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Re: Pinking Spitfire

To: "Richard Jackson - Network Technician ext. 2570" <RICHARD.JACKSON@nene.ac.uk>
Subject: Re: Pinking Spitfire
From: Julian Daley <j.daley@umds.ac.uk>
Date: Fri, 16 Aug 1996 12:35:36 +0100 (bst)
Cc: triumphs@autox.team.net
Priority: NORMAL
On Wed, 14 Aug 1996Richard Jackson wrote:
> I have a, well it's more of a concern than a problem. My 73 MkIV Pops 
and bangs
> really loudly when I shut off the throttle and the engine is doing alot of the
> braking, ie going down a steep hill in a low gear with my foot of the
> pedal(gas).....Could this be valve timing incorrect, allowing unburnt fuel to
> be sucked out through the valves when it shouldn't be, or am I
> paranoid/clutching at straws/etc.....

Mine started doing that when I replaced the carb throttle plates with
ones without the poppet valve.  I think the purpose of the poppet valve
was to lean out the mixture on the over-run.  So without it you get a
rich mixture under engine braking which I guess causes the lovely
popping noises.

> ps. it does sound quite good, but I am a bit concerned it might be
>knackering something up!!!!

Just enjoy it !  I try very hard to make mine do this under railway
bridges, it sounds even better !  What a big kid.

Julian.
_________________________________________________________________________ 
       Julian Daley, Dept. Clinical Physics, Guy's Hospital, London
___________________________ j.daley@umds.ac.uk __________________________ 



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