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Re: Overheat at high RPM's

To: Mike Nelson <mnelson@tconl.com>, Spitfires
Subject: Re: Overheat at high RPM's
From: Atwell Haines <karbuff@optonline.net>
Date: Sun, 29 Apr 2001 22:27:36 -0400
At 12:16 PM 4/28/2001 -0500, Mike Nelson wrote:

>... when I described the
>problem about the temps climbing at 3000 RPM and greater, they immediately
>said it was timing.
>
>Well, I borrowed a timing light, and it tested at 20 degrees BTDC.  Specs
>say 10 degrees.  I adjusted it, idle has gone down to 700, pickup and
>acceleration seem to suffer a bit.  Temps still rise.. drats.

Mike, does your distributor diaphragm capsule work? (watch the timing as 
you apply vacuum to the line going to the dizzy---it should change)

Also, at 3K your mechanical advance should come into play...disconnect the 
vacuum line and rev the engine, it should change there also, just from the 
mechanical advance.

If either of those components are functioning poorly, the idle timing could 
seem right but the advance at high RPMs could be off.


>What next?  Mine is a front leaning electric fan version, '79 Spit.  I
>removed the entire front bumper to eliminate the lack of airflow issue.
>Thermostat has bee replaced to a 160 degree.  Timing has been adjusted. 
>.  Any other ideas?

I wasn't following your original thread, but are all of the radiator 
valences installed?  The one under the radiator (attaches to the front 
spoiler) is critical for cooling at speed, and since they were made from 
cardboard, they often deteriorate or become missing.

How hot does the engine run at 3000 RPM? If you are driving "spiritedly" 
(high revs at a relatively low speed) the engine will need the fan to cool 
it, and the fan cuts in at just over the 3/4 mark on the gauge.

Regards

Atwell Haines
'79 Spitfire
Succasunna, NJ USA

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