[Michael]

Why is it that I hear so many people say to break in a new motor by driving easy for a break in and I hear others build a new mtor and immediately flog it on the dyno w/ no problems? What gives?

 

[Wes Colby]

Michael, I too have heard the same. It seems that more professional high performance engine builders (ie. shops that build only race and/or high-po street/strip motors) recommend NOT pussy footing around with a new rebuild, but rather to get into it immediately after initial cam break-in.

Nearly three years ago, when my 383 was assembled by a local circle track builder, I was surprised by his instructions as well. He basically told me to get my foot into it after the initial camshaft break-in and oil/filter change. I remember him being rather seriously dogmatic about not messing around with going easy on my new engine. I was cautious about really leaning on the engine and he sensed that from me. So, I obliged and ran that poor stroker really hard that weekend! I know to this day that the speed runs I put my engine through didn't hurt it one bit. You cannot tell at all if this motor is burning oil b/c the dipstick levels have never moved downward the slightest bit and the blow-by levels (with PCV disconnected) are barely detectable - I mean you have to really watch the unplugged valve cover grommet to see any smoke coming out.

The machine shop I used did charge my Master Card a hefty wollup. I had never used a shop like this before and was surprised at the high cost of good quality machine work. These guys have been doing this for over 20 years and looking back I have to think that the quality of the engine rebuild has had everything to do with the performance of this motor today. And maybe there IS a coorelation between break-in procedures and how and to what level an engine is built...not sure if this answers your question or not but it may be worth considering. Any professional engine builders out there?

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'70 Malibu - 383 'Fog Fed' Stroker! Houston, Texas Gold Member #39
Chevellz Alwayz!

 

[DZAUTO]

Mike,
I agree with Wes. On a new engine build (or a cam replacement), go by the book for cam run-in (about 20 min @ 2500-3000rpm) and after that, tune it, time it, change oil/filter and then the sky is the limit. Back it out the garage door and go terrify your mother-in-law.

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Tom Parsons

[This message has been edited by DZAUTO (edited 11-29-99).]

 

[dave silva]

My machine shop recommended the same treatment. Break in cam then go for it, also when I get a new race motor for the circle track, we break in the cam and then it is off to qualify or a fast session of hot laps. Our motors are just as powerful, and there is no noticable problems. The motor was faster and got faster throughout the rest of the year and is still strong for this next year.

 

[283v8]

OK, this is just MY theory, but for years I have thought about this.
First, running hard puts more pressure behind the rings and forces them harder against the cylinder wall. Also, with harder use, different forces occur at different times. In other words, really hittin' it causes the max force on the rods, pistons, cam, etc to happen at slightly different places times, and angles than babying it. This puts wear at slightly different locations on cyl. walls, the cam, the crank etc.
Think of "break in" rather as "final machining" of the parts and it makes sense to create wear patterns and wear locations where they will be run and stressed the most.
Once this admittedly slight "wear in" occurs, all the parts are precisely fit together as they will be run later.
Also, break in is hardly as important today as it was with the much more crude and less accurate machining practices of 30 years ago.
Sounds logical to me - whaddya think ?

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Gotta have a Chevy !In Durham N.C.
Why is there never enough time or money to do it right the first time, but ALWAYS enough to do it over?
Make it look the way you like it, forget what the other guys say!

 

[Quadzilla]

I just wanna hop in on this about the "crude machining" of 30 years ago. Modern machining processes have existed for most of this century, and to my knowlage have been rather exacting. I think it would be wise to draw a difference between what a race shop will build you and what a guy on an assembly line woking for peanuts and is 20 minutes late on leaving will build you.

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Francis Taracido Gold# 201
[email protected]
History shows again and again how nature points out the folly of man.
Oh No! You Know She's Got To Go!
Go Go Quadzilla! <oo=+=oo>
members.aol.com/sniper0666/page/index.html

 

[gUmBaLL68Malibu]

My engine will be done tommorow and they told me not to hammer on it to much becuase it was just line bored and they want the rings to seat correctly but they have never babbied a car b4 they just race em once there done. They said due to the line boring that i should baby it i trust them they know what they are doing so i was just wondering if the fresh boring made a difference.

 

[Gandalf80]

While the machining may not be the major factor in today's engines not being affected as much by breakin, I believe that the materials used to make the parts plays a larger role, like moly rings and pistons etc.

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Chris Dagenais
Saskatchewan
'71 Malibu with a home built 454!
member.xoom.com/Gandalf80/