Balancing an engine - necessary or not?

tubman

tubman

Well-known member
I think I've hi-jacked the "Green Mercury" thread enough, so I thought I'd start a new one because I have a few more thoughts. From what I've read here and experienced in my own life, I think ending up with an "in-balance" engine after a rebuild is a matter of luck. Your chances are much better with the more original components you retain, because it seems the manufacturers do a pretty good job when they build them. With a simple "ring 'n valve" job, balancing is almost certainly unnecessary. On a stroker with crank and rods from different manufacturers, you better feel pretty lucky to skip the balancing step.

About 30 years ago, I met a guy at a car show, We both really liked each other from the start, and started comparing cars. He had a '50 tudor, while I had my '51 club coupe. After chatting a while, he said that he noticed my engine ran noticeably smoother than his. This was kind of irritating to him, as his had been freshly rebuilt (without balancing) the previous year, while mine was bone stock from the factory. After a discussion or two, we decided that one weekend we should try to figure out what was going on. In the final analysis, we checked his compression, which was consistent between all cylinders and within spec. We then swapped my carburetor onto his car, and even moved my distributor and coil over. We could never get the problem to move. We decided that it was probably an engine balance issue, and he decided he would live with it, because it was hardly noticeable. It never bothered him before he saw both engines running at the same time. After all this time, I'm not sure I even noticed it, but it bugged him. Maybe he was one on the unlucky ones.
 
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When you install new pistons, rings, take the plugs out in the crank and clean it out. Tap and install new plugs in the crank.
Today you do not know to what speck things are made.
Yes I would balance it.
 
To keep the answer short and to the point, if the owner avoids the balancing operation and there's an issue it's "on them", if a shop does the build and there's an issue it's on the builder.

I would also add balancing in itself is NO money-maker. It is time-consuming and usually cuts in to the other shop profits. Drilling on these "cast" Flathead cranks (actually on any cast shafts) is easy, you'd need to try drilling some 1.000" holes x 1.000" deep in many of the aftermarket "4340" cranks. You WILL go through some drill bits, believe me. Try to imagine the time spent drilling those size holes! The cranks are almost as hard as the drill bits you're using!

It gets even worse when you need to ADD to the c'weights, rare on any Flathead but not so rare on many conventional V-8's. A piece of 1.000" x 1.000" heavy-metal (tungsten) runs about $50.00/per. Many shafts need 4 or 6 pieces, this is WITHOUT the labor.

Thanks, Gary in N.Y.

P.S. Owning a pair of balancers (2) I cannot risk NOT balancing the rotators. I would add this, simply changing a set of pistons that may vary +/- 20 grams with 100% stock Flathead rods/crank would most likely pose no issues. That's a 40 gram spread overall.
 
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I had all of my 59L's guts balanced, including the clutch and flywheel. Consequently, it runs as smooth as plate glass, I can even balance a nickle on edge on top of the oil-filter housing bolt while it's running. For the refinement and piece of mind it was worth the extra $175 I paid for this service.
 
Not balancing an engine is like buying cheap house paint. I would never build an engine without having it balanced.

Charlie Stephens
 
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Additionally have the flywheel neutral balanced. Then balance the pressure plate separately. They will mark both so you can assemble it correctly. That way down the road if you need to replace the pressure plate, the new one can be balanced and should not cause any problems.
 
I took all the parts to a rebuilder I had used for decades. He had someone else balance the parts. All were rendered unusable. After getting a new set of Pistons,rods and crank, I took them to a shop that builds racing engines. They ground the small end of the rods almost to the pins. I got another set of rods and went to another shop. The parts returned were still usable but I have had perfectly stock flatheads that were smoother. At this point, I would not balance a flathead. They don't turn high rpm's and the parts were in balance stock. I found that flathead rods were sorted by weight. If you mix up rods, you may end up with a problem. Try to keep a set of rods together. A digital scale is your friend.
Just my experience. Others have more than me for sure but I went thru hell with the balancing.
 
I have had 2 engines balanced. They were both smooth runners, but like the previous poster I remember being sort of shocked about where they ground on the rods and how haphazzard they looked. I have built some smooth runners here in my cluttered little shop too. This subject could be as exhausting as a motor oil thread. I'm just glad we all get to do it just the way we want and hope we all have a good time building and driving them.
 
Well I guess this is mostly my fault. In the past, back in the late 50's early 60's, there wasn't many engine balancers around. Bell's in Patterson NJ was the closes to me. At the time the cost was around 80 dollars, but took several months to get the parts back. I remember one of themen there telling me it wasn't necessary. Racing at Danbury there were about 70 flatheads, one Buick, one Chevy 5, and one Caddy. To my knowledge veryy few were balanced. I'm sure the big money racers did balance their engines. Working out of a shop in Bidgeport Ct (Bill Barths), Very few of his engines were balanced sa well untill on day he said the the SBC was one of the poorest balanced engine around and began having them balanced someplace in NY. I was going to have ours balanced but the owner refused to pay for it. by this time it costs around 100 bucks.The reason he said was: With all those engines running at Danbury howmany blow up? The answer very few. I mean in 8 years time I don't remember only a few and one was caused by a flywheel.
Later, when I started Nostalgia engines I offered balancing as an option, by now the cost was up to 150 or more and I found out that the rods were balanced wrong. It was at that time I was keeping the rod sets together and in corporated the street balance. Most piston sets are balanced, the rods are factory selected . so just giving the balancer one cylinder set to make bob weights. Could balance the assy for much less money. Remember then as well as now the Small block chevy was only a brand new running engine for less than 2 grand and the junkyards were full of them for just a few bucks. I was getting around 2500 for a 276 complete. Not many people loved flathead that much. I think My Book helped get more people interested. Today the hobby is fueled with hi tech 10,000 flatheads that still can't make 200 hP but are just beautiful and sound great. I take my hat off to those that go this route, and Walt Dupont is my hero.
 
I think that it was a good thing for you to bring up, Ol' Ron. I've come away from this with a greater appreciation of what's necessary and what's not. For example, I have an engine sitting in the shop that I pulled out of a 41,000 mile wrecked '50 Ford that had been sitting in a garage since 1954. I got it running, but it had some stuck valves; the rest of the cylinders are 110-120. After I'm done with the two I'm doing now, I'm going to tear this one down, lap the valves, re-ring it, and put in new rod bearings. After this discussion, I won't feel a bit guilty about not balancing it
 
I thought my NOS 81A motor was pretty smooth until I rebuilt an 8BA and had it balanced crank pulley to clutch. A noticeable improvement. I would always balance when rebuilding an engine.
 
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