Balancing rotating assembly questions???
Thread Starter
Drifting
Joined: May 2004
Posts: 1,904
Likes: 2
From: London(UK)/Troyes(France)
Balancing rotating assembly questions???
Hi guys,
I have been reading on how to balance a rotating assembly. It said everywhere how important it is to weigh the rods and pistons and then balance te crankshaft.
Let's say you want to forge your 346. You get a set of forged pistons and rods with new rings and bearings, wristpins... and you want to keep your stock crank and block.
You remove the motor from the car get the block bored and honed with torque plates and now come the balacing part.
- Do you have to remove the crankshaft from the motor to balance it as well?
- Or is getting each rods/pistons combo to weigh the same enough? Then you just install them and that's it.
I am looking into buying some Diamond forged pistons and Callies rods and just forge the motor myself. What do you guys think?
I had several vendors in mind but thos that I really trusted don't seem to care about my business so I guess I'll try it alone
Any advice will be very appreciated! I will do H/C on top of my blower this summer and if I see that I can handle the piston/rods swap, then I'll go for it as well.
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I have been reading on how to balance a rotating assembly. It said everywhere how important it is to weigh the rods and pistons and then balance te crankshaft.
Let's say you want to forge your 346. You get a set of forged pistons and rods with new rings and bearings, wristpins... and you want to keep your stock crank and block.
You remove the motor from the car get the block bored and honed with torque plates and now come the balacing part.
- Do you have to remove the crankshaft from the motor to balance it as well?
- Or is getting each rods/pistons combo to weigh the same enough? Then you just install them and that's it.
I am looking into buying some Diamond forged pistons and Callies rods and just forge the motor myself. What do you guys think?
I had several vendors in mind but thos that I really trusted don't seem to care about my business so I guess I'll try it alone
Any advice will be very appreciated! I will do H/C on top of my blower this summer and if I see that I can handle the piston/rods swap, then I'll go for it as well. .
Safety Car
Joined: Jul 2005
Posts: 4,275
Likes: 4
From: Vancouver WA
The crankshaft has counterweights to counterweight the weight of the piston and rod assembly. So yes, it should be rebalanced as an assembly. If you can find some rods and pistons that are the same weight, then you wouldn't. But the rods would have to weigh the same on each on, not just total weight. Plus, I doubt that the factory balance is as precise as what a machine shop could do. (As long as they know what they are doing) If you are going to go thru that much work, might as well do it all the right way.
You will have to remove the crank anyway to do any block work. IF I may suggest, if you are doing the assembly yourself, do this.
Deck the block square.
Align hone the mains
Bore and hone to the next size (Using Torque plates for honing)
Install new cam bearings, and bring the cam you are using to the machine shop so they can fit the bearings to the cam.
Check the crank for straightness, and polish it. (Regrind to .010"/ .010" if necassary)
Chamfer oil holes in the crank
And if you are going make some serious power, it would be a good time to install some steel main caps.
You will have to remove the crank anyway to do any block work. IF I may suggest, if you are doing the assembly yourself, do this.
Deck the block square.
Align hone the mains
Bore and hone to the next size (Using Torque plates for honing)
Install new cam bearings, and bring the cam you are using to the machine shop so they can fit the bearings to the cam.
Check the crank for straightness, and polish it. (Regrind to .010"/ .010" if necassary)
Chamfer oil holes in the crank
And if you are going make some serious power, it would be a good time to install some steel main caps.
Last edited by RED99; May 20, 2007 at 10:25 PM.
Thread Starter
Drifting
Joined: May 2004
Posts: 1,904
Likes: 2
From: London(UK)/Troyes(France)
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