How long should I "break in" Fiona's new engine? It was a complete rebuild including bored cylinders and all-new pistons, new crank shaft, and totally rebuilt top-end. I also had them toss in a split-pin diff while they were inside. Paul recommended running Valvoline ZR1 racing oil in it for the break-in (and perhaps longer), as it's a petroleum-based oil, plus it contains the ablatives (ZDP?) that modern oils don't.
Mobil1 extended life (15,000 mile, gold bottle cap)is also a good high zinc oil that many folks with classic motors use...older motors, especially ones with flat tappets need the zinc to prevent gauling.... I would NOT use a newer formula oil, since most have been reformulated to be very low in zinc to extended the life of catylic converters.... For break in...talk to your builder...I suspect since it is an older motor desgin, built with (likely ) older tooling, an "old school" breakin might be best.... Some newer motors with very tight tolerances are OK with little or no break in....but a old school mini motor I suspect has much more "leway"...
Paul has rebuilt amd run several engines and speaks well of the ZR1 racing stuff. mainly because of the added zinc as noted. I was wondering more about HOW LONG I should keep it in there before changing. I also assume I should not really rev it while in break-in mode, correct? Anything else? What about highway driving?
Run the break in oil for 1,000 miles, then change it and the filter. I'm running Brad Penn 10W40 for the same reasons. The cam in my engine was supposed to be new 5K ago, but several of the lobes were completely worn out -my engine machinist said it was due to running modern oil with no ZDP. I've also heard good things about the Valvoline oil. As for how you drive it, stay away from redline if you can for the first 500 or so, and don't spend hours grinding away at one speed on the highway, other wise just let her rip. Have fun with it, that's why you built it, right?
I've been building engines of all stripes for about 45 years now, but I'll be the first to concede that everyone has their own preferred method of break-in. I'm of the opinion that there is no right or wrong way, save you don't want to run it full throttle (for long) or at steady speeds for long periods of time - which is difficult to do anyway given how crowded our roads are these days. Other than that, just drive it....don't lug it or overheat it and other than that don't worry about it! :biggrin5: The engine I built for Buzz is coming up on 1000 miles now and it's starting to loosen up a bit, the fuel mileage has increased significantly and it seems to run easier on the highway now. Once you get about 1000 miles you'll want to re-torque the head, re-adjust the valve clearances and change the oil. At that time you also need to double check the points and timing and you might need to fine tune the carbs a little bit. After that you shouldn't need to mess with it for many, many miles.
No points on my car (electronic ignition) but all the rest sounds like what I expected. Timing is currently set to 15 degrees of advance (huh?), but I'll adjust that in the Spring for sure down to 8 degrees or so. Thanks for the details - they really help! PS - Got my registration taken care of on my way to work this morning so I'm all ready to go once the weather breaks - it's supposed to stop raining this afternoon, then be sunny and warm(ish) for the rest of the week... Yaaay!!