I attempted to take my 67 340 for a short drive yesterday but could not due it running very rough. It has always started pretty easily but not so yesterday. After it did start the idle was ragged and after the car warmed up some it began back firing through the exhaust. I have a manual switch to control the starting carb. A friend of mine who also has a Mark 2 thought maybe the starting carb was flooding the engine even when the switch was turned off. Is there a way to trouble shoot the starting carb to see if indeed it is flooding the engine? Sorry for the questions but I'm still not that familiar with exactly how it works and how to diagnose problems.

 

From my experience with the AED it is very susceptible to ambient temperature changes. On the top of the AED there is a needle with a locking screw which allows you to adjust the needle height. I have found that as the temperature changes from summer to winter the needle needs to be adjusted to either weaken or enrichen the mixture so compensate for the change. There is no set point what I found was to start the engine then take hold of the top of the needle and pull it up until the desired idle speed is achieved then adjust the locking screw to hold it in position. The needle is difficult to pull up at first as there is quite a vacuum pulling the needle down but there are no moving parts that you can harm yourself with.

 

Backfiring through the exhaust. Are you sure that the distributor has not come loose & that your rotor is correct & not falling apart or earthing to the shaft. Some bad rotors out there especially the ones with a Rivet holding the arm. Correct Rotor ultrasonically welded.

NOS Lucas.


New ~ can't jump to shaft, only cap.



Do you have a strong fuel smell at the starter carb?

Is your fuel tank breather open. & not blocked. Easily checked by removing the fuel cap. These are such low pressure systems at approx 3 psi that any fuel restriction causes trouble. Don't ask me. Experienced the same thing on my left tank.

 

I've pulled the dizzy and waiting on new points. I'll check the timing when It's back in. Not sure of gas smell around starting carb as the hood was shut and the engine would not stay running unless i had my foot on the throttle. Tanks vent is open.

 

If you are pulling the dizzy and putting in new points it is also an opportune time to replace the condenser. They do decay over time.

A question.
Did you have any fuel deposited on the floor? SU carbies are notorious for sticking float/needles if the float bowl dries right out and will dump fuel via the breather pipe. A solid tap on the float bowl will free this.

The starting carb is a simple device and unless the spring under the solenoid is broken, I doubt if it is the problem

 

The "new" Viton coated needle tips improve this situation. If ever pulling the carbs apart to adjust float levels etc. I advise changing the needles while you are about it if you don't have the Viton coated ones..

Available as a needle & seat kit which I would advise. You can buy the needles individually should you wish.

But they can still stick on occasion & listen to Bill.

Those of us that enjoy the audio game do condenser/capacitor changes on a planned basis as a service item. They dry out, swell & suffer other maladies especially in output stages from the transformer/s & switch mode power supplies where they run hot. Whichever system is used. Some of us do entire capacitor changes in the whole amplifier. And yes you can hear the difference. Same goes for your capacitors in your ignition system.

 

Indeed, swapping out capacitors was always a default first step in restoring old electronics as well as in maintaining traditional coil and contact breaker ignition systems.