Rod and Piston weight matching

[The Kansan]

Hey guys i was curious where you would take material from on a mahle race cast piston and a crower rod to do weight matching for engine balancing? Im going to have my rotating assembly balanced soon and would like to get your opinions on that, Thanks

 

[gmduramax]

Never take material out of the piston. I believe they take it out of the wrist pin

 

[andy-stevenson]

X2 Wrist pins

 

[The Kansan]

Ok Thats what i was curious about. I thought you took it out of the inside of the wristpin but wasnt sure.

 

[S Phinney]

Materials taken off the wrist pin will have to done by a machine shop. You can't do it with hand tools yourself. They are extremely hard. Materials can be taken from the skirt if necessary. That isn't the preferred way but it is OK to do if you know what you are doing. Hopefully you are letting a qualified machine shop do the work. The right equipment is a necessity period.

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[Ne-max]

X2

Also in the rods its just not the complete rod weight. A good machine shop will match the ends.

 

[The Kansan]

Materials taken off the wrist pin will have to done by a machine shop. You can't do it with hand tools yourself. They are extremely hard. Materials can be taken from the skirt if necessary. That isn't the preferred way but it is OK to do if you know what you are doing. Hopefully you are letting a qualified machine shop do the work. The right equipment is a necessity period.

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The machine shop that is balancing everything is doing it, I was just asking bc i was curious how it was done.

 

[S Phinney]

Sad part of it is that most machine shops do not balance as close as you would expect. They may mix heavy pistons and light rods and so on. Talk in depth about that and your expectations.

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[Ne-max]

Also make sure they are using a torque plate. Most machine shops dont have them for duramax engines. I had to buy one for mine.

 

[battlegraduate09]

Sad part of it is that most machine shops do not balance as close as you would expect. They may mix heavy pistons and light rods and so on. Talk in depth about that and your expectations.

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This, some are just unqualified in general. I got a set of inline6 rods back from a local machine shop the customer chose that were junk. All weight machined off the cap, wrist pin bores weren't touched and they were out 7+ grams.

Be careful with your choices and double check all you can

 

[The Kansan]

Sad part of it is that most machine shops do not balance as close as you would expect. They may mix heavy pistons and light rods and so on. Talk in depth about that and your expectations.

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Ok thanks for the info. The guy thats doing it is really sharp and has done machining/balancing for my dad and myself in the past but im gonna be a lil picky on this build do to the sheer cost of one of these engines. A lil different from a sbc/bbc to a duramax. Is getting within a couple grams of each rod/piston set reasonable? How close do you recommend getting them?

 

[The Kansan]

Engine machining is already done and was done with a torque plate and was align honed with main studs. So that part is already done.

 

[S Phinney]

Ok thanks for the info. The guy thats doing it is really sharp and has done machining/balancing for my dad and myself in the past but im gonna be a lil picky on this build do to the sheer cost of one of these engines. A lil different from a sbc/bbc to a duramax. Is getting within a couple grams of each rod/piston set reasonable? How close do you recommend getting them?

Get with 1 gram total. That would be +/- .5 grams. They probably would want to be off a little more but that is the general high performance spec.

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[57ringo]

I just got my stuff back from the shop Friday and it's within .5 gram

 

[The Kansan]

Good deal thanks for the info...