hi guys, want to double check - iam about to order new flexplate /flywheel ,problem vibration when running ,i have a casting #eoae d3c block 80 model 289 block in a 1965 mustang ,looks like someone has tried to work things out b4 ,the trans is a c4 with a 160 tooth flywheel ,my guess is they changed the motor for what ever reason to the 80 model and bell housing on the trans now a6 bolt bell housing and used the original flywheel with 28 oz weight and the 1980 engine needs a 50 0z weight so what i was thing to order is a 157 tooth and 50oz flywheel do u think this is right ,cheers dave

 

That block could have either imbalance in it's crank. Check the crank casting numbers to make sure as to what it actually is. The block numbers should never be used to determine the imbalance of the crank. The imbalance was changed sometime around 1982 (the exact date is fuzzy to everyone, including Ford) then they changed the rear main seal to a one piece seal somewhere around the same time frame.

 

will crank casting be visible when box is out or will i need to take pan off as well

 

I ran into this in my 78 . Got an 80 model engine free , a story in that , turned into a nightmare ! 84 crank , balance issue, sorted the balance . Now the other issues show up . Kid lined up the ring gaps , in a straight line ! New cam , bearings wiped out ! 4 bent valves on the " new " heads ... New pistons . I go through it and sort what I " thought " were all the issues . The kid only ran the motor for 2 weeks . Now , I have a wrist pin tapping . Well I'm going to build my old engine . 6k miles with the tap though ... still driving it .

 

Only sure way is pull the oil pan and read the numbers on crankshaft. Balancer, crankshaft and flexplate have to be the same counter balance.
For future reference, your E0 engine is actually a 302/5.0L not a 289.

 

Yea, you'll need to drop the oilpan to check the crank numbers. If I recall correctly a 2MA is the 50 oz crank. 2M is the 28. The size of the counterweights is also an indicator, but only if you've got one or the other in hand to compare it too, or have worked enough with these to tell the difference without another crank. The E0 blocks were used for 4 years in production. If it's got a one piece rear main seal, then it's a 50 oz crank.

 

what if i id the flywheel to see what oz weight it is and replace with opposite

 

You can play guessing games or do it one time correctly and be done. Do not forget the harmonic balancer. If you can pull a tranny, the oil pan is a piece of cake.

 

I'd imagine a 22oz imbalance would shake the doors off, wouldn't it?

 

Well if you're running an automatic trans, then no, unless you have a known flexplate to compare the size of the counterweight to. If it's a Ford flywheel (for a manual trans) then you can I.d. it via the engineering numbers cast into the flywheel. A pre 1980's wheel will be a 28 oz. A 1980's wheel will be a 50 oz. You also need to check the balancer to see if the outer ring has slipped, you can do this by getting the #1 piston at TDC then looking at the timing marks to see if it's aligned to TDC on the balancer. If not then that's likely your problem.

 

I had to change the drive plate & harmonic bal. on my 302 while rebuilding. The machine shop swapped me out a .010/.010 crank so I had to take the crank, harmonic bal., drive plate, rods & pistons to the engine balancing place.
Will probably be about a week or two before I know how it runs.
TractormanBill

 

If you had the correct imbalance balancer and flywheel/flexplate you didn't have to have the rotating assembly balanced. Not that there's anything wrong with doing so, but it's not an absolute necessity. Even having it balanced, it's only 100% balanced for a certain rpm range.

 

Thanks Bad Dad and we will see how it runs.
TractormanBill

 

yep, almost 2 lb imbalance would rattle the doors pretty good, at idle speed

 

argh, some people's kids