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c4 tranny ? thrust bearing ?

2K views 7 replies 4 participants last post by  st pete chad 
#1 · (Edited)
ok i have a 351w stock bottom end motor with victor jr heads,f cam spyder style intake with a 76mm turbonetics turbo.so a few weeks ago the motor takes and shit.i was thining it was from detonation but once i took it all apart i seen that the crank shaft was walking about a 1/4 if not more.so i finish taking it apart and i see the thrust bearing is cracked and wore out like the crank was being pushed forward.i was told its go to have something to do with the convertor.uts a PTC convertor and ptc said its got anti ballooning plates but i dont see them on the side of the convertor.so i called them and they say its on the top of the convertor and the bottom guess made into the case. some people are saying the converto is ballooning and ptc is saying no way that it is ballooning with it only making 580 @ the wheels.anyways im about to build a new motor with a s480 but dont want to untill i can figure out what caused the crank to be pushed forward.anyone else ever deal with this if so let me know what it was or might be


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#3 ·
yea im sure it ran lean.at the time i didnt uderstand why or how because its been the same boost for the past year but as i was taking the motor apart i noticed the timing chain had alot of play.well after taking it all apart thats when i seen the crank shaft was walking real bad and was pushing forward and stretched the timing chain so i guess it could have jumped a tooth and was now running more timing then what it was tuned at plus running 93 pump gas on 16psi guess it was just a matter of time before it blew up.i just dont know why the thrust bearing was wore down and cracked then dug into the crank
 
#6 ·
I run a PTC convertor and have no porblems with the thrust bearing. Did you set your convertor/flexplate clearance when you installed the trans? What was the main thrust bearing clearance when the motor was fresh? When I pull my motor and check it during rebuilds, it's always virtually the same clearance as when the motor was assembled.

Make sure your crank gets reconditioned correctly. There is a specific pattern required for the thrust bearing face on the crank.
 
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