Yes, but he never said drive it, when he was talking about flat tapit cams, which was my point. Sorry my choice of words.

What do you you think is required when you need to vary load and RPM? You can’t do that in the garage. You can do that on an engine dyno, a chassis dyno, or by driving it.

My takeaway here is this.

Pre-oil the motor.

Start and maintain at least 2000 rpm.

When the oil reaches 140 drive normally, (varying engine speed), without heavily loading the motor, and maintaining an RPM range of 2000 to 5000.

After 20 minutes, change the oil and adjust the valves.

Drive normally there after.

Some great information here. Really appreciate all the sharing.

Thanks for all the info guys!

My situation is a bit different. I've had my cams and rockers ground but haven't touched the cylinders or rings. In this case do I only care about getting up to ~2500rpm and holding for the cams as rings won't be an issue?

Is a valve adjustment really necessary at the end of that first twenty minutes? My thought had been to only change the oil after twenty minutes, and check rockers and valves at 1,000 miles.

BTW, I forgot to mention that I have modified cam oil restrictors. I drilled them out to 4.5 mm however, as mentioned here http://forums.pelicanparts.com/911-engine-rebuilding-forum/1122559-camshaft-oil-pressure-restrictors.html and in an older thread.

Perhaps during cam break-in no restrictor?

John Dougherty liked this idea...
 

Hi Gordon,
I posed this same question to John Dougherty, (since we both have his cams), and he liked the idea of running the big stock restrictor for cam break in, but did not suggest a mileage change over point or size to go to.
Looking forward to further input/clarification for the 2.8 hot rod build.
chris

This video seems to suggest breaking in cam first then going for a drive to break in rings....hmm.

https://youtu.be/MhA_nVRhYew?si=gFfFw8MaoMy638l6

Not really. They are talking about braking in the camshaft when you don't have access to a dyno. If you have access to a dyno, it is easy to keep the revs up AND to do the normal ring seating procedures.

Man this topic confuses me.

I guess I had always figured the 20 minutes at 2000 rpm with no load was to break in the cam without any load on the rings - preserving them in their "rough" state until the cams were broken in.

Then, get rid of the cam detritus via an oil change and then get on with breaking in the relatively "unmarred, untouched" rings via a drive with varying load and rpm.

I don't know what I will do with my 3.4 but by default I am following Wayne's book...

D.

Well they say break in the cam 20mins at 2500-3000 rpm in the driveway then go for a drive to break in the rings.

Yeah, I guess I was assuming this thread was mostly people who were going to be breaking in their engines in car not on a dyno.

You can always get rings to seat later (unless something is really amiss), you can't always get your cam lobes back.

Cam break-in, IMO is more important.

Does delaying the ring break-in procedure (to do the cam break in procedure first) compromise the end result?

I know that I am more concerned with seating the rings than I am with bedding in the cams and rockers...mostly because I keep the engine above 2000 RPMs for at least 20 minutes during the initial engine break in process...

I am concerned with that as well but find it difficult to believe i could keep the rpms above 2000 while navigating traffic. Good to hear seating rings can happen after initial cam break in.

C.