How was break-in handled on our old 911s?

mca · 08-25-2008, 07:55 AM

Curiousity is getting the best of me ... I want to know how our 20+ year old cars were broken in when they were new.

Did the factory run them in before delivering to the dealerships? If not, were buyers given specific instructions?

I am currently breaking in a rebuilt 3.0. The process requires careful attention to RPMs, changing oil multiple times, etc.

I can't imagine that buyers back in the late 70s and 80s would have to run the car for 20 mins at 2k RPM ... change the oil ... drive the car 30-50 miles while varying the RPMs ... change oil again ... drive 500 miles ... change oil again and perform valve adjust ... drive another 500 miles (now at 1k total) ... change oil again, adjust valves, and torque head studs.

Anyone know?

vntgspd · 08-25-2008, 08:03 AM

MCA -

I asked this question to a very reputable shop that frequents this board and got the following response:

Well, generally, we run them pretty hard to get the rings to seat. Running up and down the rev range on the road (or dyno)helps this process. Run it up and down in 2nd and 3rd up to 5500 or so and back again several times. You don't want to just let it sit and free rev it, there should be a load on it. Change oil, retorque heads, and adjust valves at 1000 miles. Even at 500 for an MFI or carburated motor because they run so rich and can contaminate the oil with fuel very quickly. Many use this guys theory:

http://www.mototuneusa.com/break_in_secrets.htm

I followed their recommendations except that I followed the oil change recommendations in Wayne's book. My car runs exceptionally well and has noticeably more power than it did last time the motor was freshened.

mca · 08-25-2008, 08:23 AM

Yeah, I understand the process ... but I was wondering how the break-in was done when our cars were brand new.

Back in the 70s and 80s ... not how to break-in a rebuilt engine.

1982911SCTarga · 08-25-2008, 08:57 AM

I think (and there are others far more knowledgeable than me here) that the engines were assembled and then run first on a dyno in the engine-building shop. Following that, they went on the line with the transaxle to be joined with the chassis. After the car rolled off the line at Zuffenhausen, it was then taken on a 30-plus mile shakedown cruise during which the factory test-drivers made notes of pass/fail items and things to be corrected (you think the engine saw the redline repeatedly during that cruise?) before final delivery. I also think much of this is still the case with the modern Zuffenhausen-built 911 derivatives (is it the 997 now?).

Jack Olsen posted some really cool vintage videos that showed the factory test drivers taking 911s out for their shakedown in the early 1970s.

Brian

Jim727 · 08-25-2008, 09:07 AM

From my '71T owner's manual:

mca · 08-25-2008, 10:21 AM

Jim / Brian,

Excellent info. Sounds like the factory did the first run, a few test runs, and then packed em up.

Really cool to read that 71 manual. I was surprised to see that 1200 miles is the point at which you can let it all hang out.

Thanks for chiming it. Exactly what I was after.