Cam Wear

[240260280z]

L24 fresh rebuild with Schneider springs, medium Delta regrind Cam (internal oiling), and new reground rockers ate the cam after ~ 2000mi. Very good oil pressure. Assumed bad metal, straight 30 break in oil followed by synthetic oil played a part.

After removing and resolving the above...

A new medium Schneider Cam with new rockers was installed 1,500mi ago and lobe 1 is starting to show wear. (on the back side of the lobe). The oil is dyno with zinc additive.

I am now guessing that the Schneider springs and/or a partial oil blockage to the head are to blame. The springs were extremely difficult to install due to their high spring constant and the oil flow out of the cam when cranking using a remote starter seems less than the old spray bar that I have seen many times.

Any ideas?

My current plan of action is:

1. Try a new oil pump and crank with starter to see if oil flow improves.

2. If no improvement then take off the head:

- inspect oils passages in head

- clean and inspect contents in oil galley between filter and oil restrictor in top of block

- install regular springs and a Nissan Cam with Nissan Rockers.

This car is going to NH next week so no time to mess around.

All help, advice most welcome.

Edited July 30, 2013 by Blue

[zKars]

oh oh. I'de be removing the oil pump drive spindle and driving the pump with a drill and 3/8 rod with a flat ground on the end while watching the oil flow from every cam lobe. That way you get higher pressure and flow rate than while cranking.

Remove the rockers so you can see them all flowing (or not) at once. Judge from there.

Can I rush ship you a fresh stage 3'ish stock regrind and more fresh rockers?

Hmmm, never thought of offering a cam rental service before....

[240260280z]

Thanks Jim! Good ideas! I'll try them.

Thanks again for the cam offer. I'll see what I have in our club's barn of parts first then may circle around for the stage 3 cam

[madkaw]

I would second the advice above. Drive the oil pump with a drill and watch the oil coming out that way.

As far as springs, I run the complete Schneider kit, springs and all and I have no bad wear. It only takes a second or two to do that kind of damage without good oil flow.

Too many disasters here lately, that sucks.

Good luck

[Zed Head]

Maybe your subconscious added emphasis when you wrote, but the thing that jumps out is the spring pressure. My understanding is that the spring rate, spring height and the distance between seat and retainer (giving preload) will determine initial (base circle) pressure. Maybe one of those three things is off.

[Diseazd]

Hi Blue.....Did you set up the rocker geometry with the correct lash pads? Pull that rocker arm and check to see that the wear pattern is centered. It could be that the cam is off the front of the rocker slightly. Sorry old boy.....

[jcb]

I hope you are using an approved start up cam lube. Wear like that can start on the very initial engine startup after rebuild if cam does not have proper cam lube at time of install. I have seen this happen a couple of times. Sorry to hear this happened.

[240260280z]

Yup rocker to lobe patterns are spot on and were checked using the marker method.

Clevite rebuild lube was used on the cams undiluted.

[Diseazd]

Did you email a pic to Delta for their ideas? The people at Isky are always very helpful. I would doubt that spring tension caused the problem....Scneider has a ton of these on the market.......Call Eiji at Datsun Spirit, he uses Schneider cams and springs, he might have some ideas or suggestions.

[240260280z]

Thanks Guy, I'll ring delta.

Here are photos of the rocker from #1 Exhaust corresponding to the worn cam lobe.

I also pulled off #1 Intake to compare.

Both have good wipe patterns.

I notice a ridge on the plug side of the pattern on both rockers. It is easily felt with a finger nail and can be seen. It is more noticeable on the worn one. There is no ridge noticeable on the distributor side of the wipe patterns. So it seems there is more wear on the valve return portion of the cam's cycle.

I also observed great oil flow after cranking but it seemed longer than normal for it to appear. Any ideas if there is anything related to this? Only Purolator and Wix filters were used since new.

The rockers in the photo are Delta regrinds. I have other used stock Nissan rockers i can throw in if that may be the culprit. Yes/No???

Edited July 31, 2013 by Blue

[240260280z]

Delta thinks it is the springs since they are the common part and that the break in process was correct yet the cams did not service the break in periods. They recommend I use only one of the Schneider valve springs for the next break in.

I'll put a stock cam, springs and related components in to get to the ZCON.

Edited October 11, 2014 by Blue

[Diseazd]

Blue....It looks like a defect in that rocker.....is that an optical illusion or a little defect just before the bright wipe pattern? I'd try a new rocker and see if the wear transfers to the new rocker. If not, just run it.