SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: fordfan on June 02, 2009, 11:01:22 PM
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Hey guys, so i need some opinions on my problem. So i pulled the 460 out of my boat to replace a bad flex plate i put a balanced plate on changed out the freeze plugs and put new spark plugs with a new distributer cap. I put the motor back in and now it is shaking when its over 2000 rpm. all the cylinders compression checked between 125 and 130 so there is no dead cylinder and the pump had no problems before so i can't see why it would be cavitating..
help i am supposed to be on the water this weekend.
thanks guys
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Hey guys, so i need some opinions on my problem. So i pulled the 460 out of my boat to replace a bad flex plate i put a balanced plate on changed out the freeze plugs and put new spark plugs with a new distributer cap. I put the motor back in and now it is shaking when its over 2000 rpm. all the cylinders compression checked between 125 and 130 so there is no dead cylinder and the pump had no problems before so i can't see why it would be cavitating..
help i am supposed to be on the water this weekend.
thanks guys
Sounds to me like either the PTO or the driveline did not seat all the way, worth rechecking IMO..
You say "balanced" flexplate, did someone drill or weld it to balance or do you just mean nuetral?
Could be a stiff U-joint also, did they feel smooth?
good luck!
GT
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Make sure the balancer is on the right way.... and yes I have made that mistake ;D
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the flex plate is a napa balanced which was just a weight welded on it
the u joints felt fine i didn't look at them in depth :banghead:
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the flex plate is a napa balanced which was just a weight welded on it
the u joints felt fine i didn't look at them in depth :banghead:
HMmmm, I would have bet money the 460 was a neutral flywheel delio (I don't do Fords).
Was the old one weighted?
GT
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Double check the firing order on the cap ;D I think that's where the problem is.
We used to have a similar thing happen with U-Hual trucks (460) during a Preventative maintenance when some pinhead changed out a cap and rotor sometimes, and I can't remember exactly which they would reverse. PM'd a buddy who has my old job there, if he texts me back I can tell you which ones.
HMmmm, I would have bet money the 460 was a neutral flywheel delio (I don't do Fords).
Was the old one weighted?
GT
460's are, for the most part, internally balanced, and the flexplates will only go on one way (Hole spacings force this)
Ray
Edit: Sorry about the pin head comment, wasn't directed at you. The guys who used to do this routinely did this 5 times a day every day and even the mechanical bays would miss it and it would end up in one of my QC bays to diagnose and fix it. You don't do this anywhere nearly as often and is an easy thing to do. Sorry if that came off the wrong way, I'm tired, lol
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My son put a new flex plate on his 460 and got a vibration. Guess what. His had the weight
welded on it too. He ordered one for an internally balanced 460;
I pulled the engine to check it out, that was the only thing I saw strange. We put on one of my
spare original ford plates and no vibration.
None of my original plates (netrual balanced) have a weight welded on them.
Hang it on a nail like you're balancing a mower blade and see if the weight wants to find the bottom.
Ours did.
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if you have the hatchet weight on the front of the crank you have an external balance crank and need the external bal flywheel. if you just have a spacer behind the crank balancer you have an internal bal crank.
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first off want to thank you guys for the help! after reading the ideas on it being the flex plate i got to thinking, since i spend my working hours sitting in traffic, and realized that you guys were right it was originally a nuetral flywheel and i bought a balanced one, since i dont pay attention. went and got a neutral one today and am going outside to pull the motor and put it on right now. should be able to go to puddlestone tommorow and test to see if that solves the problem. thanks again.
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ford switched from internal to external in 78 I would think it is the flex plate if that is the only thang that changed.
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Simply put, if your old one didn't have the weight on it, then you have an internally balanced rotating assembly, which means you have to run a neutral balance flexplate (one without the weight on it).
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Thread jack... Hey jet where ya been ??? havent seen ya around these parts lately :sly:
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Thread jack... Hey jet where ya been ??? havent seen ya around these parts lately :sly:
Hangin' out on Performance Boats...I stop in around here once in a blue moon ;)
Hey Brad...you should have Dilworth push his Jet Dynamics business around these parts. Rumor has it that guy really knows his shit.