Eagle cast steel cranks

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Dont forget sometimes the cost difference between cast and forged narrows when you start ballancing and need to add heavy metal to that cast crank.
 
A 318 works very well with a 4 inch crank. Add in Edelbrock heads with a four angle valve job, Comp XE274H, an air gap, and a 750 4150 and it will keep pulling up to around 6800 rpm and still have plenty of bottom end torque. I’m sure the 11.3 1 or so compression helped out with that too, though! Just a great hot rod street engine. Unless your heads have a W prefix and are worked pretty seriously, I do agree with 3.79 inch crank for the larger bore sizes.
 
Garrett Ellison said:
A 318 works very well with a 4 inch crank. Add in Edelbrock heads with a four angle valve job, Comp XE274H, an air gap, and a 750 4150 and it will keep pulling up to around 6800 rpm and still have plenty of bottom end torque. I’m sure the 11.3 1 or so compression helped out with that too, though! Just a great hot rod street engine. Unless your heads have a W prefix and are worked pretty seriously, I do agree with 3.79 inch crank for the larger bore sizes.
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A 270S I would like better.
 
RustyRatRod said:
A 270S I would like better.
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The Eagle forged crank in my R3 /408 after 200 or so runs shifting at 6500

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Rat Bastid said:
I‘ve seen that before and it’s not a crank failure. That’s a damper issue/failure.
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Don't think so .. new ATI Super Damper and it was fine on the dyno . I am just lucky all it did was take out the main bearing and not damage the precious R block. .. and replacement cost for a better crank is $900 to $1100... it happened last year and I am running my backup 367 now , probably going to fix it over the winter
 
BVoelzke said:
Don't think so .. new ATI Super Damper and it was fine on the dyno . I am just lucky all it did was take out the main bearing and not damage the precious R block. .. and replacement cost for a better crank is $900 to $1100... it happened last year and I am running my backup 367 now , probably going to fix it over the winter
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I’d have someone look at it that understands harmonics because that’s a fracture that occurs when you have a frequency issue.

I had a war with ATI in 1989. Their dampers are tuned for a very narrow range. When you call them and tell them you have a certain bob weight and an RPM range that most don’t run, and they try and sell you a damper that is tuned for lower RPM, heavier bob weight…I have an issue with that.

Like I said, I’ve seen several cranks broken like that and a couple of them were in the first stages of failure. All of them were damper related.
 
Rat Bastid said:
I’d have someone look at it that understands harmonics because that’s a fracture that occurs when you have a frequency issue.

I had a war with ATI in 1989. Their dampers are tuned for a very narrow range. When you call them and tell them you have a certain bob weight and an RPM range that most don’t run, and they try and sell you a damper that is tuned for lower RPM, heavier bob weight…I have an issue with that.

Like I said, I’ve seen several cranks broken like that and a couple of them were in the first stages of failure. All of them were damper related.
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Thanks for the info , I will look into it as I never thought of the balancer going bad but it could very well be as a matter of fact this motor had a previous problem ( wiped the bearings while on the dyno after the initial build ) I wonder if the problems are related ?
 
BVoelzke said:
Thanks for the info , I will look into it as I never thought of the balancer going bad but it could very well be as a matter of fact this motor had a previous problem ( wiped the bearings while on the dyno after the initial build ) I wonder if the problems are related ?
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Very well could be. Those types of damper have one HUGE benefit. They can be rebuilt. And they should be. The damping materiel (O rings) lose durometer as they go through heat cycles/use.

When that happens the tune on the damper changes and that can cause a crank failure and other weird things that one might no suspect being a damper issue.
 
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