Rebalancing 4340 external crank

tconnection May 20th 2011, 12:01 am

I got a heavier piston than what my crank was balanced with. They are like 32grams heavier. Would my crank have to have weight added or subtracted?
Thanks for any info.

rmcomprandy May 20th 2011, 12:20 am

tconnection wrote:I got a heavier piston than what my crank was balanced with. They are like 32grams heavier. Would my crank have to have weight added or subtracted?
Thanks for any info.

ADDED ... however, if you can use a lighter tool steel pin, you may get closer to where you need to be.

tconnection May 20th 2011, 10:43 pm

The pins are the H-13 tool steel. The rings are .043,.043,3/16 with a rail support.
I was mainly wondering about the cost of rebalancing with mallory.
Thanks alot!

c.evans May 20th 2011, 11:14 pm

The cost of rebalancing with mallory is very expensive. Why did the pistons come in 32 grams heavier, than what you had the crank pre-balanced too?

What Randy said is correct,,,,is there any chance you can go with a thinner wall H-13 tool steel pin?

Charlie

tconnection May 21st 2011, 12:00 am

the pistons that i was gonna use are 4.440 and weigh 608gr and the ones that i got ordered are 4.530 and i think they weigh about 628 or 630gr. Im gonna call diamond to check on a thin wall pin.
Thanks for all and anymore info.

Lem Evans May 21st 2011, 9:21 am

Send them back to Diamond and have them perform the MAXI-LITE milling option.

tconnection May 21st 2011, 10:54 am

I just orded them thur 2 days ago. They'll probably start building them monday but i think its like an extra $100 bucks to lighten them which is fine i guess but would that weaken the piston in any way?
Thanks alot men.

Lem Evans May 21st 2011, 11:28 am

It's about $9 per piston.

rmcomprandy May 21st 2011, 11:39 am

Of course it will weaken them somewhat ... a 1/2" thick piece of metal is stronger than a 3/8" piece of metal however, when the strength of a 1/4" piece of metal will suffice then the ultimate amount of weakening is moot.

The MAXI-LITE treatment is a bunch less expensive than re-balancing with Mallory.

Lem Evans May 21st 2011, 9:27 pm

I see you bought these pistons direct from Diamond........so did they not offer you this option?

tconnection May 21st 2011, 11:56 pm

I for sure dont want to weaken them. If rebalancing is gonna be over $300 I may just sale this crank and get another. The guy that's buying my other pistons may buy it. After this change i aint changing nothing else. Its just that there's a few heads uma chop off at da shoulders and wanna do it with ease.
Thanks alot again and again.

tconnection May 22nd 2011, 12:15 am

The fellow told me about the option. Im gonna call monday to see if it weakens much. If the option is moot then, why not get it done. Hell i think!
How does this work? I mean, is it that the closer i can get to 608gr, the less rebalancing would cost?

Mark O'Neal May 23rd 2011, 12:57 pm

Just tell Diamond what you pistons weigh and that you need then at that number.

tconnection June 21st 2011, 11:25 pm

Can this balanced external crank be converted to an internal balance? And about what would have to be done to the crank if so?
Thanks

DanH June 22nd 2011, 10:25 am

tconnection wrote:Can this balanced external crank be converted to an internal balance? And about what would have to be done to the crank if so?
Thanks

add heavy metal and fill in drilled holes in the counter weights

tconnection June 22nd 2011, 1:03 pm

About what's the rpm limits for an eagle external 4340 crank?
Thanks

tconnection July 8th 2011, 1:06 am

Im looking in to getting some thin wall pins that would weigh less than what i had and have.
The pistons i had weighed 608g and the pin weighed 174.2g, That's 782g.
The pistons i have now weighs 636g. That's a 28g differance. Do the present weight need to be 782g to stay close to the balanced crank bob weight? I don't know the ring weight which was 1/16 1/16 3/16 but now is .043 .043 3/16 which may be a little lighter.
With the 636g piston and a 144g pin adds up to 780g. Does all this sound bout right in order to not have to rebalance my crank?
Thanks

Maddmattmustangs July 8th 2011, 1:53 am

Id listen to rmcomprandy and lem they build some real strong motors and if they say lightening the piston won't kill the motor then it wont. if anything a lighter piston will probably make the package stronger as a whole. I wish i would have started listening to them a lot sooner than i did trust me.

rmcomprandy July 8th 2011, 10:41 am

tconnection wrote:Can this balanced external crank be converted to an internal balance? And about what would have to be done to the crank if so?
Thanks

Of course it CAN ... with each piece of heavy mallory metal installed will cost you about 50 bucks, plus the cost of a regular balance job.
If the crank is external now, then it will probably need 4 or 5 slugs.
Balancing internal in the FRONT and keeping the rear external will probably need 2 or 3 slugs

tconnection July 8th 2011, 9:23 pm

tconnection wrote:Im looking in to getting some thin wall pins that would weigh less than what i had and have.
The pistons i had weighed 608g and the pin weighed 174.2g, That's 782g.
The pistons i have now weighs 636g. That's a 28g differance. Do the present weight need to be 782g to stay close to the balanced crank bob weight? I don't know the ring weight which was 1/16 1/16 3/16 but now is .043 .043 3/16 which may be a little lighter.
With the 636g piston and a 144g pin adds up to 780g. Does all this sound bout right in order to not have to rebalance my crank?
Thanks

tconnection July 8th 2011, 9:38 pm

I haven't talked with the machine shop about this other than that he would have to add some weight.
Im just trying to understand about using a lighter pin to get the balance right with my crank.
thanks

tconnection July 8th 2011, 9:42 pm

what if i stay external and go with a lighter 144g pin?

rmcomprandy July 8th 2011, 10:09 pm

tconnection wrote:what if i stay external and go with a lighter 144g pin?

The final balance doesn't care whether the extra weight is removed from the piston, pin or small end of the rod as long as the reciprocating total weight is correct.

tconnection July 8th 2011, 11:46 pm

Ok, with the crank already balanced with the former 608g pistons and 174.2g pins,
and now spinning the assembly with present 636g pistons and 144g pins, is it most likely that no or very little weight will need to be added? Im about to understand.
Thanks

tconnection July 8th 2011, 11:56 pm

rmcomprandy, thank u and the rest of the men for all info. Im gonna call the machine shop monday to see which thin wall pin i should get.
Thanks again.

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Rebalancing 4340 external crank

Rebalancing 4340 external crank

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Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

Re: Rebalancing 4340 external crank

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