ok so my 302 is almost ready... getting my heads ported today and then im ready to drop it in my 69 coupe.... but i have a question... so i had the engine bored over 40... and im going to be running a weiand 174 roots style blower on it... i have one friend telling me to break in the rebuilt engine first then add the blower later and i have another friend telling me to drop it all in at once and break the motor in with the blower.... so who is right... do i break it in with or with out the blower and for how many miles should i break it in before really working the engine

 

I have always heard, and always practiced "breaking it in like you drive it",,,, so for me that would include breaking it in with the blower, and driving the wheels off of the car.... if this is how I was going to drive it....

The only exception to my rule, is to not run the engine at one RPM for an extended period of time.

 

i agree with JMD i have always been taught to break it in how you will normally drive it. So after i rebuilt my motor with all of the goodies me and my dad went out front of my uncles shop and did a nice burnout to get things started off right

 

Welcome to 'the graveyard of the advocates of broke-in wrong motors'.
When you are ready -
-Fire it up and look for leaks immediately.
-If you got any, oil or water (live with the exhaust type of a while), shut it down immediately. That goes for 'bad' noises and viabrations too, engineinternal especially.
- Fix the leak and noise problems.
- If none or they're all fixed, fire it up and keep the engine running for 15 to 20 minutes at 1500 to 2000 rpm. Watch the thermostat. You can drive it but keep the rpms down.
- When done, take another valium.
Jim

 

yeah +1 for running at 1500-2000 for 15-20 minutes to let that new cam break in (and from i have been hearing about modern oils you need to use shell rotella)

i would break it in with the blower, but dont beat the crap out of it until the rings get a chance to seat. i dont care what anyone says, driving a new motor like you would normally drive it is not a good idea (if your idea or normally driving it is beating the crap outta it.... which is normal for me). do the typical oil change at 100 or so, 500 or so, 1000 or so, then every 3000. once your up to the 3000 mark i'd drive it like you stole it

...of course this is just my opinion and you know what they say about opinions

 

Opinions are like butt holes, everyone has one and they always stink...hehe

J/k good advise +1

 

you have a blower...
i want one...

 

+1 on running at 1,500-2,000 for 20-30min with a flat tappet cam, and +1 for Rotella as well. If it's a flat tappet cam, you MUST do these things or you run the risk of having a cam that eats itself in a few hundred miles. If it's a roller than this ain't an issue. As far as breaking it in with the blower, yeah, might as well. What you should do for break in though, after you fire it and check for leaks etc and it's good, and you run it at the rpm you need(for a flat tappet cam) LET IT WARM UP ALL THE WAY!!! then go drive it(consider changing the filter at this point, or just after you first drive it, since all the assembly lube and trash that comes out will RAPIDLY clog a filter and kick the filter bypass open and dump all that crap into your engine. That's the #1 cause of new engine failures these days). Break the engine in on a good quality mineral oil, like a straight 30wt or something. Go drive it, but not like an old lady. Don't run it ***** to the wall, but go out and drive it and give it WOT for a little bit in like 2nd or 3rd gear(again, don't tach it out) and then keep it in gear and decel in gear. Do this several times over a several mile distance. You MUST go to WOT if you want the rings to seat properly, the combustion pressure is what pushes the rings against the cylinder wall and makes them seal, and you need this force to cause the rings to wear on the cross-hatch and properly seat. Modern rings use a much finer cross hatch than back in the day, so the hatch wears off faster and if you don't go WOT breaking it in, the hatch will be gone before the rings completely seat. Again, don't drive it all out, but stomp on it for a few seconds, let off and coast back down, stomp on it again, coast back downetc etc. Make sure your oil pressure and temp etc stay good as well. Then, go change the oil and filter(again if you changed it once already and want to again). Changing the oil/filter early is vital