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Motor damage from wrong flywheel?

7K views 12 replies 7 participants last post by  sackman9975 
#1 ·
I know for sure I have the wrong balanced flywheel on my motor. Someone reused the 0 balance flywheel off the 4.9 when they swapped motors to a 302 (which in my case requires the 50oz imbalance flywheel). I'm not worried about doing the swap but what I am worried about is what kind of damage might have been done to the motor during the time they PO drove the truck that way? At the moment I can't tell if there is any unusual knocking or ticking coming from the bottom end because of how bad the motor shakes after you fire up the engine. I guess I'm really concerned about the crank bearings, besides that what else should I be looking for? Rear main seals, water pump issues?? Anything like that?
 
#2 ·
Swap the flywheel and see what happens. You may be worrying for nothing.
 
#3 ·
I hope so but I do know that the PO drove the bko long enough and hard enough that he cracked the bell housing on the transmission (then again that could have happened 5 minutes after doing the swap and getting it running???)

But if I do have to rebuild or buy a new motor it shouldn't be to bad since I'm just going to sell my car and put the money into getting the bronco finished.

Never should have bought a chrysler product in the first place :banghead
 
#4 ·
If your rear main isn't leaking horribly and you still have good oil pressure then the main bearings are probably not gone yet. Change to the right flywheel and keep going.
 
#5 ·
I know for sure I have the wrong balanced flywheel on my motor. Someone reused the 0 balance flywheel off the 4.9 when they swapped motors to a 302 (which in my case requires the 50oz imbalance flywheel).
How do you know this FOR SURE?

My question is, would a 300 flexplate/flywheel even bolt up properly to a 302? There are offset holes on all flexplates/flywheels.
 
#6 ·
I have read many many threads on this site along with others that have said 300, 302, and I believe 351 flywheels have an interchangeable fit however they don't have the same balance weight. And I know the harmonic balancer is the correct one for my current engine.
 
#8 ·
I have seen the wrong balance take out an entire engine block. Very quickly too. My buddy bought a RX-7 with a 302 in it and the PO put a neutral balanced flywheel and harmonic balancer on it. The motor had stress fractures in the bearing journals and the caps. The cranks was cracked and the rods were damaged as well.
 
#10 ·
I would verify that the firing order is correct. Also verify that all fuel injectors are working properly/plugged in. Maybe do a compression test too.
 
#11 ·
Never thought about the firing order because it is hard to start sometimes and doesn't like to idle that well but then again it's kinda frustrating working with a carbed motor. I forgot to mention that when they did the swap they went backwards and went with a carbed 302.
 
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