For the love of god, not another break-in thread!

[Focker]

Don't worry, I'm not asking about break-in oil!!

I'm doing a complete rebuild on my 79 911. I have completely rebuilt the engine and pretty much everything else on the car.

Here in Vancouver we are in the rainy cold season, but I would like to at least do the initial cam break-in to make sure the new fuel system, oil cooler, ignition system, throttle linkage etc. etc. is all running right before totally buttoning up the interior etc.

Well, that's kind of a half truth. I also really want to fire up the engine to see if an accountant in his garage can successfully build a 3.2 short stroke motor.

I don't know when I would be able to drive the car to properly seal the rings and really run in the motor. Is there any risk to doing the 20 minute break-in for the cams then possibly have to wait a few months before driving it to start sealing the rings?

I might be over thinking things here, but I've put a ton of work into this and I'm nervous about f*cking up, but also want to find out if I f*cked up or not.

Thanks!

Ryan

[winders]

https://youtu.be/5Ruk6GLJgbA

[Focker]

Originally Posted by winders

https://youtu.be/5Ruk6GLJgbA

I know what I am watching tonight!

[stownsen914]

Worth keeping in mind - break in oil doesn't have the detergents and other additives/preservatives that normal engine oil does, and as such is intended more for short term use. Might be worth asking whether running the engine on break in oil and then letting it sit is OK for bearings.

[Focker]

I've decided I'm going to run the cams in at home then have the car trailered to a dyno to have the full break-in done to get the rings seated etc.

Jeff Alton/Turn 3 isn't far from me, so I'll ping him to see who he uses to dyno the car.

[winders]

Originally Posted by Focker

I've decided I'm going to run the cams in at home then have the car trailered to a dyno to have the full break-in done to get the rings seated etc.

Jeff Alton/Turn 3 isn't far from me, so I'll ping him to see who he uses to dyno the car.

You don't need to "run in" the cams. The only thing you need to do is get the rings run in. That's it. You can do that in about an hour on the dyno. The worst thing you can do is start the engine and run it with no load for 20 minutes to "run in" the cams.....

[dannobee]

Yeah, actually you DO need to "run in" the cams. Get everything ready to fire. Oil, fuel, battery fully charged, ignition timing set, etc. Set the idle screw(s) up a couple of turns. Then light it off and let it run for 20 minutes with the idle speed not dropping below 2000 rpm. This will properly break in the cams.

[winders]

That is the worst thing you can do to a rebuilt Porsche 911 engine is to let it idle at ~2000 RPMs for 20 minutes....jeez. This is not a pushrod engine...

[dannobee]

Stop right there.

Go educate yourself.

These aren't roller cam engines. Cam break-in procedures MUST be followed otherwise you run the risk of damaged cams and rocker arms.

[winders]

I have. I suppose you are going to tell me the engine needs some heat cycles and the bearings need to run in too....

The cams and rockers in these engines are bathed in oil. Start the engine at idle it at around 2000 RPM, verify it is making good oil pressure, and warm it up for a few minutes. While it is warming up, make sure it is not leaking oil from anywhere. One you are sure it is not leaking oil, shut it off and take it to the dyno for intitial tune, break-in, and then final tune. The break-in procedure outlined in the video I linked is great.

[Focker]

Originally Posted by winders

You don't need to "run in" the cams. The only thing you need to do is get the rings run in. That's it. You can do that in about an hour on the dyno. The worst thing you can do is start the engine and run it with no load for 20 minutes to "run in" the cams.....

They are new cams. Yes, they do need to be broken in.

[Focker]

Originally Posted by winders

I have. I suppose you are going to tell me the engine needs some heat cycles and the bearings need to run in too....

The cams and rockers in these engines are bathed in oil. Start the engine at idle it at around 2000 RPM, verify it is making good oil pressure, and warm it up for a few minutes. While it is warming up, make sure it is not leaking oil from anywhere. One you are sure it is not leaking oil, shut it off and take it to the dyno for intitial tune, break-in, and then final tune. The break-in procedure outlined in the video I linked is great.

Bro...it's a flat tappet cam that must be broken in. They even say so in the video.

Using your method would toast a set of cams and rockers. Jesus.

[winders]

Yeah, except as is outlined in the video, this is really an issue with flat tappet pushrod engines that have tappets that rotate. The air-cooled 911 is not really a flat tappet design as there are no flat tappets. There are rockers and the surface of the rocker that follows the cam clearly does not rotate.

The key here is assembling the engine with enough lube to protect the rocker/cam interface at first startup until oil pressure has built up and oil is present. The break-in oil needs to be high in ZDDP.

If you start the engine and run it at around 2000 RPM and let it warm up while inspecting for leaks...which shouldn't take more than 5 minutes....and then go through a reasonable process of seating the rings, the cams and rockers will break in perfectly as well.

Unlike a pushrod engine, even at idle the cams and rockers should be getting an abundance of oil on them. Unlike a pushrod engine, you don't have flat tappets that need to rotate and match up to the cam at all degrees of rotation.

I am not suggesting you should just start the engine up and start running the engine from idle to redline, under load or not, without regard for the cams and rockers.

However, with my current race engine, I've broken a rocker on multiple occasions and replaced it between races. I then proceeded to race hard (8000 RPMs) right away. I had to pull the heads on this engine before the last event and we inspected the rockers and the cams. You could not tell which cam lobes had run with replacement rockers and you could not tell which rockers were not originally in the engine at break-in.

[Neil Harvey]

Hmmm'

These forums are for the sharing of knowledge and experience. Some of us have years in this business who hopefully have a little more knowledge and experience than others.

In all the years I have been doing this sort of work, even years ago in my time in F1, there was never a " its the only way" to do anything. But there are many thing I have learned over the years that always give a great result without any chance of hurting something. I have never had the experience of doing something with care and ended up with damage. However, we all can tell a story where we decided to throw caution to the wind and it ended badly.

Are these engines worth the time to give them that extra attention and care? I think so.

Remember, "nothing will humble a man more than an engine or an angry wife.

[Richey]

I agree with Winders , do not let the engine run at 2000 rpm for 20 minutes with no load , the rings will nor break-in properly . After the engine is warm a load must be applied . The rings must be pressed against the cylinder walls when the honing is still present and not worn away .

[dannobee]

It doesn't matter what you two think. Just because you got away with it once or twice means you just got lucky.

Focker specifically asked about cam break-in procedures.

Go ask your cam grinder what he wants. He'll tell you what we both repeated; 2000rpm for 20 minutes.

Read step 7 on any Porsche 911 camshaft on the web cams website's installation information and get back to us.

Since we're on Wayne's forum, see what he says in his rebuilding book; 2000rpm for 20 minutes.

Any modern set of rings are "seated" by the time the starter motor finishes the initial start-up and certainly within a pull or two on the dyno (or a spirited romp down the street).

https://www.enginebuildermag.com/2018/05/how-to-break-in-your-piston-rings-the-right-way/

Some of us here have a LOT more than just a few engine builds under our belt. Maybe you should listen.

[Focker]

Thanks all. Feeling pretty good about cam break in at home, then complete breakin on dyno.

[winders]

Originally Posted by dannobee

Read step 7 on any Porsche 911 camshaft on the web cams website's installation information and get back to us.

Here is what Web Cam's step 7 says:

"For proper break-in, after installation of a new camshaft, do not allow your engine to idle below 2000 RPM for the first 15 minutes of use."

That is a lot different than saying you need to let the engine idle at over 2000 RPMs for 20 minutes. They just don't want the engine idling at less than 2000 RPMs for the first 20 minutes.

So, starting the engine, setting the idle at ~2000 RPM, checking for leaks, stopping the engine, breaking the rings in on a dyno (never letting the engine just idle at under 2000 RPM for the first 15 total minutes of run time), is exactly what I suggested doing.

The first step of the break in process on the dyno has the engine running at varying RPMs between 2000 and ~4000 RPMs with the throttle at no more than 30% for the first 15 minutes or so. So, if you take the initial startup and check for leaks all above 2000 RPMs and then do the first ring break-in session, you have the engine running at above 2000 RPM with no massive loads or high RPM runs for about 20 minutes. That sounds like exactly what Web Cam wants done.

After all, we "did not allow our engine to idle below 2000 RPM for the first 15 minutes of use".

This keeps the cams and rockers happy AND allows for proper ring break in.

[winders]

Oh, to back up my point:

https://forums.pelicanparts.com/10591282-post9.html

https://forums.pelicanparts.com/10591358-post10.html

[Richey]

Scott is understanding all the issues , whereas the camshaft people are concerned mainly with the camshafts .