billla

Big difference between OEM-style cams and springs, even factory high performance ones, and modern aftermarket cams and springs. I can't think of a single cam vendor that doesn't recommend a similar 30 minute break-in process. As an example:

http://www.compcams.com/Base/pdf/Fla...chBulletin.pdf

http://www.cranecams.com/uploads/breakin/548e.pdf

http://www.edelbrock.com/automotive_.../2000/2102.pdf

I follow this process, adding in pre-oiling as a free security blanket, and I've never lost a cam. Folks should be really careful taking "expert" advice that directly counters what the manufacturers specify...

Tim H

Well then your doing it wrong.
The lobes aren't getting polished to the lifters correctly.

terry82

you dont have to go that far .but there are places that you can drive the car at that rpm.that was the question.

jb78L-82

I have also been wondering about the breakin subject where GM and other manufacturers are concerned as well! I seriously doubt that GM ran there LT1 engines for 20-30 minutes after they built the motors back in the late 60's/70's. Common sense dictates that the first few seconds after startup would be crucial to lubricating a new part such as a cam, just like it does where engine wear is concerned. 90% of engine wear occurs during the first few seconds especially in a cold engine which is one of the reason that most manufacturers require very light weight engine oils in newer engines. I can understand priming the engine before startup with a new cam since it takes a few seconds to get the oil circulating (longer if the air temp is cold) and that period could be crucial.

Which brings up another issue: If someone decides to change the cam in their engine this winter and the garage is 40 degrees, how smart is it to start the engine and rev the motor to 3,000 RPM immediately for 30 minutes? As someone all ready suggested, could that procedure contribute to cam failure?

Lastly, I personally do not think that a mild to moderate cam profile requires such a procedure. I am not an expert but I doubt when I do my cam that I would follow this procedure exactly since there is potential for other problems following this requirement.

Has anyone heated the engine oil BEFORE putting it in the engine to reduce the viscosity and besides ALSWAGG who does not follow this procedure recently and had no issues? Just curious!

terry82

why 3 thousand rpm .why not 2 thousand .what happens at 3 thousand?why not idle ?is that where you get the best oil pressure?

zwede

You need enough rpm for two things to happen:

1) The lifter needs to rotate. If the lifter "gets stuck" (doesn't rotate) in the bore the lobe will wipe.

2) the only oiling cam lobes get is splash oil from the crank. There's not enough splash oil at idle for break-in.

I don't think 3000 rpm is needed. Long time ago when I ran FT cams I broke them in at 2000 rpm.

alswagg

Are you saying I have just been lucky???? No cam failures, no crank brg failures, no toasted engines. Now, I would have to say, we have not built and installed an old style flat tappet cammed engine for a very long time. If a pre Vortec engine comes in to be replaced, we build a Nice small block utilizing a ZZ4 rotating assy. As all know with this configuration roller lifters are used. Again, no special cam breakin. Again bullet proof engines. I guess I look at how manufacturing would build and prep. I just do not see GM running every motor for a special cam break in of 30 minutes at a constant rpm. The time restraints would dictate this alone. Al

jb78L-82

Not surprised! Any issues with your procedure and how long did you run 2,000 RPM? I would not be surprised if folks run 10-15 minutes, change the oil, and the cam lives a happy live. Trying to get a handle on this issue since I was never very comfortable with the logic and science behind 3,000 RPM for 30 minutes. A mechanic buddy of mine who has built MANY SBC's keeps telling me that he NEVER runs his cam changes for anywhere near what the manufacturers are recommending, so I am confused!

alswagg

http://forums.corvetteforum.com/c3-g...in-1970-a.html

This has already been discussed, but it is a great topic. I did not know GM ran the engines on Natural gas or propain on the assy line, Good idea due to lower emissions. Al

johnmb

Why would you take the chance?

cv67

Didnt hear that either but how to verify so it doesnt become a net rumor?

yellow 72

Set the idle to no less than 1500 and go do what you want with it....no need to sit in one place

MotorHead

They also have dyno rooms, I can assure you the first revolutions of the motor aren't from the guy who been there the longest and gets to drive them off the assembly line. They are already broken in. Knowadays who knows if they fire them at any point before the end of the line but it is not really needed unless checking for leaks or just making sure the engine is going to be OK. For all we know they could dyno test every motor and then send it over to the assembly line.

For us home garage guy start the motor, immediately set the timing as close as you can get. Use the idle screw and change the rpms every few minutes from 2 - 3000 RPM's