Crank breakers wanted

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I broke the eagle cast crank in my 410. I took it to the dyno (chassis dyno) it only made 355 rwhp. When I drove it home I thought the engine was a bit rattly. The next day I pulled up at a stop light with my window down and thought gee that car next to me must be a diesel because it rattles. But when I reved mine up to take off I relized it was mine rattling. Took it home and pulled the sump off and checked the bearings but all looked fine so put oil back in and started it up but would rattle when you reved it up. I noticed the balancer was wobbling a bit. I put a screw driver behind the balancer a pulled the balancer about qtr inch forward. Ha broken crank! pulled the motor down and after taking the front off the motor the front of the crank just fell out. I bought a steel stroker crank and rebuilt that engine with forged pistons and scat rods and have never looked back. The engine now puts out 425 rwhp ( nearly 550 at the flywheel) No other damage to the motor other than the crank and it drove fine just rattled a bit when you reved it.
 
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Well that was unsuccessful.. managed to drop a valve instead on Number 3 cylinder. This is in my 74 powerwagon 360 and NP435. There was pieces of valve that dropped outa the header when I removed it. I’ll have the front clip off later and I’ll pull the head.
 
:rofl::rofl:Damn! You weren’t Joking! :thankyou: Your Power Wagon’s sacrifice will always be remembered!
 
Garrett Ellison said:
:rofl::rofl:Damn! You weren’t Joking! :thankyou: Your Power Wagon’s sacrifice will always be remembered!
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Hell no I wasn’t. I got that other 360 I’m Halfway building, going back in. I thought I’d see what’ll happen if I give it what it’s good for, one last time! I have a factory tach in the truck, goes to 5K, well I’m sure I was passed that. Those NP435’s sure don’t like to be speed shifted either.
 
mopardude318 said:
View attachment 1715681252 View attachment 1715681253 Well that was unsuccessful.. managed to drop a valve instead on Number 3 cylinder. This is in my 74 powerwagon 360 and NP435. There was pieces of valve that dropped outa the head
mopardude318 said:
Hell no I wasn’t. I got that other 360 I’m Halfway building, going back in. I thought I’d see what’ll happen if I give it what it’s good for, one last time! I have a factory tach in the truck, goes to 5K, well I’m sure I was passed that. Those NP435’s sure don’t like to be speed shifted either.
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Nice block
Be waiting to see it for sale !!!
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I believe you’ve got one of the good early blocks there, like my early crank is out of. That one may have 974 heads, too, but the ‘73 I got the rotating assembly out of had 576 heads on it.
 
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Driving my 67 Barracuda 273 on the Interstate going 75 MPH, didn’t know I had a cracked sleeve, got water in the oil, burned up the mains, started shaking, then locked up tight. Even broke the #3 main mounting boss right off the block.

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Garrett Ellison said:
I believe you’ve got one of the good early blocks there, like my early crank is out of. That one may have 974 heads, too, but the ‘73 I got the rotating assembly out of had 576 heads on it.
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Got the front clip off and a head pulled today. It is a ‘74 block with 974 heads. What makes those heads good?

The piston sure wasn’t havin a good time. The bore looked and feels untouched.
 
Oldmanmopar said:
Never pays to use old bolts on the rods . Many learned the hard way including myself
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Rod bolts are supposed to have 3 torques before you toss them. First is factory torque, second is taking it apart to balance it and third is the only one you do before you should replace them. I read that somewhere...maybe a urban legend. I broke a rod bolt in a 318 as well or it was never torqued...can't remember. Broke a rod in a 351C too. Windowed the block on that one and I wasnt even running it that hard. I think the trans locked up.
 
mopardude318 said:
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Got the front clip off and a head pulled today. It is a ‘74 block with 974 heads. What makes those heads good?

The piston sure wasn’t havin a good time. The bore looked and feels untouched.
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They're a mid to late J type smogger head but with a good exhaust port and (IIRC) a lower volume intake port with a raised floor. A good on a budget iron head and even decent for a 318 build. I came across post by @MOPAROFFICIAL a couple of days back that I cannot locate now where he touches on the J and some of the decent later smogger castings and covers some of the different quirks. I'm hoping to find it again because it explains more than I can remember at the moment.
 
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Garrett Ellison said:
They're a mid to late J type smogger head but with a good exhaust port and (IIRC) a lower volume intake port with a raised floor. A good on a budget iron head and even decent for a 318 build. I came across post by @MOPAROFFICIAL a couple of days back that I cannot locate now where he touches on the J and some of the decent later smogger castings and covers some of the different quirks, I'm hoping to find it again because it explains more than I can remember at the moment.
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Mopar Small Block Head info:

Post #22 and from there.
Could be a sticky.
 
sireland67 said:
Why pull a front clip, just to remove the head?
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I’m doing multiple things. Swapping over to a Dana 60 up front, and crossover steering. So I have to weld stiffening brackets on the frame, so front clip must come off. :) swapping out engine and transfer another 360 I’m building. :)

I will start a build thread on my W200 of there is interest.
 
Back in 1990 i got a 340 that my dad rebuilt in the late 80s ,put it in my 71 duster and drove it for awhile and one day i took off from a stop light car shifted into 2nd and broke the crank behind #2 rod ,car still ran just had a knock, pulled 340 out and 10 years later put new bearings and crank in it and its in my 69 dart haven't had any problems yet.
then i got a 70 duster for my daughter, had a 70 340 out of a different car put it in her car after restoring her duster drove it 2 miles to get appraised went to start it and BANG, crank broke in same spot ,,behind #2 rod, i don't know why they break there but i've had 2 steel cranks do that. ended up getting another crank for her 340 and been good since
 
70duste said:
Back in 1990 i got a 340 that my dad rebuilt in the late 80s ,put it in my 71 duster and drove it for awhile and one day i took off from a stop light car shifted into 2nd and broke the crank behind #2 rod ,car still ran just had a knock, pulled 340 out and 10 years later put new bearings and crank in it and its in my 69 dart haven't had any problems yet.
then i got a 70 duster for my daughter, had a 70 340 out of a different car put it in her car after restoring her duster drove it 2 miles to get appraised went to start it and BANG, crank broke in same spot ,,behind #2 rod, i don't know why they break there but i've had 2 steel cranks do that. ended up getting another crank for her 340 and been good since
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Interesting. I've seen a bunch of 340's, cast and steel cranks ran very hard and have never seen one break.
 
i broke 2 late 1970's 360 cranks , of course back then i had a heavy foot drove the truck for 3 4 hours at a time at over 100mph brought the truck back to the dealer and they just put in a replacement engine no way to rebuild the old one . after the second engine they told me you're on your own this is the last time we are replacing an engine , at least i was able to drive them to the dealer they made lots of noise but made it there . good old days when they didn't have computers monitoring your driving habits .
 
James Clews said:
I broke the eagle cast crank in my 410. I took it to the dyno (chassis dyno) it only made 355 rwhp. When I drove it home I thought the engine was a bit rattly. The next day I pulled up at a stop light with my window down and thought gee that car next to me must be a diesel because it rattles. But when I reved mine up to take off I relized it was mine rattling. Took it home and pulled the sump off and checked the bearings but all looked fine so put oil back in and started it up but would rattle when you reved it up. I noticed the balancer was wobbling a bit. I put a screw driver behind the balancer a pulled the balancer about qtr inch forward. Ha broken crank! pulled the motor down and after taking the front off the motor the front of the crank just fell out. I bought a steel stroker crank and rebuilt that engine with forged pistons and scat rods and have never looked back. The engine now puts out 425 rwhp ( nearly 550 at the flywheel) No other damage to the motor other than the crank and it drove fine just rattled a bit when you reved it.
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If you offered me a brand new Eagle cast crank for free, and 50.00 for gas money to come get it I would still pass on that crank. To many bad stories.
 
pittsburghracer said:
If you offered me a brand new Eagle cast crank for free, and 50.00 for gas money to come get it I would still pass on that crank. To many bad stories.
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i know of 3 eagle cranks that went bad , don't know if it was because lead foot , no maintenance or just bad cranks . For the few 100.00 differences in price i'll spend extra to get a better crank . not worth saving a few 100 on a 10,000 or more build
 
Garrett Ellison said:
Thank you! I halfway thought about it but I'll put the little extra insurance into it. I'm cheaping out badly enough on this 360 build as it is with a set of 14,000 mile '73 HD truck pistons that run .008 deck clearance with a 9.6 inch deck. But I believe I'll probably upgrade there, too, by the time it's over. The snowball priniciple.
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rod bolts are no place to skimp I also learned that the hard way and broke a rod bolt in a 72 340. I never broke a Mopar crank but the majority of my flogging has been on factory forged 340 cranks that I know have seen close to 8,000 RPM on a miss shift you know the type when your teeth clench and your shoulders rise and you say damn it's still together
 
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I bought a very nice machined 340 block, (416) diamond pistons, Scat rods and cast Scat crank, cam and lifters, and a few other things from a friend. This same build had an Eagle cast crank and after hearing stories he upgraded to the above stuff and had it all rebalanced. Like I said the price was right so I bought it. The more I thought about it I was kinda scared knowing it would be a low 10 second high 9 second build so I advertised it and sold it off. I know a stock 360 cast crank is strong but didn’t want to be testing the strength of the Scat stuff even with reports of it being better.
 
Yes Pittsburg! I was collecting parts to build a stroker many years ago and my brother was supplying me the parts over a series of years as I had a growing family and would only buy parts as I had some spare cash. I did not even have the car to put it in. Well my brother likes to build things like a tight arse and said you only need a cast crank as they are good for about 450 HP. He sold me an eagle crank. Speedmaster chev pistons and rods etc. Well when I pulled it down I could see that the valves had been kissing the pistons, the valve reliefs are in the wrong spot for a mopar even though he knows everything , so I spat the dummy and put forged srp pistons in and scat rods and built it myself and have even put trick flow heads on it and it makes 425 RWHP now ( about 550 at the crank!)He originally told me it would only do mid 13s in the qtr but it has already run a 11.5 qtr and am looking forward to going to the track now and see if it runs low elevens and if it does an eleven flat I will never go back to the track again as it is a joy to drive now and behaves perfect in stop start traffic!
 
Not exactly Mopar related, but I get a kick out of these Nordberg engines, and the comment that inspecting the crank was nearly as costly as replacing it....so they adopted a policy to run the engines until the cranks broke!

Nordberg Radial Stationary Engine
 
mopardude318 said:
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Got the front clip off and a head pulled today. It is a ‘74 block with 974 heads. What makes those heads good?

The piston sure wasn’t havin a good time. The bore looked and feels untouched.
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If you elect not to hold onto that block, you should be able to sale it pretty easily. Many have found those early 360s show very thick cylinder walls on the major thrust side during sonic testing.
 
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