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Re: regarding engine rebuilds

Subject: Re: regarding engine rebuilds
From: "John M. Trindle" <>
Date: Thu, 23 Feb 1995 10:22:08 +0000
On Thu, 23 Feb 1995, Will Zehring wrote:

> #3:  keeping on the theme of engine rebuilds: I have high hopes of getting 
> Old Whitesides ('63B) back on the road in March.  Yipeeee  :-)!  The car 
> only has about 200 miles on its "new" engine.  There is a faint chance that 
> I'd like to take the car to North Carolina in April or May (from Detroit).  
> Any thoughts on the suitability of extended highway travel on a reletively 
> fresh engine?  I'm hoping that by departure time I'll have put another 300 
> or so miles on it, mostly commutes and around town stuff.  Of course, there 

I would think by this point you would have broken it in (500 miles?).  
The combination of commutes (I assume short stretches at highway speeds) 
and stop 'n' go should hit all the performance modes and give you enough 
experience / heart attacks to work out the bugs.

> #3.5:  okay so I lied, there are actully four items:  a member of my local 
> car-guy support group has cautioned me not to keep the engine at constant 
> RPMs for a long time.  He says its good to vary the RPMs.  Why would this be 
> true?  Rings seat better with RPM changes?  Or is he just passing oil?
The phrase I heard was "wear patterns".  You are deliberately trying to 
get all the new parts to wear together over their performance range, not 
just in the highway cruise mode.  It's not just seats, I think, but the 
cam/lifter combination as well.

I think the parts seat >faster< with RPM changes.  If you went out and 
drove 500 highway miles at 3500 RPM, (less 2 gas stops) you'd have about 
6 hours at that one RPM, and only a few minutes at the other ones.  So 
you'd be 6 hours behind in creating the "wear patterns" for the other 
power settings.

(I'm tossing salt over my shoulder, crossing my fingers, and rubbing my 
Lucky Rabbit's Foot as well as varying my RPMs.  And you know, Lucky the 
Rabbit hates it when I do that).

John M. Trindle     | | Tidewater Sports Car Club
'73 MGB E Stock     | '69 Spitfire E Stock | '88 RX-7 C Stock

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