Heres the story.

Just put in a vortec headed 355. Its got a brand new: crank, bearings, rings, blah blah (rest in sig). I built it myself but I don't think the clearance for the main bearings was tight enough becuase when the car gets to full temp the oil pressure is around 7-10 psi and every now and then the motor makes a light nocking (Its not consistant though and only at idle).

I just developed a new problem. I have a rocker chattering but I go to tighten it and it quiets down then starts making noise again. Its as if the lifter is collapsed but they are new comp cams lifters. I'm not sure if this could be because the very low oil pressure or not. Oil does not come out of the rockers at idle (it barely oozes out) at full temp. Any ideas or suggustions.

This motor needs to last a few months. I was thinking of getting a solid cam. Then I wouldn't have to worry about collapsing the lifters due to low top end oil pressure. Would this be really stupid?

Thanks,

 

You know for a fact that you have low top end oil pressure? I know that the little valves inside the hydraulic tappets (either solid or roller) are operated by oil psi, as you stated. However, those valves inside the lifters can also collapse due to incorrect valve spring pressure. You CAN make the switch to a solid cam/lifter setup. That will eliminate the lifters collapsing due to the lack of oil pressure. However, that doesn't SOLVE the issue of low top end oil psi (if indeed that is what is causing your lifters to fail.) Are you sure you are running the proper spring pressure. I have never heard of lifters collapsing due to low oil pressure.

The things that i know that would affect oil pressure/volume:

• Oil pickup mounted too high (issue of sucking dry, not pressure)
• It could have even fallen off.....the pickup that is
• oil plugs are missing? (i think thats what they are called)
• cam bearings installed incorrectly (would effect oil PSI BIG TIME)

I have seen the results of bad cam bearings...and low oil psi is a result....by chance was the block cleaned via bead blasting or other form of high abrasive?

 

why do you think the main clearance wasn't "tight enough" and not know what it was? didn't you check anything? if the rocker won't stay adjusted try replacing the rocker nut. i'd put a mechanical gauge on the engine and see what you really have and not trust the factory gauge.

 

i agree with ede, what was the main bearing gap? if you dont know that, dont plan on it lasting a few months.

 

Yes. oil is barely oozing out at idle. Most of the time not at all.

LOL. Not being a dick but you must not know the dynamics of a hydraulic lifter. Yes the spring pressure is right. They are the stock vortec springs! I doubt the open seat pressure on these would be too great for a set of comp cams lifters. Not a large cam either.

Add loose bearing clearance to that list.

I did check but It was the first time I've used a plastigauge to check. Usually I just use my micrometer. Thats my fault for not double checking. The plastigauge crushed but I think It was too thick to begin with. I noticed the bottom end was easy to turn over with everything buttoned up.

its not the rocker nut coming loose. I held the ratchet on there the whole time. Could it be a collapsed lifter. I need to do a compression check to make sure its not a bent valve. I have a mechanical gauge on there now. my stock sender broke.

 

on those vortecs....are the studs pinned or screw in?...they could be pulling out

 

hmm. Didn't look at that. I'll check.

 

One other thing to look at; you said that the rocker nut isnt loosening. Are the tops of the rocker studs even (to see if one is pulling out) and even more important- compare your "problem" rocker to the others. Does it seem lower? You could be bending a pushrod or worse- eating a cam. I have had two cams go flat in my years. Its usually easy to see when you look across the rockers and see that one low one! If its lower, pull the pushrod and spin it in a drill, not bent??? Then its probably the cam.

 

yea, you are right. David Vizard's camshaft and valve train book has taught me nothing.

maybe what i meant was i have never heard of it happening in person. maybe, i cant quite recall. have i heard that it possible? the world may never know.

 

the plastigauge looked too thick? did you measure the thickness after you crushed it?

 

Well books are great and I encourage everyone to read (as I do myself), but with that being said: experience is the greatest teacher. I'm not very old but I've been around the automotive venue since I was a kid. I'm a certified mechanic now and still have a long way to go.
I've seen flat tappet lifters collapse and chew cams to death and come to find out...the block was originally a roller! Who would have thought.

There are different kinds of platiguage with different ranges. These are determined by its color. There are red, blue, green etc. Mine were red I think and the range was from .005 to .015. I could be wrong but thats what I "remember". Usually I try and keep the mains around .002. Of course if the plastiguage was really thick then It will crush but I couldn't tell at what clearance it crushed at.

 

sounds to me that a stud is pulling out!!!!!!!