i wonder how much of the mysterious lt1 spun bearing problem that some people have is a result of to much oil going to the lifters at high rpm on stock shortblock cars? some people never have a problem, but others are taking out rod/main bearing left and right. not all of these people can be installing the cams improperly.

my theory is that as rpm rises, the demand for oil to the hydralic lifters overcomes the capacity of the stock oiling system and the main/rod bearings are the ones that get starved. this seems like something that a HV pump would solve, but i think that would just serve to suck the stock pan dry and the problem would persist.

this theory also jives with the fact that it happens to higher mileage LT1s because as the bearing clearances grow more oil flow to these areas is required, espeically when increasing the rpm range. i think a bandaid for this problem is thicker weight oils. i think the real solution (while maintaining a stock pump and pan) is limiting oil flow to the valvetrain and running a solid roller cam.

 

i have often wondered about this mystery too. Your theory makes sense but a solid roller setup would kill the driveability of a hydraulic setup. For street use i think that a new cam install needs to have bearings go along with it. When i did mine i figured if i spun a bearing i would just pull the motor and rebuid. And here i am working on a blown 355. Sucks that i got 500 miles out of the new cam and heads and now i haven't driven it for a year.

 

by the time you have an aggressive enough HR to make peak power at 6500 and have a 7K rpm shift point the driveability difference is negligable IMO. the hydro lifters are gonna be real hungry for oil at that kind of rpm, couple that with .0025-.003" main/rod clearance and you are going to have an oil hungry engine.

i think the the only thing new bearings are gonna do is marginally decrease the flow requirement, but as those bearing clearances grow the problem is likely to show itself again if the stock pan and pump havent been upgraded.

 

so you are saying if you do heads/cam then do hv oil pump/hv oil pan? To save a motor that is not a huge chunk of money so it would be good insurance. I'm thinking about a 7 qt pan and a hv pump on my blown 355 build.

 

thats my theory. but i would still run a thick oil (20w50-sae30) with the HV pump and higher capacity pan for extra insurance w/ the looser bearing clearences and the thirsty hydro lifters. canton makes a 6qt pan for lt1 f bodies. its pn is 15-242T. who else has lt1 oil pans?

 

yet another reason NOT to spin your car so high... 6200 rpm on an OCCASIONAL basis is what i'd say.....

as to the oiling problem, what about using a higher capacity oil filter? Though I'm not sure how well that'd work, atleast its more oil :P i believe Fram makes one, i **THINK** Mobile makes one too....

 

i run ac delco 1218, its a 1qt filter. i dont think its a problem with spinning the rpms, its just preperation needed to spin the stock shortblock. this oiling system thing is just my theory right now. but its a pretty educated guess based off a buddy with a stock shortblock NA 5 liter who kicked the bearings out after revving the **** out of it with HR cam and a stock oiling system. he went solid roller, restricted the oil flow to the valvetrain and it hasnt been an issue since.

 

i'm still thinking the solid roller setup is not the answer to the problem. There has to be another way around this. As far as hydraulic lifters are concerned, the market is very slim. The comp r's seem to be the only performance lifter but they seem to have their share of problems. I don't really think the lifters are the problem anyways. They just couldn't require enough oil to run the oil pan dry. Does anybody have the exact figure on how much they actually hold?

 

Lifter's are not a problem. The thin oil,extra RPM's with thin oil and the quality of brg GM put in to start with.Stock rod bolts are another problem.They stretch and cause the big end hole to get larger allowing the space for brg stack.
The GM brgs can't take the load also and thin oil with wear makes for a low oil situation at each brg,causing metal to metal contact and a spun brg.With the wear clearance and thin oil there is to much gap for the thin oil to stay in the brg and the pump will not pump enough volume to compensate

 

does the oiling system feed the mains or the valvetrain first? my concern for extra flow comes from the fact that as the bearing clearences open up with wear (as mileage gets piled on) the oil flow requirement, especially at high rpm goes up as well. and if the lifters are taking all the flow from the mains then there maybe a problem. is this even a concern?

 

the joe schuebreck (sp?) has some hydraulic lifters that he modifies and reduces the plunger travel from .400 to .010......so its basically a solid lifter for classes that require a hydraulic. if its just the thin oil then kickass, thats an easy fix for most people. im a big believer in the thicker oils, especially since after some mileage the bearing clearances open up.

 

I have been running the stock pan for years with my mellings HV oil pump and it works perfect


oil press is 45psi at idle and 65 psi at wot

 

how high do you rev it?