I've searched here and at other sites for engine break-in procedures. I've done the cam break-in and the motor is now in the car with fresh 20-50 Brad Penn and a new oil filter. Valves have been checked. Fingers crossed.

From what I've gathered, most recommend warming up the engine and then doing a series of fairly hard accelerations under load followed by de-accelerations to help seat the rings, and in between, no sustained rpm driving. Some go as far as recommending you drive it like you stole it and others (Aircooled.net) say drive it easy for the first 100 miles.

I also tried to determine when best to change the oil. Do I need to change it at 100 miles and then again at 500 miles (and then every 3000 miles thereafter)?

sounds right!!

Uh, cowboy, he qouted 3 different break in options. Which one "sounds right"?

From what I've gathered, most recommend warming up the engine and then doing a series of fairly hard accelerations under load followed by de-accelerations to help seat the rings, and in between, no sustained rpm driving. Some go as far as recommending you drive it like you stole it and others (Aircooled.net)

those 2 above are the same and sounds right, old thoery was take it easy which is now debatable with the hard driving break in..

full load drive it like you stole it! to seat the rings..

i bought my 914 w/ 8,000 miles on a rebuild, the p.o. babied the car, actually buying it was like taking a child from his mother.

when I opened it up the cylinders walls showed that the rings nevr seated, I could still see the original honing crosshatch..

THAT IS WHY I LEAN TO THE DRIVE IT HARD FOR 20 MINUTES

I just looked at my 73 owner's manual, which said there is "... no special break in required for your 914 roadster ....", other than to generally keep it under 5000 rpm in most "normal" driving conditions. Moreover - I never had any such break-in required when I had the original 2.0 rebuilt in my 914, nor for the 2.1 waterboxer new longblock in our 88 Westy!

So I don't know where nor why anyone would reccomend such a over-the-top break-in as described above!!??

Joe, given the above, what you saw when you cracked open yours could've been due to a bad or incomplete rebuild, inferior parts, abuse (maybe the PO's rebuilder did the abusive break-in noted above), or from the DAPO babying it too much. It sounds more like the rings were perhaps too small for the rebuild's honing if it didn't seat after 8000 miles babied or not, rather than not thrashed into submission to seat them.

My long term 914 expert Hans did always say never to baby a 914 & that they were made to be driven hard - but not any sort of aggressive break in. If you doubt it, call Hans Imports & Huntington Beach & ask Hans (Sr.) or Carl - as they've rebuilt more Type IV's than almost anybody here, & Hans was trained on 914s at the factory in the early 70's & knows them inside & out! Cevan - it's long distance, but you could call them too (PM me for tel. or google them)!

The owners manual/service reccos gives the initial & every 3-6000 miles oil change IIRC, which I would follow if it's a stock US or Euro spec rebuild. If it's an upbuild (2056, 2270, etc.) then follow the engine builders' or kit maker's reccos.

Tom T
Orange CA
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Chris...
Drive from your house to Rt 2 and back a few times.
That road is perfect.
Dont be timid.
Rich

So close. Couldn't get the damn thing to fire. Pulled a hose off one of the carbs. Run the fuel pump. No fuel. Hmmmm. I figure it's gotta be between the pump and the carbs. Pinched fuel line under the tank?

So I pull up the passenger side of the tank and see that the line is pinched like you'd pinch a garden hose to stop the flow. Whew! I see that I installed the fuel outlets pointing the wrong way. I undo the pinch and drop the tank enough to get the fuel to the outlet and it fires right up. Yes!

Anyways, siphoned enough gas to be able to turn the outlet 180 degrees and put everything back together. Now it's 9pm. Tomorrow morning I hope to take it for a good romp.

Get underneath (after you put the tank back down) and use a small mirror and a light to look into the 3 inch hole that is right under the tank.

You need to check the hoses to make sure they dont kink when you sent the tank back down.
Dont feel bad,,,,guess how I know.
Rich

Well I actually drove it on a public road this morning before work.

I didn't go to WOT but it seemed to pull smoothly. I was going to drive about a 7-8 mile loop around my house but about 2 miles into it, it started to get boggy on acceleration so I pulled over to inspect things. One of the nuts holding the return spring and throttle stop has come loose and disappeared. I'm not sure this is the cause. I turned around and headed home. I made it back into the garage so I call it a successful 1st drive.

They don't call them shakedown cruises for nothin'!

First time I drove mine after the 2009 rebuild, I had my carb linkage start backing off. Came to a stop sign and had a 4000RPM idle. Yipe! Funny thing about nuts you forget to tighten.

15 minutes later I was readjusted and back on the road.

Zach

thank gawd we are not fixxing airplanes. that is a shake down flight I wont be on.

Lets go over a few things......

The cam manufacturers want you to keep a nice steady medium RPM load to break in the cam and lifters, the worst scenario for the rings (but they only care about their cam). Slow rotation has a tendency to "gall" new cam components.

New engines built these days are built to much tighter tolerance than the old days. You notice that they run 5-30w oil and still have good oil pressure.

You can't use your owners manual as a reference to break in for a "rebuilt" engine. You don't have the machinery that the factory did to machine, assemble or break in the engine. Your case is not as straight, the holes not as round, the crank not as straight etc etc....

Now for the important (in my opinion).....Rings. Get it wrong and have a smoker or lower compression.

Rings seal not by the pressure of the spring action of the rings but gas pressure BEHIND the ring. When the engine fires, gas pressure pushes downward on the ring, works behind the ring and the pressure forces the ring outwards to seal against the cylinder. Ever notice the wear on the top of the cylinder is always worse than the bottom? That's because the top has the most gas pressure behind the ring.

When an engine is new and the cylinders freshly honed with new rings there is only a short period of time to "seat" the rings. The cylinders quickly "glaze" in a very short time making ring seating difficult. The key is to wear the high spots off and make a good seal to the cylinder wall as quickly as possible. I have torn down many a race motor and I can assure you the cylinders glaze faster than you can imagine.

For the rings to seat they need gas pressure and that means stepping on the throttle. That action generates localized heat though. The key is load and then unload to cool.....repeat, repeat, repeat. Let it cool down and start over. The worst thing you can do is to putz around town with tender loving care never stepping down on the throttle and never exerting pressure on the rings. Yeah everything will break in real nice except the rings!

Sitting in your garage running for an hour is the WORST thing for a new engine. Get it going, get it on the road and get on and off the throttle avoiding high RPMs. Accelerate hard then get off the gas for a bit....It won't hurt that cam you are so worried about.

Please see my comments in This Thread

I hope this long-winded response will help those understand what's going on when their engine is new