Triumph Repair: no vacuum, triumph tr 6, fuel vapors

Question
QUESTION: Hi Howard, my 1979 spitfire has no vacuum to the distributor! All hoses the to the carburetor, and to two other devices are not plugged. I have no idea what those things are, and what they are supposed to do! Any advice is appreciated!

ANSWER: Hi Steve,
"Two devices are not plugged" ????? Your description of the two devices is a little vague. You need to take a picture of the two "Devices" and maybe I can tell you what they are.

Vacuum to the distributor is usually off of a port on the carburetor flange (ported vacuum - vacuum only when the throttle is opened) Also some Spitfires operated their EGR valve off of the same ported vacuum.

Send me a picture of the "Devices" and I will try to ID them for you.

Howard

---------- FOLLOW-UP ----------

QUESTION: Hi again Howard, I checked for vacuum with the motor at idle speed, I did not know the throttle must open to obtain a vacuum! One device is a flame trap, and the other is an EGR valve, and both operate off a ported vacuum! The EGR valve has a slot on the top for a screwdriver, but I did not want to force it, or break it! Can it be adjusted, and if so, how? You are a source of great information, and helped me much in the  past.  Thank You,
         Steve

Answer
What is commonly called a "Flame Trap" is in a vacuum line to trap and condense fuel vapors so raw fuel does not migrate to a vacuum diaphragm and cause problems. Only vacuum off of the carburetor flange is "Ported Vacuum" Vacuum off of the intake manifold is called "Straight Vacuum" and that is used on different models and different years to do other things. The Triumph TR-6 sometimes used straight manifold vacuum to a Vacuum retard unit on the distributor and they also had a model with both on the same distributor. A vacuum advance unit powered by ported vacuum and a vacuum retard unit powered by straight manifold vacuum.

I don't remember any Spitfires having a retard unit. The method to tell if a unit is a retard or advance unit is to follow the path in the vacuum line through the diaphragm into the distributor and if it goes around in the direction of rotation of the rotor it is a vacuum advance unit. But if it goes in and is against the rotation of the rotor it is a vacuum retard unit. The exception to this is when they put the port for the vacuum hose on the wrong side of the diaphragm.

The EGR should not be tampered with other than sometimes you can clean one that is coked up with carbon by removing it and reach in and lift the valve manually and sand blast the port hole with a sand blaster or plug cleaner.

Howard