Balance Factor for Standard Cord V8 Engine

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20 Jul 2018 05:19 #35014 by Terry Cockerell
Terry Cockerell created the topic: Balance Factor for Standard Cord V8 Engine
Can anybody tell me what is the correct Balance Factor for a standard Cord V8 engine.
My engine reconditioning man has not touched one of the engines before hence the request is urgent.
Thanks
Terry Cockerell
Australia

T cockerell

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20 Jul 2018 16:36 #35019 by 1748 S
1748 S replied the topic: Balance Factor for Standard Cord V8 Engine
Very good question Terry. I have often wondered about this also. My knowledge amounts to the counter balance weights MUST come off to resurface the rods and mains. There are special bolts that secure them to the crank and.. They get welded in place. So removing them is a pain. I suppose your asking how close the balance is to be. First off every rotating piece of machinery will have a critical rpm. Ever watch a large grinder coast down to zero rpm. No matter the balance it will shake for a few rpm. When I balanced my 92 indirected injection V8 diesel I prepared the pistons complete with rings on the roda with the bearings in place to less than 1/4 gram between all 8 cylinders. When my engine is running you hear it but do not feel it at all.. It has 520 lbs cranking compression too and boy does it stop turning when the ignition is turned off. Our Cord engines turn about the same rpm as my diesel does. Terry I can't tell you to balance this close but remember. the closer the rotating elements are the better the balance shot comes out. A gram scale comes in real handy for grinding and checking balance on parts. When the balance shot is done on the spinning crank they pre weigh each rod complete with everything on it. Get an average. Then make up weights that clamp to the rod bearing areas. Spin up the set and check where weight needs to be added or removed. There is mid plane balance and the ends also have a balance point too. Its an interesting mathematical calculation too.

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20 Jul 2018 23:33 - 20 Jul 2018 23:38 #35022 by Terry Cockerell
Terry Cockerell replied the topic: Balance Factor for Standard Cord V8 Engine
The key point in all of this are the temporary weights that are fitted on the big end journals. These weights are a percentage of the connecting rod and piston assembly weight hence the percentage is the Balance Factor. Without knowing what the correct weight of these items is we cannot balance the engine properly.

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Last Edit: 20 Jul 2018 23:38 by Terry Cockerell. Reason: Revising text again

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21 Jul 2018 02:12 #35024 by 1748 S
1748 S replied the topic: Balance Factor for Standard Cord V8 Engine
Terry each rod with fitted piston and rings.. As if you are installing it to run the engine.. Has to be weighed on a balance scale. Sometimes the big and small end are weighed too.. But all 8 must be very close to weighing the same for the best balance shot and a smooth running engine later on. Usually you just give the balance shop every rotating piece of the engine. They do the grinding to make everything within a specific gram weight or each other.The flywheel and damper is included in this too. Our engines do NOT have a vibration damper on them either.

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21 Jul 2018 07:33 - 21 Jul 2018 07:34 #35026 by Terry Cockerell
Terry Cockerell replied the topic: Balance Factor for Standard Cord V8 Engine
Gary I am aware of everything that you have said however the crankshaft is fitted with special bob weights to do the actual balancing work. These bob weights are usually 100 % of the conrod rotating weight plus 50 % of the conrod and piston reciprocating weight. My engine guy thinks the Cord has a different % figure for reciprocating weight. This is what I am trying to find. I will send you a You Tube film on how it is all done, the guy mentions 100 % plus 50 % for that particular engine.

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Last Edit: 21 Jul 2018 07:34 by Terry Cockerell. Reason: Text mods

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30 Jul 2018 06:27 #35103 by Terry Cockerell
Terry Cockerell replied the topic: Balance Factor for Standard Cord V8 Engine
After a lot of heart ache it turns out there is nothing special about having an 810 Cord crankshaft balanced. The weight of the piston assemblies have to be the same and the connecting rods have to have equal weight also. The crankshaft is fitted with bob weights which are equal to 100% of the rotating connecting rod weight plus 50% of the connecting rod and piston assembly reciprocating weight for fine tuning of the balancing work. It turns out that my balancing guys had made a mistake calculating the reciprocating weight. Once the error was discovered the job was able to be completed properly. It really pays to measure twice.

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The following user(s) said Thank You: Jonathan Richards, 1748 S

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