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Re: RPM's

To: "Plant, Keith Contractor (NSAGAETA 60)" <>
Subject: Re: RPM's
From: James Nazarian Jr <>
Date: Thu, 14 Jun 2001 09:44:20 -0600
I wouldn't call it strain so much as I would say that it is just starting to 
There isn't anything wrong with letting it run all day at 5500 if you could 
somewhere to sustain it.  The redline is the point that the engineers have 
determined that you should stay below.  Don't sweat anything below that.

Your numbers don't sound right though.  the car should be geared to do 18 miles 
per 1000 rpm in fourth, so that is 81mph at 4500 rmp.  I wouldn't worry about 
the sound of the engine, but I would investigate why your gearing appears to be 
low.  First thing to check would be the tire size.  I'd also make sure that your
speedo is accurate, either by comparing it to other cars (i.e. keeping up with 
traffic on the highway) or by timing yourself against mile markers on the 

James Nazarian Jr
71 MGB roadster
71 MGBGT-V8 in need of paint
01 Impreza 2.5RS

A complex system that does not work is invariably found to have
   evolved from a simpler system that worked just fine.

On Thu, Jun 14, 2001 at 11:59:00AM +0200, Plant, Keith Contractor (NSAGAETA 60) 
profoundly declared:
> I'm usually a silent list reader, but let me throw my hat into the ring.  I
> purchased my first MGB ('69) in November of last year.   Tach'o yellows at
> 5500 and reds at 6000 rpm.  The car has overdrive.  My question is this...
> When I'm driving, I usually change gears at about 3000, maybe 3500 rpm as
> this is when it sounds as if it's beginning to strain the engine.  In my '97
> Mitsubishi Mirage, it's about the same, maybe 4000 tops.  The problem is
> that by the time I'm in 4th gear at 3500 rpm, I'm only cruising at about
> 40-50 miles an hour.  If get the rpm up to 4500, the engine sounds like it's
> really straining and I only just break 55-if I'm lucky with tail winds, 60.
> This happened both before and after I had the engine converted from leaded
> to unleaded and rebuilt.
> Any suggestions?
> Keith
> '69 B enjoying Coastal Italy

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