Wrist Pin Questions.........

90XR7Cougar5spd

Registered User
I have a few questions to ask, First off, the wrist pins, the part that goes through the piston, Its supposed to move without any ummm "binding up" i guess you would say, all the ones i pulled out of my motor tonight but one dont move as easy as i think it should. Although the one that moves really nice is like butter. Should i go ahead and replace the rods and pistons too or are my old ones alright???? BTW, pretty much all my rod bearings in my motor was trashed. If i didnt pull the motor and tear into because of the knocking, it would have not lasted much longer..... I will post pictures as soon as i can figure out how to post the damn things...


Thanks
Derek
 
If you are going to machine the block you will need new pistons. Always check your pisoton to wall clearance to find out if its too loose or not. I can not remember what is the tollerance but I be you can find it from someone on line here. For your rods, the ends are bushed if the pistons are full floating. I dont thing the pistons in the SC were though so I dont know what you are talking about when you say the wrist pins move freeley unless its the piston that moves freely on the pin. In any case the wrist pins need to be pressed out by a machine shop if you are replacing the pistons. The only reason you would need to replace your rods would be if they had bent, you were going to make SERIOUS (above 400) hp, or if you spun a rod bearing. From the sound of your post that is a good possibility. Have you found the other bearing that disappeared in your engine yet?

Chris
 
Yeah, i found the other rod bearing, its in the bottom of my oil pan in really really small peices, That is where it went. Crazy stuff huh. I talked to a guy i know that has built several motors in his time, hes like 60, and he said that he has seen the disappearing rod bearing before. And what i mean by the movent, is that when you move the rod from side to side, like it was traveling on the crank, there is a little resistance, not much but a little but, i was wondering it that was normal....


Thanks for the help

Derek


BTW, Im pretty sure that the rod is trash, and i KNOW that the crank is trashed, I will have pics up as soon as i can figure out how to downsize them
 
If the bearing spun, the rod is trash. Plain and simple. I am still not sure for your second part of "side to side". Is that flopping the piston from one side to the other like the top forced this way / and then floppin it this way \. Or do you mean actual side to side movement. Either way it shoud be fairly easy to move and the weight of the piston should be able to move it.

Chris
 
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