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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$e
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OP
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Indiana
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Some of you know I have a wicked vibration in the Duster at about 55+ and I get it in surges now and then at lower speeds. I've suspected Axles since thats the only thing I didn't touch in the cars going-through. the right rear seems to have a slight wobble to it.
But with the motor..
My set up is an early 360, with the Eagle Cast 4" crank. I have the Professional products balancer. I had a Boss Hogg TC that I am pretty sure of my memory has no added weights on it. I have the B&M flexplate with the offset as well.
I know i need to get with engine builder on how it was balanced exactly, but I noticed Eagle states their cast pieces are external balance.
With that in mind when I was setting at a light tonight, at idle, the car kinda shudders, you hear the steelwork of the body just buzzing. That and the bad vibration makes me curious about the balancer, etc the balancer has the weights you can add, depending on what you have. currently, this balancer has no weights in it. It's set for a neutral balance.
I'm just wondering, until I can talk to machine shop.
Last edited by MonGoo$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
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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: 9,098
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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Re: Here's another question Eagle cast crank 408
[Re: chache876]
#837155
10/25/10 07:42 PM
10/25/10 07:42 PM
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Joined: Jan 2003
Posts: 4,518
Indiana
MonGoo$e
OP
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OP
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I spoke with Engine builder today, well known Mopar guy, he told me currently, he has to farm his balancing out, so he remembered it well, when it was being done, the guy working on it said "you need this weight on it" Abotu a week later he went back and the owner had the balancer, etc on, and without the weight, Engine guy asked "what about the weight?" Owner of the balance shop said "it'd good where it's at"
He said with that he figured they neutral balanced it or something..He was a little frustrated with the guy because the guy isn't saying much, anyways thats one story for another day but he suggested trying the 3 weights, first starting with smallest (I have weights and paperwork) the largest is the original 71+ style 360 weight. I'd like to just do that one but I have no idea what the eagle 4" cranks are based off of.
I'm a little annoyed with this but I'm sure I'll figure it out sooner than later with this trial and error stuff.
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Re: Here's another question Eagle cast crank 408
[Re: MonGoo$e]
#837156
10/25/10 09:12 PM
10/25/10 09:12 PM
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Joined: Jan 2003
Posts: 9,826
las vegas
70AARcuda
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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Quote:
I spoke with Engine builder today, well known Mopar guy, he told me currently, he has to farm his balancing out, so he remembered it well, when it was being done, the guy working on it said "you need this weight on it" Abotu a week later he went back and the owner had the balancer, etc on, and without the weight, Engine guy asked "what about the weight?" Owner of the balance shop said "it'd good where it's at"
He said with that he figured they neutral balanced it or something..He was a little frustrated with the guy because the guy isn't saying much, anyways thats one story for another day but he suggested trying the 3 weights, first starting with smallest (I have weights and paperwork) the largest is the original 71+ style 360 weight. I'd like to just do that one but I have no idea what the eagle 4" cranks are based off of.
I'm a little annoyed with this but I'm sure I'll figure it out sooner than later with this trial and error stuff.
if they internally balanced it you will slugs of mallery metal in the front and rear counterweights on the crank...
yes...let's try 3 different weights on the balancer..LOL...sorry
Tony
70 AARCuda Vitamin C
71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield)
71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas)
71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: Here's another question Eagle cast crank 408
[Re: 70AARcuda]
#837157
10/25/10 10:17 PM
10/25/10 10:17 PM
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Joined: Sep 2004
Posts: 2,091
oberlin, Ohio
Rapid340
top fuel
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top fuel
Joined: Sep 2004
Posts: 2,091
oberlin, Ohio
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I have seen one guy balance for an offset weighted damper but a neutral flexplate.
BTW, you really got a raw deal from the sound of it.
1971 Factory Appearing Duster 340 11.000 @ 122 mph
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Re: Here's another question Eagle cast crank 408
[Re: Rapid340]
#837158
10/25/10 10:33 PM
10/25/10 10:33 PM
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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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... Um... Okay it sounds like you have indeed gotten a bad deal on this thing. If the engine builder actually said to just go ahead and try the different weights then he is a f____ng moron and you need to find a new engine builder, I don't care how well known of a mopar guy he is. Your best starting place in my opinion if he claims the balance guy said it was good where it was, would be to remove the offset balance flexplate and bolt on a neutral one along with the neutral balance converter. 
"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: Michael Ecks]
#837160
10/26/10 12:52 AM
10/26/10 12:52 AM
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Joined: Jan 2003
Posts: 4,518
Indiana
MonGoo$e
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OP
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Quote:
Quote:
= I would think you should have a weight on your
converter aswell. Ive got several bad reviews on Bosshogs, but havent had 1st hand withem.
The OP said he has the B&M flexplate with the offset (weight I am assuming).
it's the ones thats round but has the sliver cut from one side of the plate. it looks like this one:
http://carphotos.cardomain.com/ride_images/1/3035/461/7585230071_large.jpg
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Re: Here's another question Eagle cast crank 408
[Re: MonGoo$e]
#837162
10/26/10 07:25 PM
10/26/10 07:25 PM
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Joined: Jan 2003
Posts: 9,982
Ansonia, CT
CJK440
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master
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Ansonia, CT
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It will contradict what some people say, but all I can do is share my experiences.
I built a 408 using an eagle 4" cast crank, eagle H beams and SRP forged slugs. It was supplied as an internally balanced rotating assembly. When I received it I noticed it only needed minor drilling to internally balance, no mallory at all. It seemed odd to me and I contacted the shop and there is apparently some misinformation with eagle's specs on their cranks.
I put a neutral balance SFI damper on front and a neutral flexplate/converter combo and it ran great. Ran 11.90s in my F.A.S.T. Duster while the big motor was being built.
2017 Contusion Blue Challenger T/A 392 M6 "BLKNBLU"
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Re: Here's another question Eagle cast crank 408
[Re: mod381]
#837165
10/26/10 08:52 PM
10/26/10 08:52 PM
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Joined: Sep 2004
Posts: 2,091
oberlin, Ohio
Rapid340
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top fuel
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oberlin, Ohio
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If I remember correctly Eagle cast 4 in cranks have a target bobweight of 1850 grams. They have been made that way for a couple years so it could be neutral balanced. If your rods/pistons/rings/bearings didnt work out to more than 1850, neutral balancing would have taken the least effort and cost to balance. If it were me that is what I would try next. Swap the half moon flexplate for a std one and damper also if the current one is not a neutral damper.
1971 Factory Appearing Duster 340 11.000 @ 122 mph
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Re: Here's another question Eagle cast crank 408
[Re: Rapid340]
#837166
10/26/10 09:37 PM
10/26/10 09:37 PM
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Joined: Feb 2003
Posts: 12,675
Columbia, CT
moper
I Live Here
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I Live Here
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I internally balance all my engines. With two seperate builds and Eagle cast cranks:
1 - stock rods, forged pistons - needed Mallory.
1 - SIR Eagle rods, forged pistons, needed only drilling (and a lot of it).
If you have a vibration, it is well worth taking it apart and having a shop properly address it. You might get it better but not right, and that crank is not known for taking a lot of abuse well.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: Here's another question Eagle cast crank 408
[Re: moper]
#837167
10/26/10 10:14 PM
10/26/10 10:14 PM
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Joined: Jan 2003
Posts: 9,982
Ansonia, CT
CJK440
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master
Joined: Jan 2003
Posts: 9,982
Ansonia, CT
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Quote:
I internally balance all my engines. With two seperate builds and Eagle cast cranks:
1 - stock rods, forged pistons - needed Mallory.
1 - SIR Eagle rods, forged pistons, needed only drilling (and a lot of it).
If you have a vibration, it is well worth taking it apart and having a shop properly address it. You might get it better but not right, and that crank is not known for taking a lot of abuse well.
Mongoose, I know you don't want to hear it but Moper is on target. Only way to be sure.
I would stop mismatching offset balanced stuff. If you have a vibration with the external balance 360 crap then to me the only crapshoot before pulling it all apart would be going with neutral balance stuff and giving it a go. Since you have a pick-your-imbalance balancer and stock mopar flex plates are a dime a dozen, the only thing it will cost you is labor.
Perhaps a little more info would help. What rods and pistons are in that motor?? I'm assuming there is no balance sheet available from the balance shop with all the weights recorded?
2017 Contusion Blue Challenger T/A 392 M6 "BLKNBLU"
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Re: Here's another question Eagle cast crank 408
[Re: CJK440]
#837168
10/26/10 10:52 PM
10/26/10 10:52 PM
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Joined: Jan 2003
Posts: 4,518
Indiana
MonGoo$e
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OP
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I'm a bit annoyed tonight, I placed a call to the engine builder, it actually surprises me greatly he wasnt sure from the get-go about my crank. he explained the bob weight, and that the shop he takes them to usually externally balances, (based on early post you'll notice the story) Well he said they must have screwed up somewhere and forgot to add that weight on, he suggested the middle weight, well I stuck it on, and in 20 minutes I had it back on, i started it and right away it was shaking, I shut it down and ruled that particular weight out. He said the offset plate I'm using is fine, they are using that on the strokers. If anything I'm confused, guy used to work on this stuff professionally in the 60's-70's in Florida and I feel like I'm an exception here. I asked him to get in touch with that shop and get me some info, he said they don't keep records.  I'm just going to do with what I can at this time, All I've done is work with this thing since I put it together. I went ahead and popped the balancer off again tonight and I'm going to try that small one, just to see what it does on start up. Moe and more I'm wishing I would have just stuck with a 360 crank, that way you just slip a stock balancer on there and forget about it. I'm not interested in worrying about this stuff. But I'm forced to. If anything, he can fix the motor at his expense if need be. bad deal.
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Re: Here's another question Eagle cast crank 408
[Re: MonGoo$e]
#837169
10/28/10 05:02 AM
10/28/10 05:02 AM
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Joined: Jan 2003
Posts: 3,943
Melbourne.....Oz-land
Moparmal
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master
Joined: Jan 2003
Posts: 3,943
Melbourne.....Oz-land
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Quote:
I built a 408 using an eagle 4" cast crank, eagle H beams and SRP forged slugs. It was supplied as an internally balanced rotating assembly. When I received it I noticed it only needed minor drilling to internally balance, no mallory at all. It seemed odd to me and I contacted the shop and there is apparently some misinformation with eagle's specs on their cranks.
I put a neutral balance SFI damper on front and a neutral flexplate/converter combo and it ran great. Ran 11.90s in my F.A.S.T. Duster while the big motor was being built.
X1 and ditto - Check half way down -
Eagle crankshafts
Choose "Chrysler" and then "360" - it lists options for the 360 cast crank (external) and the 4" (Internal)
The Eagle site clearly states that the 4" cast Eagle is set up for INTERNAL balancing.
If you try to externally balance it, you need to rip more metal from the crank than necessary.
Some suppliers get it wrong - but your builder should have checked.
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Re: Here's another question Eagle cast crank 408
[Re: MonGoo$e]
#837171
10/28/10 01:36 PM
10/28/10 01:36 PM
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Joined: Jan 2003
Posts: 8,089
Sorrento, BC, Canada
4speeds4me
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Sorrento, BC, Canada
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Mongoo$e- If the crank was, in fact, internally balanced, and you are using the B&M "weighted" flexplate (the one with the part moon cutout) then you have added an external balance flexplate to an internal balance engine.
I am somewhat appalled at the lack of paper trail your engine has. When I built my 408 the balancer gave me a detailed readout. Bobweight, breakdown of each piece, how much mallory metal and the final readout of the recip assembly, etc. That way, if I ever needed to replace one component due to failure, I wouldn't need to start from scratch.
2 Demons...no, not my kids! 
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Re: Here's another question Eagle cast crank 408
[Re: MonGoo$e]
#837173
10/28/10 08:30 PM
10/28/10 08:30 PM
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Joined: Feb 2003
Posts: 12,675
Columbia, CT
moper
I Live Here
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I Live Here
Joined: Feb 2003
Posts: 12,675
Columbia, CT
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As I said, that crank is not a stout piece. If it's out, and to me it sounds like your shop guys purely guessing (and guessing wrong), that crank won't last with much abuse. It's cheaper to pull it out and fix it, than replace it when the crank breaks.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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Re: Here's another question Eagle cast crank 408
[Re: moper]
#837175
10/28/10 09:13 PM
10/28/10 09:13 PM
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Joined: Jun 2004
Posts: 893
Tustin, CA
pishta
super stock
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super stock
Joined: Jun 2004
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Tustin, CA
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Every place that sells Eagle cast ("the 360400" like part number)says in the ad is external balance, but any crank can be internally balanced. The forged are more dense so that usually equates to an internal balance as the crank counterweights are as heavy or heavier than the reciprocating weight, the cast are lighter so you need to add weight with weights on the flex/flywheel and/or balancer. This is ASSUMING that you are using stock weight pistons and rods. Most stroker pistons are shorter, hence lighter than stock pieces (which are heavy from the factory) so the "adding weight to balance" is misleading if you are using non factory weight parts. Heavy forged pistons require heavy metal to be added to the counterbalance to counterbalance the crank. If you go lighter, and who doesnt these days, you end up taking metal away (drilling) from the counterbalance. I got an Eagle cast 360400 crank and am using stock 360 rods and MP cast stroker pistons for a mild build (and cheap I may add) I did the calculations and weights with a digital .01g resolution scale with a shop buddy and took about 8g off each rod and equalized everything (pistons, rods, pins)to .5g and the cast crank balanced on the machine to within +15g or so and the guy says youll probably pick that up in oil anyway. He was very suprised how close we got it and that was just going off the published bobweight of the crank. He also told me that press fit pins can be shortened if you couldnt take any more meat off the pistons or rod little end (trying to lighten aluminum pistons grams at a time, you run out of meat pretty fast) as the pins are rather heavy items and even 1-2mm of an end is measurable weight when you are looking at g's.
I remember seeing a SCAT lightened crank that was using LY rods and forged 440 pistons, that crank had about $500 in mallory slugs in its counterbalances to make it work with the heavy reciprocating weight. IIRC, Mopar "detroit" balanced the 360 with the balancer and convertor/flywheel attached, so you cant get away with one or the other has to be both if getting a 360 crank. all other LA's(not cast 73 340) were neuteral balanced, as they all should have been, and that is because the cast 360 was using the 340 rods (heavy)without the hole drilled in the (lightened) rod journal, ala forged 340. Its a black art indeed.
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Re: Here's another question Eagle cast crank 408
[Re: MonGoo$e]
#837178
10/29/10 07:40 AM
10/29/10 07:40 AM
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Joined: Jan 2003
Posts: 3,943
Melbourne.....Oz-land
Moparmal
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Melbourne.....Oz-land
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This is from the Eagle webs site under Chryser 4" cast crank specs: - 4.0000 103604000 cast internal bal. bob weight 2050
HP rating 500 Perhaps the reason that some shops say its for "external" balance is the same reason you are having issues now....they are clearly confusing the 360 factory replacement crank (which Eagle says IS made for an external balance).......with the cast stroker item. FWIW - the Cast = external vs forged = internal theory doesn't work - Myself and several others I know run the Cast 340 4" crank and ALL have been internally balanced with very little metal needing removal..and NONE needing additional metal. (This is using KB slugs and eagle rods.) I agree with CJK - Strip the flex plate and damper and use a neutral assembly - hopefully they haven't butchered your crank completely....if they did anything at all? 
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Re: Here's another question Eagle cast crank 408
[Re: Moparmal]
#837179
10/29/10 10:37 AM
10/29/10 10:37 AM
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Joined: Jul 2007
Posts: 1,682
Philadelphia
radar
top fuel
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top fuel
Joined: Jul 2007
Posts: 1,682
Philadelphia
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Like I said, my 408 with eagle cast 360 style crank was internally balanced. I have sir rods and kb forged pistons. I use a neutral flywheel and balancer. Why would I lie about it?I had it balanced but I put everything together myself.  Don't pull your hair out. Just pull the transmission and change out the flex plate. If you wanted your hands to stay clean you would drive a new Honda civic, right? That's why we do this stuff, isn't it? It will make the ride that much sweeter after you go through all this crap. My stroker is tons of work but so much fun. It's totally worth the trouble. Good luck rdr
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Re: Here's another question Eagle cast crank 408
[Re: radar]
#837180
06/27/14 01:46 AM
06/27/14 01:46 AM
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Joined: Jun 2004
Posts: 893
Tustin, CA
pishta
super stock
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super stock
Joined: Jun 2004
Posts: 893
Tustin, CA
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bringing this back from the dead...Why do you suppose they use 1 piston /pin but use 2 rods weights when figuring the bobweight? And do they measure the big and little ends using the other ends centerline as the pivot?
12 Grand Caravan
06 T&C
02 T&C
96 Breeze
65 Barracuda "S"
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As far as your vibration is concerned I'd be looking at replacing the rear with a 8.75 and if you have yet to install a heavier drive shaft/u-joints I'd be willing to bet the shaft is bent.
Good luck with it. 
