The Ford Barn

Kevin in NJ · 09-04-2017, 06:57 AM

Will not hurt if done right.

Before he touches your crank ask who grinds the cranks and to what specs. He should know the factory print specs and work to them. Does he check the work on a surface plate.
I know this sounds like a lot but this is critical to get done right. Some consider .002" acceptable for the flywheel off center, some dont. We have a crank ground with the flywheel center at .008".
Contrary to what some might tell you, crank grinders can mess up your crank in ways you might not expect. Unless you have access to a surface plate you may never know there are problems. From centerlines on the mains not being on center to each throw not having the same throw. Add in the critical getting the flywheel on center line and you have a lot of things a grinder needs to keep to thou accuracy. If the shop does not think that is needed then you best go elsewhere if you want a car that will run 50,000 miles on a rebuild (the babbitt should last that long).

Then ask what he does for the rods. If he does not weight match each end as well as total weight then counter balancing the crank is a waste of time cause you will have a potential larger problem with the rods taking everything out of balance. Ford spec was +-1 gram at each end. A set of rods and pistons were within 4 grams in the engine when the car came off the line.

In the end, it is not about all these additions, but about getting the job done right.
The extra $700 spent on counter balancing is a waste if the system is not in tight balance and well done.

09-04-2017, 06:57 AM	#2
Kevin in NJ Senior Member Join Date: May 2010 Location: South East NJ Posts: 3,398	Re: Balancing a crankshaft thoughts? Will not hurt if done right. Before he touches your crank ask who grinds the cranks and to what specs. He should know the factory print specs and work to them. Does he check the work on a surface plate. I know this sounds like a lot but this is critical to get done right. Some consider .002" acceptable for the flywheel off center, some dont. We have a crank ground with the flywheel center at .008". Contrary to what some might tell you, crank grinders can mess up your crank in ways you might not expect. Unless you have access to a surface plate you may never know there are problems. From centerlines on the mains not being on center to each throw not having the same throw. Add in the critical getting the flywheel on center line and you have a lot of things a grinder needs to keep to thou accuracy. If the shop does not think that is needed then you best go elsewhere if you want a car that will run 50,000 miles on a rebuild (the babbitt should last that long). Then ask what he does for the rods. If he does not weight match each end as well as total weight then counter balancing the crank is a waste of time cause you will have a potential larger problem with the rods taking everything out of balance. Ford spec was +-1 gram at each end. A set of rods and pistons were within 4 grams in the engine when the car came off the line. In the end, it is not about all these additions, but about getting the job done right. The extra $700 spent on counter balancing is a waste if the system is not in tight balance and well done.