I know you need to keep the throttle at 2,000 RPM for about 20 minutes or so, but my stupid question is, how do you keep the RPMs up there? I.e. how do you lock the throttle...or do you just screw the idle screw in a lot?

I use the idle screw. On my car ,IIRC, about 2-3 turns, maybe less, does it.

I've always had a buddy with me to help for a couple of reasons- to help make sure timing is good (glowing headers are a clue that it isn't right) & to set high idle from under the hood while I watch the tach to make sure RPMs are right. He can also watch for fluid leaks while I keep an eye on engine temp and oil pressure. I figure 2 pairs of eyes are better than 1.

Thanks guys. Was hoping it was as simple as the idle screw. Didn't want to have to sit a brick on the gas pedal or anything, lol.

Big Block,
Glowing headers would mean what, retarded?? Had that on my TA at start up with new cam.

soccerguy, go USC !!!!

Hi-po,
Yes, glowing headers typically indicate retarded timing. I've had this happen a couple of times myself. It gets your attention doesn't it? :eek:

It's also a good idea to vary the RPM's a little during break-in, a little higher once in awhile, little lower is OK....I broke in my last engine on a stand at the end of this past summer, borrowed it from a friend...I'll tell you what, Im either building one or buying one for next season, that was a great way to do it. graemlins/thumbsup.gif

Big Block, it was the most beautiful red /orange you ever saw smile.gif

DO NOT JUST SET THE IDLE SCREW & WALK AWAY... The rpm's need to vary during break in to insure that the oil gets slung all over the cam... Also, have the garden hose handy, if it starts to run hot, you can spray the rad, & cool it down..

As always, just my .02..
Scott

Originally posted by ssal396:
DO NOT JUST SET THE IDLE SCREW & WALK AWAY... The rpm's need to vary during break in to insure that the oil gets slung all over the cam... Also, have the garden hose handy, if it starts to run hot, you can spray the rad, & cool it down..

As always, just my .02..
Scott Good point. Hang in with it. And do vary the rpm some. Up to 2500 for a few minutes every few minutes. I use a hand held tach for monitoring engine speed. Fans in front of the radiator help keep temps in line. You can let the engine temp rise to about 220º but shut down if it goes over that. Time is cumulative so if you have to shut down after 10 minutes, you have 10 minutes of break in time left.

Just a few notes - maybe it will help someone. I think one of the major problems with cam break in is lifter bores that are tight or for some reason won't let the lifter rotate. We just ran into this on a neighbors car and rounded off a number of lobes on break in with his comp hyd cam. Took it apart and found that about half of the lifter bores were pretty rough. He honed them out a little and we tried again - no problems this time.

Also we used some diesel oil for break in the second time - Mobil Delvac 20-40w. Not sure if that helped or not but we thought it might help.

Ditto the water hose too!!

pdq67