hey everybody, ive got a 79 bronco with a 351m. we recently rebuilt the motor, which usually has a happy ending, right? not this time. i was driving it during the breakin period and i noticed the oil pressure would not last very long. my answer was to buy a high volume oil pump. here is where things get juicy. when i took of the oil pan, my dad noticed cunks of copper in the oil pan. upon further inspection, we found that the rear thrust bearing was shot. after puling out the motor, again, we found a pilot bearing still in the crankshaft. too bad my tranny is an automatic, not a manual, otherwise id be ok. the guy who did the machine work on my crank used the bearing so that the crank would have something to turn on when he had it in the metal lathe, but he forgot to take it out. that was one big oops i think!

anyway, my question is about the oil pump. a mechanic i talked to used clevlands for pulling motors, and he said that the oil passages have great flow up to the heads, but not back down, so he had to put in a coupl of restrictors in the block. im not sure if i need to do this because my motor isnt going to be spinning at 7500 rpm. do i have to do this or not? and is that nice high volume oil pump just going to compund the problem? any help would be great. thanks!

 

If you don't think you need as much restriction enlarge the opening a bit but you should have them, It will keep the bottom end lubed up! Where as if it did get starved
You are definately looking at another rebuild!! If the valve train got starved and you werent turning high rpms it has a better chance of survival! I would cut open that oil filter and see what landed in there, That will give you an idea of what was swirling through the oil, passing all the bearing surfaces!!

 

I wouldn't restrict the oil galleries to the cam you have to run a soild lifter cam if you do this, I have seen people who run an external line from the oil gallery down by the oil filter to the one behind the intake manifold to help with this problem, but i don't feel either one should be necissary on a street motor. I really don't think that the pilot bearing would hurt any thing it shouldn't have any affect on anything internal, I don't know how machinists find a cranks ceterline when machining them but if he just put a live center in a pilot bushing it sounds less than accurate. I would recomend running an after market oil pump drive shaft (actually I always do even with stock pumps) with a hv pump I use ARPs they are cheap insurance, I pulled a 289 apart and that factory drive was twisted in half thus why it needed pulled apart.
-Johnboy

 

the pilot bearing was sitting in the spot where there torque converter would sit on the crankshaft, so when the fly wheel got tightened to the converter, it flexed the flywheel and pulled the whole crank assembly toward the rear of the motor. the fly wheel was cracked and the thrust bearing ruined as a result. there was also some scratches and heavy wear on the crankshaft, so thats ruined too.

 

well toss that engine. Long block time. I would not restrict anything. your running stock, and your problems were not from starvation, but from mechanical forces of the wrong parts. High volume does not equal more pressure. just more volume. I would use a QUALITY stock pump and be done with it. Most damage is from startup and shutdown. If your concerned with damage, then look into a pressurized oiler.

Here is more oiling info than you need to know ..LOL..

OILING