balancing was the reason. Charlie Stephens MOXIE 10-14-2009 @ 4:00 PM reply profile send p.m. New Member Posts: 102 Joined: Oct 2009 I’m trying to decide if I should spend the extra bucks to have my 21-stud engine balance. I remember 10 years ago I had a small block Chevy engine balanced and I could not tell a dime’s worth of difference. Do most of you balance.

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