Let the debate begin.
What's the best way? Slow and easy for the first 500 miles or 2000 rpms for 20mins right off.

Robert

slow and easy... just like anything else you break-in, like a brand new clutch or a rebuilt transmission plus any minor mis-adjustments will probally give you a big problem if you start stressing that motor right off the bat, but im sure the lifters might loosen up after a while

Suggest you read this:

Break-in Secrets

A deceased friend of mine (who worked for me for a while) and was a mechanic on the side most of his life - swore by the aggressive break-in style. He showed me the technique on my 4X4 which we rebuilt together. 30K miles later - no problems whatsoever.

You DO know about immediately after staring the motor running it between 2000 and 2500 rpm for 20 minutes to break in the cam, right? (the high rpm ensures a good, continuous oil splash on the cam)

That article is about breaking in a new or freshly rebuilt engine to seal the rings correctly. If you are just replacing the cam and lifters you should follow the breakin procedure that comes with the cam. Mine was to apply lots of the cam lube that came in the kit to both the lifters and cam lobes. You must get the engine setup so it will start right away. I poured a couple ounces of gas right down into the carb and it fired right up. Then keep the RPMs up over 2000 and blip it up to 2500-3000 or so every so often. Watch the oil pressure - it should stay at 60 psi. Keep this up for 20 minutes. Change the oil and filter and you should be good to go. Of course I haven't driven mine more than 10 miles since then, but I'm crossing my fingers

I know a very reputable engine builder who after he does the initial 20 min. break in.
He take the car straight to the track.

I believe in the 20 min.@2000RPM method is the way to go,I have rebuilt many engines including changing only cam and lifters and I have never had a problem with them coming back.And besides if you think about it the whole idea of the "500 mile break-in" is BS,I know alot of you have seen this done before on shows on Speed Channel and I have seen it at engine shops,they take a freshly built engine and run the heck out them on the dyno,that`s their"500 mile break-in",and the engines usually last without problems.

Anywhere between 1500-2000 RPM for approximatly 20 minutes should be fine. Shut off engine & let cool & change oil & filter. This will get all metal particles out of engine from the break-in run. Drive easy for awhile to let engine continue to break-in, at least a few thousand miles, IMO. After that, let 'er rip!!

Steve

just brining this topic to the top as i'm nearing this point with my engine.

Don't forget the break-in lube. EOS or ZDDP or some sort of break-in additive.
Also last one I broke in I removed the inner valve springs for the initial break-in period to ease things a bit. Kind of a PITA because you have to break it down and reinstall them and re-set the rockers again but it's easier than replacing the cam.

<--cringe at the thought!

i'm useing brad penn breakin oil,do i need to add other additives as well?

I used the 20 min 2000 RPM method then easy for about 1000 miles. I did not know about or use ZDDP or break in oil, but used a good quality oil. Everything is running greeaat at about 4000 miles now. I have ZDDP in now tho!

the breakin oil is just for the first 20 min initial startup then it is drained and replaced with your regular oil(i'm using brad penn oil).filter is changed also after the first 20 min.would there be any benifit to do the first 20 min breakin twice.

Don't think so. They say 20 mins is long enough to mate the lifters and cam lobes to each others shape and finish.

I just hope the molecules in your cams, hold hands much better than mine did!

gotta think positve Joe!

Tough to do when you been through what I have with cams! LOL