|
|
|
|
Original Message
|
| long detailed note on original 428 balance |
| By hawkrod - 02/10/2002 1:02:51 AM; IP 198.81.16.171 |
| more info on points #1 and 4. from the factory ford does not use the balancer or the flywheel to adjust the weight of the rotating assembly. first the harmonic balancer is balanced to zero by the holes you see. sometimes there will be more or less meat that needs to be removed to make it "zero". second the flywheel is balanced to have a certain amount of weight at a certain spot that ford determined that a 428 needs. then the crank is spun using the predertimined standards and weight is added or removed from the crank. by doing it this way the parts are interchangeable in an assembly line process and thus no added expense down the road. to simplify this, all 428 cj flywheels are balanced the same but they may have more or less weight removed to get where they need to be due to casting density, flaws, shift, etc...so some will have more or less holes and machining. where it gets really confusing is that a 428 cj flywheel is balanced different from a 428 pi flywheel! many people think they are the same and while they can be interchanged they are balanced ever so slightly different. that is why ford had different flywheels for what appears to be an identical part. they also did this on hipo 289 and boss 302 flywheels (i learned this from someone who was able to show me engineering specs) the differences are so minor that the vibrations are within acceptable limits and thus not an issue but at 7000 rpm in a boss i am sure it would show! also when the piston weights are changed the balance changes so that is why there are so many different 428 cranks. they had different balances for the changes in piston weights on regular CJ's and for piston and rod weights on SCJ's so that is why there are actually 6 different cranks for 428's (doubters stick with me) there are two totally different 1U cranks! one is a 428/428PI and carries a C6AZ part number, the second is the 68 1/2 and early 69 before the november change and carries a C8OE part number (the only reference i have for this is an august 68 parts book), after the november 68 piston change the cranks are usually 1UB (but i have seen 1U's in #'s matching cars), the 1st SCJ crank is 1UA, then in late 69 they changed again to the B and the A cranks. the parts books break all of this down by production dates and it is my understanding it is all tied to the piston changes. then the last odd thing i will add is that the non-SCJ 428 cars with an automatic all used the same flexplate (except the early 2 piece ones) and i have never figured out why it was necessary for the sticks to have two? so the last word would be to have your engine balanced by taking or adding weight to the crank only as that will, in theory ,allow you to swap balancers and flywheels without affecting balance (at least not significantly!). hawkrod (i knew that i should have marketed a trivial pursuit for Fordophiles!) |
|
|
This thread, so far...
|
|
|
|
Post A Response
|
|
|
|
|
|