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

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

Double check the firing order on the cap  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

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.

ford switched from internal to external in 78 I would think it is the flex plate if that is the only thang that changed.

Thread jack...  Hey jet where ya been havent seen ya around these parts lately