Engine break in advice

[Mtn_Man]

Well, about to pull the trigger on my freshly rebuilt 4.0 pushrod. The cam is the original. Checked oil and coolant several times. It has sat a few days with all the fluids in it and no leaks. I finished the sending unit install yesterday and there's 5 gallons of new gas in the tank. Freshly charged battery. All electrical and vacuum lines connected and checked multiple times. I plan on starting it up, spool it up to about 1500 rpm's for a few minutes then going for a short drive with a lot of gentle cycle speed up/ slow downs. Change the oil and filter when I get back and then go get a real tag . Did I miss anything? Should I unplug the coil pack and use the starter for a bit to prime the oiling system? I used lots of assembly lube everywhere on assembly.

 

[btexpress]

Running it at high idle is a good idea for a few minutes, then drive it like you intend to all the time, no need to baby it. You can wait til about 500 miles to chnage the oil and filter if you want, you'll catch more of the grit or anything else that might be left behind.

 

[jtison]

Congratulations

If you're reusing the old cam, the break-in period is a lot shorter and easier. You don't have to do anything special for rings any more, unless you used the cheapest possible cast iron rings (nobody uses those any more, I hope).

I also echo the "change the oil (and filter) after 500 miles" advice ... the chrome moly assembly lube used for certain parts (like cams) just might gum that filter up. Unless you built it yourself, change oil and filter.

Did you rebuild it yourself? If so, am interested in your experience ... am thinking of doing at least a valve job, and once those heads come off, might as well do bottom end, too.

I'm jealous

 

[little x]

Most wear occurs during the 1st 25 miles. You should change the oil & filter after the first trip (why let all those metal flakes ride around in there for the first 500 miles). And then change it again after 500.

Don't let it idol too long at first. And be sure to do several pulls from different RPM's to different RPM's while driving it.

 

[fobrnno]

here is some reading on engine break ins
http://www.mototuneusa.com./break_in_secrets.htm