i am putting a 50 into my 82 el camino, the 350 has 0 miles, how many miles will it take to break it in? in other words, when can i start blowin smoke?

I like to put 1,000 miles on my engines before I really get on 'em. For the first 500 miles I would keep it under 2,500-3,000rpm's. For the second 500 miles I would keep it under 4,000rpm's. And during the first 1,000miles I would not go beyond 1/2-throttle. Also, if a new cam is to be used, this should be broken in by holding the throttle at 2,000-2,500rpm's for 20-30 minutes. After the cam is broken in, change the oil and filter. After 500 miles change the oil and filter again. And it will be your choice to change the oil and filter again after 1,000miles. After that, the regular 3,000 mile intervals should be just fine. This is what I've done in all my engines and have had no problems.

Charles

A recommendation from the shop that built my engine was to take the engine gradually up to 5000 rpms & then let off & let the drive train slow you down. They said to do this a couple of times in first & second gear. It is supposed to help seat the rings. I don't know if this is true but it is what I did. I've since driven it like a rental with absolutely no problems. Jon

Years ago when I lived in North Carolina, a friend that had a garage and built racing engines helped me build a 60 over 283 with 10.5 to 1 pistons bored very loose. Break in went as follows: start engine, let idle until warmed up to operating temp, pull onto road, hold in first or second gear, stomp on it to almost redline on tach, let off throttle until almost down to idle, repeat this cycle 9 more times, pull into drive way, let idle until cooled down, change oil, it is now broke in, drive it as you plan to from now on, rings are seated.
Never did smoke, ran fine.
Had a 30/30 Duntov cam, 650 Holley double pumper with secondary jets bored on a drill press to .101, redlined at 6500rpm.
I was scared to do it this way but it worked fine.

Uhhhhh what kind of cam, roller or flat tappet, and stock lift or bigger , and how much seat pressure when valves are closed? All this makes a difference on break-in. If you are stock then run the engine through 5 heat cycles (hot to cold) hit the road and run up and down the rpm scale (1000-4000) for 20 minutes. Change oil and cut the filter apart and check for metal. The only thing to try and avoid for the first 1000 miles is lots of idling time. Good luck and enjoy.
George

Back when engine bearings wern't precision, rings were less than total seal and valve guides were barely adequate a careful breakin period was essential but nowadays it ain't necessary. Most important is the first 20-30 minutes of engine operation if you have a flat tappet cam. Do not ever let the engine idle bring it up immediately to 2000 rpm. I hate to disagree with Mama Mayhem but using his friends method will probably result in a flat cam lobe or two, or three. After the first 20-30 minutes of operation change the oil and filter because the cam lube that you used to assemble the engine will plug up the filter real fast. After that drive the car carefully for a few days listening for unusual noises, looking for leaks, etc. If everything is OK go out and smokeum.