I did a cam swap on my 2014 Chevy SS this week end. I went with a stage 2 TSP setup with new Gm oil pump, 3 bolt timing set and 7.425 hardened push rods. Vehicle fired off fine but we noticed very little if any oil being pumped to rockers via lifters. went with 5w30 oil and ac Delco filter. checked oil pressure via scanner we had 38 psi at idle and building to about 55psi at 2k so I pretty sure the o ring on oil pump that seems to be a common issue is not the problem. we did some checking and the oil shows no aeration, we did a filter change and oil change to VR1 20w50 unfortunately no change. We determined though that the pushrods may be too short. I failed to measure the length with a checker and based on measurements we feel we may be up to .050 off. Our theory is that the PR's being too short are not plunging the lifters enough to force the oil up the rod and on to the rockers. Can anybody chime in on this.

 

No, not that. That whole "theory" isn't consistent with how the system works. 'Plunging" the lifters to "force the oil" is not fact.

Doesn't take very much oil up there to keep everything happy, regardless.

I'd suggest you go back to the correct oil weight next change.

How did you come up with the 7.425" plan? That's longer than stock, not likely to be too short.

 

based on pushrod length calculations using preload this is how you come with a shorter than called for pushrod length. we ran the 5w30 at first then based off what TSP uses for break in oil on new ls3 crate engines we decided to try an 20w 50 for break in only. we never intended to keep that viscosity for very long . we were diagnosing a problem and we were looking for change in how the dynamics of situation was shaping up. and I was under the understanding that the pi hole in top of the plunger of the hydraulic lifter does feed oil up the pushrod hole and dribbles oil onto the rockers. What is your explanation RBo4av, how does that work?

 

Did you change lifters?

 

Yes the hole in the lifter does indeed feed oil. That much is correct. But no, the preload (within reasonable limits) has nothing to do with how much is fed.

Ideal preload would put the lifter somewhere in the middle of its travel. Most of the stock GM lifters have around .150 - .200" of travel, therefore a good preload to shoot for would be .080" or so. Won't make any real difference to how much oil gets to the rockers though. All that setting that up correctly does, is to make sure that neither are the lifters bottomed out (which would hold valves open even when they're supposed to be closed), or that there's play in the valve train when oil pressure pushes the lifter plunger all the way up as far as it can go which would make the valve train tick loudly and would give up lift and duration. You wanna be somewhere comfortably in the middle between those extremes.

Easiest way to measure for proper preload, in a simple situation, would be to assemble the WHOLE motor less push rods; install an adjustable PR, and adjust it to JUST BARELY take up all the free slack in the valve train, WITHOUT depressing the lifter plunger; add .080" - .100" to that length; order. Test several valves on each side of the motor, both acoupla int and exh, and make sure there's no outliers.

 

no this is a roller motor not necessary. on the question of changing lifters, well RB04Av I will definitely do the preload check tomorrow and at least verify correct length needed for this cam. I was under the impression known cam packages would have similar known PR lengths.my assumption was that 7.425 where I needed to be. trying to cheat the system some what.and we will further diagnosis oil pressure issue up top. would you be in agreement that if we are building pressure and have more than ample pressure at oil switch. that the oil pump "O" ring horror story is debunked?

 

I just did a cam swap in a ls6 vette. We used a TSP 228 cam. Ran there .660 dual springs with 7.4 pushrods. Preload was around .80 as recommended. Valvetrain sounded very quiet and had great oil psi.

If u have oil psi above 30psi at idle and goes up with rpm thin the O ring is fine. If valve train isnt ticking or sounding crazy thin it should be fine. I would check pushrod length with a checker to be safe.

 

 

I agree w your oil pressure conclusion; what you report sounds pretty much about right. With good pressure and no aeration (bubbles) anywhere, the O-ring is probably in good shape. No problems there it would seem.

Cam prelube won't obstruct oil flow. No need to worry about that.

Doesn't really seem like there's a problem, except possibly push rod length. Which might be OK, or might not, just needs to be verified, and corrected if found out of range.