Break in

I will be breaking in a newly rbuilt engine shortly. I wanted to get opinions on break in procedures. I think I will use a straite 30W non detergent oil for the break in. I've heard that for the initial 15 minutes to 30 minutes the RPM's should be up to break in the valve train/ cam shaft. The elevated RPM's reduce the loads the valve train sees. how about the rest of the break in? when should I change that initial oil load? I've also heard that one should set up the engine lean initialy this helps break in the rings and cylinders. This is a 2.7l RS spec. engine, I've also heard that for some reason that ring piston break in is not the easiest. Any comments?

Bruce

The break-in rpm's need to be above 1500 rpm, and below 4000 rpm, and constantly varying, and do not use wide-open throttle ANY at all! Are you planning to drive it in the car, after the first 15-20 minute period, or is this strictly a bench-test? It would probably be OK to do several heat cycles, or test drives over a two-day, 200 mile break-in, but after approximately one or two days you definitely want to change the oil, and filter. I'm not sure about the non-detergent oil business, I think that is an old wive's tale from the '40s and '50s, and I have always used the same type and brand of oil I was going to use in the engine. Valvoline Racing 15W-50, or straigfht SAE 30 wt. would be my choice. Whether you do the multiple heat/cool cycle bit over a two day period or not, check the valve clearances after you drain the oil for the first time and have let it cool down to room temperature. As far as breaking in the rings go, I think avoiding full throttle and keeping rpm's under 4000 are safeguards against any problems ... Nikasil cylinders do not really have any break-in problems! One precaution: you did pre-fill the injection pump with engine oil, right? The injection pump stays filled with oil after oil changes ... that is one reason for NOT starting with the non-detergent oil ... whatever oil you put in it for break-in will still be in the injection pump after you drain and change all of the other break-in oil!!!

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Warren Hall
1973 911S Targa

Warren thanks for the reply. Is the injection pump issue really that an issue? It seems that the pump may hold all of a pint of oil if that.This would quickly be absorbed into the main body of the oil system. It seems to Me that this would have minimal impact. The engine will be started in the car.

It's probably not a big issue ... but considering that it is the single, most-expensive conponent in the entire engine, I thought I should mention it.

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Warren Hall
1973 911S Targa

Am I correct in assuming that the oil in that pump does have a pretty hefty turn over rate? Oh yeah I also want to mention that i too have been seduced by the MOBIL 1 bug, I just read a few comments over the last two days. I was wondering who out there has used it and gone back due to bad experience and who has used it and stayed on it?

Bruce

The oil line from the oil line under the pressure sender (banjo fitting) is only 1-2 mm, and the overflow hose into the crankcase vent is large, on the order of 12 mm, but I don't really have a feel for how quickly, or if the pressure line does anything but keep the injection pump 'topped-up' ... I'm not so sure the non-detergent oil from break-in will leave the injection pump, except by very slow dilution and migration. You did not say whether the injection pump was pre-filled. If it was not pre-filled with a premium oil, I have to assume all of the initial filling will be with your break-in oil!

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Warren Hall
1973 911S Targa