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[TR] TR vac advance (part 1.)

To: triumphs@autox.team.net
Subject: [TR] TR vac advance (part 1.)
From: CarlSereda@aol.com
Date: Sat, 16 Sep 2006 21:02:13 EDT
Hi listers,
I sent this out last week but doesn't seem to have made it (too long?) - so 
sending in 2 parts now.
-----------------------------------------------
Hi all,
I believe this to be the last word from Leyland Triumph on 
TR4A and Spitfire MK.3 distributor specs; (I'm guesstimating it was published 
in 1968)

WORKSHOP MANUAL SUPPLEMENT for Spitfire MK.3 and TR4A:
1st Edition
Incorporating Emission Control Equipment

Engine Modifications - TR4A
The specification for the TR4A remains unaltered except for the following 
details:
1 CARBURETTOR
a) Needle -  New needle fitted to provide a weaker mixture
b) Main Jet - A new main jet is fitted to suit the revised needle
c) Piston Damper - The piston damper is modified to restrict movement of the 
barrel. This provides a more immediate effect on the piston to give maximum 
accerleration with the weaker needles and jet settings
d) Throttle Disc Poppet Valve - This is a small spring loaded poppet valve 
set in the carburettor throttle disc. At high manifold depression, that is 
during overrun with throttle closed , the valve opens to supplement the volume 
of 
fuel/air mixture which, together with a retarded ignition setting, maintains 
correct combustion.
2. IGNITION DISTRIBUTOR
The system includes a special distributor which has an extended operating 
range to permit a retarded static setting whilst maintaining the normal advance 
characteristics at higher engine speeds.

TIMING MARKS
TR4A  Idle Speed RPM = 850/900,  Ignition Static (Crankshaft Degrees) = 
T.D.C., Ignition at Idle = T.D.C.

Ignition Distributor Data
Centrifugal advance (check at decelerating speeds)
Distributor RPM Degs. distributor advance   crank rpm   degs. cranshaft 
advance
below               min         max         below       min         max
400             no advance to occur     800
500             0           3.5             1000        0           7
700             7           10.5            1400        14          21
900             11          13.0            1800        22          26
2500                11          13.0            5000        22          26

(* cont.)


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