Here's another question Eagle cast crank 408
#837135
10/23/10 11:37 PM
10/23/10 11:37 PM
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Joined: Jan 2003
Posts: 4,518 Indiana
MonGoo$e
OP
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OP
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Joined: Jan 2003
Posts: 4,518
Indiana
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Some of you know I have a wicked vibration in the Duster at about 55+ and I get it in surges now and then at lower speeds. I've suspected Axles since thats the only thing I didn't touch in the cars going-through. the right rear seems to have a slight wobble to it.
But with the motor..
My set up is an early 360, with the Eagle Cast 4" crank. I have the Professional products balancer. I had a Boss Hogg TC that I am pretty sure of my memory has no added weights on it. I have the B&M flexplate with the offset as well.
I know i need to get with engine builder on how it was balanced exactly, but I noticed Eagle states their cast pieces are external balance.
With that in mind when I was setting at a light tonight, at idle, the car kinda shudders, you hear the steelwork of the body just buzzing. That and the bad vibration makes me curious about the balancer, etc the balancer has the weights you can add, depending on what you have. currently, this balancer has no weights in it. It's set for a neutral balance.
I'm just wondering, until I can talk to machine shop.
Last edited by MonGoo$e; 10/23/10 11:39 PM.
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Re: Here's another question Eagle cast crank 408
[Re: Jeremiah]
#837139
10/24/10 02:09 AM
10/24/10 02:09 AM
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Joined: Jan 2003
Posts: 4,518 Indiana
MonGoo$e
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OP
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car was idling at about 750. and yes when it got below 900 is when it did it. I kicked the idle up a touch at the carb.
I had the driveshaft cut and balanced at a large truck shop, guy that does them ..thats his main job, all the time. I still won't count it out though, has new joints on it.
8 1/4 has all new bearings, inside the tubes and the carrier, pinion, etc.
I have Cragars and BFG's, when we had car up on stands, in drive with no gas applied, the passenger rear wheel down to the center cap you would notice a wobble. looking directly at the rim edge, you noticed it would move up and down about 1/16"-1/8" I stuck a stock steel rim/tire on there and it wasn't as bad, but it was still there. driver side was very minimal.
This is what made me think axles.
oh and at the transmission, I have a new Poly mount.
The vibration, when i hit the upper highway/Interstate speeds, gets a bit violent, I first feel it in my lower back against the bench seat, the lower, and I do mean lower part of the dash frame shakes, and besides that, everything else feels 'heavy' in the rear...it's a cycling, fluxuating pulse vibration...feels like something could come apart 'back there' and it seems to effect the speed too. Almost tried to slow you down. Other than that I tend to get it in stages...down a city street at about 25 it doesn't feel smooth, and sometimes i can accellerate out of it, but usually i can't unless i stop and start over.
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Re: Here's another question Eagle cast crank 408
[Re: MonGoo$e]
#837142
10/24/10 11:06 AM
10/24/10 11:06 AM
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Joined: Jan 2003
Posts: 1,255 Columbus, GA
Michael Ecks
pro stock
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pro stock
Joined: Jan 2003
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Columbus, GA
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Something doesn't sound right with the balance setup. I admit I don't know stroker cranks, but a stock 360 external balance crank needs offset balance weights on both the front and rear at the same time. I can't imagine why a cast stroker advertised as being external balance would be any different in needing it on both ends.
I am assuming that the shop supplied the harmonic balancer? If they shipped the motor with no weights on it, it is possible that they internally balanced the cast crank using mallory metal. in which case you should not be using the offset weight flexplate you have on there now.
If you bought and installed the flexplate and balancer yourself, they need to be balanced to the rotating assembly, since it is extremely unlikely that it would match up with stock 360 offset weights.
"The happiness of your life depends upon the quality of your thoughts" ~ Roman Emperor Marcus Aurelius
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Re: Here's another question Eagle cast crank 408
[Re: HP Engines]
#837151
10/25/10 01:03 AM
10/25/10 01:03 AM
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Joined: Mar 2003
Posts: 9,100 Rogue River, OR
Jeremiah
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Rogue River, OR
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Quote:
Hey buddy, = If its any help , I build alot of strokers at my engine shop. The PP balancers for sbm use the same part#. The difference is they have changeable weights that bolt to back of the balancer. You defenitley have to use the correct weight. It'll tell you in the paperwork wich part# to use. I think its 900something. = The cast Eagle cranks are set up for ext. balance. = I would think you should have a weight on your converter aswell. Ive got several bad reviews on Bosshogs, but havent had 1st hand withem. = 8 1/4s are pretty tuff. I have built and heavily abused several of them. I would check axle runout, and wheels for warpage or proper balance.(none of this concerns shake at idle though) So yeah you may have multiple issues. Maybye the carrier brg. preload has been set way to tight? hope this helps
Out of curiosity, did any of these 8.25's get exposed to a manual trans, extreme traction, or both? I was always pretty amazed at what the 8.25 in my Valiant would handle. Well, until is broke...
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Re: Here's another question Eagle cast crank 408
[Re: HP Engines]
#837153
10/25/10 11:09 AM
10/25/10 11:09 AM
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Joined: Jan 2003
Posts: 1,255 Columbus, GA
Michael Ecks
pro stock
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pro stock
Joined: Jan 2003
Posts: 1,255
Columbus, GA
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Quote:
= I would think you should have a weight on your converter aswell. Ive got several bad reviews on Bosshogs, but havent had 1st hand withem.
The OP said he has the B&M flexplate with the offset (weight I am assuming). If you have the correct weighted flexplate then you can't use the larger external balance weights on the converter or you are doubling the offset weight, putting it back out of balance. One or the other, not both. That said, most converters have small weights added on after rebuild to bring it back to neutral balance on its own, like balancing a tire.
I was not aware that internal/external harmonic balancers had weights that bolted to the back.. I guess I assumed they would bolt to the front cause thats where ma mopar put them. To the OP, when you said there were no weights on it where you just looking at the front like I would have done, or are you sure they are not bolted in from behind?
Oh, and I am not a fan of BossHog converters having had a bad experience, though there is a post you can search for where someone claims their quality has improved since then.
"The happiness of your life depends upon the quality of your thoughts" ~ Roman Emperor Marcus Aurelius
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