I've read all the comments about the function of the starting carb and to be honest wasn't able to digest it all. I do have a couple of questions though. I just now started my 3.4 Mark 2 and was planning on taking it for it's maiden spin around the block but was concerned about making it back home. I backed the car out of the garage and let it idle for say 5-6 minutes or until the temp came up. At about the time I decided to leave it started running ragged, back fired through the exhaust and died. This is exactly the problem my friend was having with his. It seems the starting carb did not shut off and flooded the engine. I'll wait a bit before I try to re start. Am I thinking correctly? The fix is to run a wire from the hot side of the starting carb to a switch to be able to shut it off? Next question is can one install a manual choke of some sorts and do away with the starting carb? I've read someone has done this.
As always thanks.

 

Check Distributor & rotor. What you describe should never happen even if the starting carb does not shut off. You should merely get brown turning to black smoke from your exhausts.

https://www.jaguarforums.com/forum/m...n-only-262651/

 

Using a manual switch to by-pass the otter switch is a good idea, that way you know the AED is off when it needs to be off.
I have a manual switch on my car, I never liked the otter switch, it can shut the AED off too soon and the car has a tendency to stall, or it will stay on too long and the engine will run rich.

For now do this test:
Start the car from cold, the otter switch will enable the AED as it should, and give you a fast idle.
Let it run for 5 to 6 minutes or even 10 minutes to make sure the engine is warm enough to run with out the AED.
Pull the wire from the otter switch, this will take the AED out of the picture and the engine will (should) return to a normal idle (should be at 600 rpm, or a little higher like 8 is OK)
Very gently drive the car around the block as it is still a little cold and you may stall it if you let the clutch out too aggressively with a heavy foot on the accelerator.

If it makes it around the block with out back-firing, then drive it until it reaches normal operating temperature.
Also, if it does not back fire, then you can assume that the carbs mixture is set correctly and the back-firing is caused from the AED not shutting off, this is due to a faulty otter switch.

Yes, you can install a manual choke, but it requires some majour surgery on the carbs as they will have to be removed to add the choking device.
See the second photo in post #3:

https://www.jaguarforums.com/forum/m...0/#post2110443

Here it is through Burlen _ pricing has gone through the roof !
It will fit the HD6 as well.

HD8 Jet Housing Centre - SU Carburetters

You will have to rig up a linkage between the two carbs and a cable system so it can be operated inside the car.

It would be easier and less expensive just to set up the carbs properly concerning the mixture and the AED as well.
Start by manually by passing the Otter switch with a manual one under the dash.

Start reading about how a venturi works and understand how that applies to the SU carbs and the AED.
A venturi is the basic principal of all carburetors, not just SU's.
Once you understand that, all of this will make sense and you will be able to adjust things and make them work as they should.

 

Thanks the procedure you listed was what I was after. Can the thermostatic switch be tested? I have another to use just in case.

 

One more thing. Forgive my lack of knowledge but is the otter switch that's mentioned the thermostatic switch?

 

Yes

 

This has all been covered multiple times in other threads pictures & all.

 

I wouldn't even bother, follow my procedure, don't make things more difficult then they have to be, just get rid of it, at least that's what I would do.

Yes

 

It may have been covered Glyn, but in my opinion it has not been explained very well.

 

OK! ~ The entire E Type pull down set up was explained pictures & all includiing Bowden cable & Lever.

 

I don't think that the function of the AED and converting to a switch to over ride the Otter switch has been poorly explained, I just think that some of the topics threads go off track at times and the subject changes. The thread of the topic then gets confused and difficult to read.
The Otter switch can be tested.
The Otter switch is a Bi metal earth switch which is closed when the engine is cold allowing the AED to earth and open when hot disconnecting the earth and breaking the circuit.
To test start the engine and when cold the AED should be making a loud hissing noise because the closed Otter switch is creating an earth. Disconnect the electrical cable running to the Otter switch and the AED should shut off.ie the Hissing stops. Plug the Otter switch back in and the Hissing should start again from the AED. Let the car warm up to normal working temp and the Otter switch opens cutting the earth it should turn the AED off ie the Hissing stops.
The problem with an old Otter switch is that it can lock open or closed so it needs replacing or it opens too soon ie when the engine is not warmed up enough turning the AED off which makes driving the car difficult until it gets to normal temperature. An over ride switch just allows you to control power to the AED and to turn the Otter switch off and on rather than allowing the engine temperature to do it for you.

 

 

Or it doesn't turn off soon enough causing rich running.

 

Over rich running will not cause backfiring down the exhaust ever. Bad timing or incandescent material will.

 

Have you ever dismantled your distributor? With it's centre screw that holds it together. On reassembly it is very easy to get the timing 180 degrees out. Usually the car won't run but backfires down the exhaust. but much depends on where your static timing is. If just set roughly by hand you may get it to run. And remember the rearmost cylinder is No 1.

Frankly I don't think you will get the engine to run but we are exploring all avenues.

 

Timing is good. I have a couple other issues right now to address then back to the AED.