middle 2 mains lost

[MoJo]

Re: middle 2 mains lost

This, (50/100%) as I understand, is common. I did not know about the bob weight issue. Is that a journal width issue or?

The V8 and V6 Chevrolet rod journals are different sizes and use different bob weights. .
The Chevrolet 4.3L V6 has 2.250" OD x 1.780" wide.rod journals.
The Chevrolet V8 has 2.000" or 2.100" OD x 1.990" wide rod journals.

My engine builder said that after my crankshaft was internally balanced, he added my new TCI flex plate and Pioneer harmonic damper to the crankshaft in order to see if they were truly neutral balanced. He recommended doing that especially with an aftermarket damper and flex plate. I supplied a Pioneer 872021 damper and a TCI 399774 flex plate that has a counter weight and they were neutrally balanced.

 

[BMFB]

Re: middle 2 mains lost

interesting....I'll have to talk to my builder about these things.

 

[89shortbox]

Re: middle 2 mains lost

The crankshaft is different between 200, 229 , and 4.3(262)

The 200 was a common pin like the v8. This motor was odd fire.
The 229 had a offset rod pin but was semi-even fire.
All PRODUCTION 4.3(262)s are true even-fire with yet a different offset rod pin config.

All these motors need to be balanced differently.

 

[BMFB]

Re: middle 2 mains lost

The crank is cracked apparintly...I'm a bit suprised...I'm on the search for a new one I guess...

 

[TNPhoon]

Re: middle 2 mains lost

Good luck! I think we went through 2 or 3 cranks before Jeff was able to find one for #1377 that didn't have a crack. Can't recall if it was a stocker or if we wound up going scat.

 

[BMFB]

Re: middle 2 mains lost

This was a scat crank

 

[Throws]

Re: middle 2 mains lost

Good luck! I think we went through 2 or 3 cranks before Jeff was able to find one for #1377 that didn't have a crack. Can't recall if it was a stocker or if we wound up going scat.

At this point... I'd go Scat. Nice, new, virgin.

-P

 

[Throws]

Re: middle 2 mains lost

This was a scat crank

:/ Manufacturing flaw or ??

-P

 

[BMFB]

Re: middle 2 mains lost

I suppose its hard to say. I believe it wasn't balanced correctly when it was put together. My builders not acting like this is his fault for some reason...I need to have a talk with him I think...I believe that if he were to have built it and balanced it wrong, and the motor were to come apart for that reason it would be on his hands, but I'm not sure how all that works.

 

[Throws]

Re: middle 2 mains lost

I suppose its hard to say. I believe it wasn't balanced correctly when it was put together. My builders not acting like this is his fault for some reason...I need to have a talk with him I think...I believe that if he were to have built it and balanced it wrong, and the motor were to come apart for that reason it would be on his hands, but I'm not sure how all that works.

I definitely think if assembly was wrong, it's on him. Hopefully he's stand up enough of a guy to admit it and make it right.

-P

 

[BMFB]

Re: middle 2 mains lost

Good news, scat no longer makes a cast crank for the 4.3, although they do make a billet version starting at 3,000 dollars.

My builders supplier still has one sitting on a shelf for 380 bucks, might have to go that route...

 

[neildemo]

Re: middle 2 mains lost

I BelieveI have one on the shelf Brian. Dam actually have 2. Hit me up.

 

[johnboy89]

Re: middle 2 mains lost

Good news, scat no longer makes a cast crank for the 4.3, although they do make a billet version starting at 3,000 dollars.

My builders supplier still has one sitting on a shelf for 380 bucks, might have to go that route...

The Scat website still shows a listing for a 4.3L cast crankshaft??????

 

[Throws]

Re: middle 2 mains lost

The Scat website still shows a listing for a 4.3L cast crankshaft??????

I'm not really sure Scat is up on their website... actually a lot of people consider them pretty static things. Post once and then forget.

-P

 

[BMFB]

Re: middle 2 mains lost

I called them and its what they said, but it does still show them up on the website. My builder thought 3k for a billet crank was outrageous.

Anyway I talked to him, and he says he will do all of the machining for free, and some of the assembly. He can get the crank for about 300, and I have to pay that as well as gaskets and bearings and thats it.

After talking to him today I am not sure if I misunderstood him before or what, but he believed that it was balanced externally and it just cause alot of flex in the crank. He thinks that internally balancing it will get rid of those issues and make the whole thing alot less prone to flexing. I believe if he gets the crank from scat and its internally balanced its going to be another story...which is how I think its going to play out...either way I am hoping to have the motor back in 2 weeks so I can get it together. I am not missing homecoming goddamnit.