Bad vibes.

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The most dumbass question of all......are you SURE it's a 360?
 
I just checked out a crank kit on rockauto. They offer two steel crank kits for the 360. Were these balanced the same as the cast.
 
Max1196 said:
The 70 Duster, what engine used to be in it that this 360 is replacing?
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This! My Duster’s 340/727/8.75 combo was replaced with a 318/904 sometime in its past. Whoever did the job used the original driveshaft which is too short for the 318/904/8.75. I had a vibration when moving under power. I learned on FABO that I needed the correct driveshaft which I eventually found locally. That got rid of the vibration.
Good luck.
 
aaronk785 said:
I just checked out a crank kit on rockauto. They offer two steel crank kits for the 360. Were these balanced the same as the cast.
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No they don't. That's a misprint. Steel crank for the 360 never existed.
 
That 2206159 number is a 383 steel crank number.
 
Assuming the cam was simply timed with the sprockets put dot-to-dot, was the crank sprocket keyway at about 1:30 looking at the front of the engine when the sprockets were do-to-dot? Just checking the damper position. The cutout ought to be almost centered on the keyway for that type of damper; a weighted damper would have it opposite to the keyway.

Any possible way that the flexplate is indexed wrong on the crank? When #1 is at TDC, the weight on the TC or flexplate ought to be at about 4 o'clock looking from the back of the engine. The 'bite' out of the B&M plate ought to be at about 10 o'clock.

And yes, all 360 cranks should be balanced the same.

Any cranking compression measurements that you can share?

Do you know the history of this engine? I've seen nothing posted that says for sure 'yes'....There seem to be number of assumptions being made, and some things not answered clearly.... since the most obvious things have not worked, it is time to back up and re-examine every small thing.
 
Is there or should there be a 904 pilot bearing/bushing in the crank, slop in the pilot shaft could cause vibration
 
I had never heard of a steel crank 360 either. But when I saw this I thought ok, maybe. Vibrates in neutral so not DS. Flex plate only fits on one way. Engine came out of a friends van. He said its never been opened up. If the cam timing is wrong im not changing it. Runs like hell for what it is. We built this about 2 yrs. ago. He don't drive it much because of this. I'll check everything suggested. Thanks.
 
Flex plate only fits one way on the hole pattern in the back of the crank.... but that is correct for balancing only if the hole pattern is indexed correctly on the crank. Ditto for the crank keyway position. Production mistakes happen.... so if you don't check, you cannot be sure. Read once about a Pontiac crank where one of the throws was off almost 10 degrees from where it should have been... How it got that way, who knows, but it came from the factory like that and created a lot of problems not found until someone looked at something no so obvious....very unexpected.

It's going to be something and you have pursued the most logical things... so now for the illogical things! And just because it came out that friend's certain van does not mean it had not been touched.... sounds like it is 'open season' for anything on this one. LOL

I do hope you find it.... I never found a vibration in an old Econoline van.... I looked and looked. I just did not know about enough about these things at that time, and that was a coupla decades before the internet...

Other random thoughts:
  • Input shaft on trannie bent
  • Balance weight inadvertently taken off of the neutral balance converter
 
We will put it on the lift when he has time. I get what your saying about the crank . I'll check the positions of the flex plate cut out and balancer weight. I'm not the only one how has helped on this. We're all out of ideas. It has to be something like you said. Thanks again.
 
I know the flex plate only fits one way per bolt pattern. But what would happen if plate would be flipped. Would that put weight 180* out? Or would bolt holes not line up?
 
It would not work if flipped, for several reasons.... but if it could be, the irregular spacing between bolts holes would make the holes not all line up.

aaronk785 said:
We will put it on the lift when he has time. I get what your saying about the crank . I'll check the positions of the flex plate cut out and balancer weight. I'm not the only one how has helped on this. We're all out of ideas. It has to be something like you said. Thanks again.
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Yeah, it's like the guy on here about 6-8 weeks ago with the back surface of the block not machined square to the crank axis..... it was off by .042" from square at one point on the bellhousing surface.... a 'Monday' block. The internals sound like 360 LA internals but with the incomplete history on the engine... who knows for sure?

Any chance that there is any confusion between Magnum and LA parts?
 
Thanks for all the ideas everyone. Weather wont break here, so might be awhile before we can get to it. I will let you all know what I find. I guess someone could have put a magnum crank in it at one time. I'll pull the pan and get numbers to make sure.
 
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