Thread: Breaking in new cams, different than normal?

To all those people who think cam break in is not important.

http://www.sr20-forum.com/showthread.php?t=5052

In this case the problem is not the cam break in. The rocker had score marks on it. The installer did not condition the rockers before installing the cam. The wear/ score marks transfered on to the cam.
Old school rule of thumb, new cam new rockers. Well knowone her buys new rockers. So they need to be be conditioned with emery cloth and scotch brite. Then follow the JWT cam berakin procedure.
The purpose for raising the RPM (not Revving the motor) to 2000rpm and holding it there is to build heat to allow a wear pattern to be established.
Cams cannot be effectively broken in at idle.....

SERacer. I have the instructions sitting in front of me as I type this. No where does it say that you need to recondition the rockers. I am gunna try and phot copy it, I followed the exact way JWT says to do.

My oem stock cams were perfectly worn so idk why these S4's did this.

SEracer, could you elaborate on that process a little? Thanks..


Dudeman

ive always just thrown my cams in and went, i dont let it idle for any more than a couple seconds just to make sure timing is still correct and everything is fine, i then take it out and drive it. hell my S4's i drove them until it was warmed up and then let the fun begin. I just recently took them out when i had to change over the motor and they were spotless to say the least, still looked new after 5k miles on them. Not a single issue at all.

I never use assembly lube either, i use the same mobile 1 synthetic that i put in the engine, ive heard some weird things about assembly lube. it gets lubed with oil so why not use oil. I pour oil on the bottom half of the cam bearing then coat the entire cam with the oil making sure the cam bearing areas get completely covered then install the cam caps. never had any problems and ive done many many cam sets on SR's more than i can remember,

He never said that the JWT instructions said to recondition the rockers. He just said to recondition them, THEN follow the JWT instructions

(My oem stock cams were perfectly worn so idk why these S4's did this.)

The rockers have microscopic wear from metal to metal contact (cam & rocker) no matter how clean they may look, there is wear. You can sometimes feel the wear marks with your fingernail.
New cam old rockers or vice versa, in order for them to work together a new wear pattern has to be established.
By conditioning the used rockers or used cams with fine emery cloth you are smoothing out these microscopic imperfections.

Dont worry you are not going to wear down the cam or rockers with a light brush with emery cloth. The super hardened steel will not be damaged.
Back in the day when we were building Toyota 3T and 20R motors. The V-8
machine shops would calculate spring pressure based on V-8 formulas. So the spring pressure would be too high. We did not know that at first. We would see premature cam wear or scores on the cams. on some motors.

Thanks to Nissan's design, this is minimized to a not so damaging out come.
With this knowledge I have always practiced good engine brake in procedures.

Thanks for your information on this.

I stand corrected, and will chalk this up with my memory banks.

What is your opinion on installing used cams, then?

I am getting ready to install larger cams in the near future, and they have about 5K miles on them. Should I still run the emory cloth over the rockers, just to be on the safe side?

Thanks.

When you are ready, with the old cams removed inspect the rockers carefully determine if any need the emry cloth or just some scotch brite. Take care not to get any debree into the engine. do the same with the cams. Use assembly lube on the cams and rockers and cam caps, just enough to coat each piece. assemble evenly and torque to specs. Follow the brake in procedure and have at it.

This is true for any motor, roller rocker motors, are not as critical.

The reason for reving to 2k has nothing to do with the lobes contacting the rockers. It's about the load being placed on the end of the cam where the cam gears are. The stress is the highest on that end of the cam at idle, reving to 2k lessens the load. Check out this or last month's Sport Compact Car, they explain it much better than I can summarize.