Check this out, this is how I broke in my klx650 and there have been no problems and the motor hauls...

http://www.mototuneusa.com/break_in_secrets.htm

 

That is the one I was referring to as well but could not find it.

 

Nobody bothered to ask the important question here:

Is it a roller cam, or is it a flat-tappet cam?

I noticed you said it's a 71 block but that doesn't give me much other information.

If it is a flat-tappet cam, then you need to properly break that cam in so you don't wipe the lobes off of it. If it is possible, I would try to pre-lube the engine through the distributor hole prior to firing it up. You're going to want to hit the timing as close to perfect as you can when you stab it. It would be beneficial to have a 2nd person to keep the car NOT idling if you have to make any timing adjustments once the car fires up.

Assuming that it fires up, and the timing is good, you want to do a ~20 minute camshaft break-in. This is nothing more than VARYING the RPM between 1500-2500 RPM (some say 2000-3000, 1500-3000, everyone is different, you just don't want to IDLE, and you don't want to go overboard either). If the engine is idling, you're not getting enough oil flowing over everything to keep the cam & lifters lubricated. This process will basically let the lifters and camshaft mate to each other.

During this time you're going to want to check for any leaks or other issues too.

Once the time is up, cut the engine, drain the oil, change the filter, and fill it back up. You still don't want to idle the engine, because you need to SEAT the rings. Need to take advantage of the SHARP cylinder cross-hatch BEFORE the rings round them over. I would do like stated on the Mototune link above and do the 1/2, 3/4, and full-throttle pulls. You need to get PRESSURE in there and force them rings against the bore. I'm a little ****, so I would probably change the oil again soon after this is done.



IF it is a roller cam, skip the cam break-in step, and just do the 2nd part. Before you head out, get it up to operating temps, make sure everything is kosher, no leaks, timing is good, all that. I usually change the oil here just to get rid of all the assembly lube and all the other loose metal that may be in there. $10 worth of oil is nothing compared to the cost of the engine. Then take it out on the road and do "part 2".

JMO.

 

Great post, Dave-- as usual!

I'll only add that the engine needs a LOAD on it to properly break it in. The Mototune way is the best way, imo. Ditto on the roller vs. flat cam break in.

I'd personally try to combine the cam break-in and the engine break-in routines. You want to break-in the rings as early as possible, and IMO the 20min of runtime associated with breaking in a cam is too long-- the optimal break-in window will have passed.

So, here's what I'd for a flat tappet cam:
-- Prelube with the drill as Dave mentioned. (oil pump adapters are easy to find from Jeg's/Summit, etc).
-- Set the static timing at something fairly safe and universal: say 10º or so.
-- WITH THE ENGINE IN THE CAR/TRUCK, start it up and immediately go to 2500rpm until the engine comes up to operating temperature. This will probably take 10-15 minutes, as installed in the car.
-- When the engine is finally warmed up, begin the first break-in round, reaching max rpm at 50% throttle or so. Ideally, you'd have the car in low gear and be able to hit the pedal until max rpm, then let off and coast down to 2500rpm, then repeat this cycle for 5 minutes or so
-- Shut the engine off and let it cool a bit (10-15min)
-- Start it up, repeat on the "nail it, coast it" routine only use 75% throttle this time. Do this for at least 5 minutes.
-- Let the engine cool for 10-15 min
-- Fire it up again and do the "nail it, coast it" routine using WOT until the engine is good and hot (at least 5-10min).
-- Shut the engine off-- drain the hot oil out-- every last drop.
-- Refill the engine with your oil of choice.

Done!

 

Thanks Justin. I've heard of people doing a few different things in relation to time with the cam break-in, as well as RPM...I figured I'd take an average and hope for the best, no problems yet.

You nailed it with the LOAD for a proper break-in though. It KILLS KILLS KILLS me when I see these guys go out and spend $6000-$8000 on some badbum race engine, and get it installed, finally get it to fire it up, and then just let it sit there and idle, and listen to how badbum it sounds, blipping the throttle now and then. KILLS me.

Like that mototune article says, if you don't have a load, the rings are just "along for the ride". Get them suckers against the wall!

 

I know a mechanic who bought a 78-79 Chevy 3500 full time 4x4 with a 400 and auto new. He drove it like a grandma from dealer to home, then the next morning to work. Did about 30 miles he said. His boss borrowed the truck (NEVER let the happen!) and goes "John! That is the best running truck ever! It did 125 mph!" He still has it and has never done any internal work to it, still runs great! No smoke, and he says still does 130 mph. Now it has 150,000+ miles on it. And he used it for farming after that hauling grain wagons.

 

I've always gone with the break the cam in at 2500RPM for 30 minutes then beat the snot ot of it. Oil changes after the cam break-in, 500 miles, and then regular intervals after that.

Might be a good idea to cut the filters apart too so that you can track how much metal is coming out.

 

Sorry, forgot to say it's a flat-tappet cam. I assumed people would assume it was. Got it fired up yesterday, but only did the 20 min cam break in because it blew out the cheap gasket the headers came with on #3. I did the pre-lube, and had the builder come and set timing and double check everything for me. Everything went good besides the exhaust leak. I will use the method Dave88LX and HOHN descibed, as that's the same one the builder recommended. I have some good gaskets coming tomorrow, so hopefully I can do the driving break in tomorrow. Thanks for the info guys.

 

Breaking in a flat tappet cam is such a PITB that I'd install the Schubeck lifters just to not have to deal with it and have a cam last forever, too

Ceramic composite rocks for tappet faces!