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DougG 
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Joined: 20 Sep 2009
Location: Mo
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 Topic: AC 301+426 engine balancing
Posted: 05 Jan 2014 at 7:17am |
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When putting a steel flywheel on a 301 or 426 AC engine are they internally balanced or externally balanced? What does that mean? How does a machine shop balance a crank , flywheel+ clutch?Is it worth it?
Edited by DougG - 05 Jan 2014 at 7:20am
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Tim-tn
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Joined: 15 Sep 2009
Location: West Point ,TN
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Posted: 05 Jan 2014 at 7:58am |
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Doug the 301 and 426 are internally balanced, if an engine is externally balanced the flywheel and balancer have the weight added to them. As far as is balancing off the crankshaft, rods and pistons necessary it would depend on the rpm's you want to turn, for sure it does not hurt, I run a 210 with a 426 and it has been balanced, I run 3000 rpm class.
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Tim-tn
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Posted: 05 Jan 2014 at 8:16am |
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Machine shops balance by weight, they make all pistons weigh the same, as well as the rods and match with the crank, machine shops around here tell me there is no need to worry about flywheel/clutch.
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tbran
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Location: Paris Tn
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Posted: 05 Jan 2014 at 5:19pm |
FIRST the machine shop weighs each piston finding the lightest one , then the others are drilled to remove the weight necessary for all to match. Then each rod is weighed big end and small end on a special scale and the same process employed. The rods have balance pads on them for grinding off material top and bottom. Now this weight of rod, piston assembly is attached as a bob weight to each throw on the crank which is spun and balanced as one would balance a tire. Cranks are either drilled or heavy metal slugs added to compensate for weight.
I have heard engine builders discuss balancing and disagree on the need. Our experience started in 78 when we started having 7080 engines breaking cranks.
The reasons were many - most poor quality control out of Harvey is my diagnostic. \We found bad viscous dampeners, loose front pulleys, probably bad metal in cranks, bad timing - too advanced - AND after ordering a rod and measuring it just fof kicks , terrible balancing. We tood a motor to Tuckers at Murray Ky and then Jerry Don was helping us diagnose the failures. He measured a rod and said he had never seen so much weight difference on an engine. I told him AC bragged about precision engine balance of components. He showed me a finished engine he had for me. It looked like a drill and chop saw demonstration site. I reported this to AC - they would not warranty the balancing but did allow us to warranty a rod - claiming out of balance and not making us return it.... the field guys way of fixing a problem . Anyway when we returned the engines to the owners over a 4 year period each owner noticed and reported "it sounds and feels like a different tractor" We never had another issue with the engines we rebuilt, some are still running. We did also check the timing, backing off a degree, and the advance of the RM pumps - some were off advancing way too soon, as the aforementioned front pulley and balancer. ( Never had a flywheel issue except for my stint in Jeanerette La where one of the mechanics decided to cure torque limiter slip by bolting a piece of metal to the flywheel to prevent the pad from slipping by - I lie not - I was ask to go down and see why all the 7000 were falling apart... I actually have a picture somewhere. When I ask "did you not know this would throw the engine out of balance/" " Ah I gonna told ya they say balance don't no matter on low rpm diesels"
SO does it matter? I guess peace of mind that something is done right has some psychological therapeutic value....
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DougG
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Posted: 08 Jan 2014 at 12:02pm |
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Dang sounds like Harvey was loosly operated ?? How could they hide that from corporate, after all it was their money and AC ,s reputation
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tbran
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Posted: 08 Jan 2014 at 8:40pm |
run the engines out the door, mail the invoices, cut prices to get contracts like Barko loaders and stick it to AC tractors division to try to make up the difference . When the volume drops get the forklift division to put AC engines in and thus the margin goes down and the price goes up and sales drop on forklifts. There were super people at Harvey but when times got tuff they could not compete with the Case/Cummins CDS , Deere and Perkins. Too low production unit sales, too high a unit cost.
Yes quality did suffer at times but trying to hold costs down.... it always bites you...
the solution is to have the sales #'s like Deere and Perkins - it just didn't happen.
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DougG
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Posted: 09 Jan 2014 at 8:00am |
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That was a shame AC had good engines, in my opinion, i have a magazine of when they built the new Harvey Plant and they were so reved up on the new engine lines coming in gonna build mass amounts and up to 1000 hp,, they had good intentions!
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tbran
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Posted: 09 Jan 2014 at 8:14pm |
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WE WERE MUCH BETTER ENGINEERS and fixers THAN SALES PEOPLE - salesmen beat engineers every day at getting the $$$$
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DougG
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Posted: 10 Jan 2014 at 4:32am |
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That seems so true AC was an excellent engineering dept
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