Ignition, Timing and electronic Distributors

[ashcloud]

Gents, this our place to continue the very important and often wrong settings for ignition timing on the MK2.
I for example had an XJ6 dizzy installed which was 12 degrees behind the original MK 2 that was part of the original equippment.
Now I have the 123Tune which is programable via a USB port and my dear friend Horst has the same for his 4.2 Liter E-type (Ser. 2).
Over the next few days please post Your set-ups and experience to see what can be improved.
Bernhard

[Martec]

I've been looking through the old information I had on the ignition timing and found 2 scruffy bits of paper, also the expensive dizzy and my copy of Des Hamill's book are both dated 2001, wonder if they were set/talking about leaded or unleaded settings. Also the ignition map for petrol on my ECU is not the same as the scruffy bits of paper!

So I'll be jacking the car up soon (it's warmer in the garage) and get the boss to drive it whilst I get the advance angles from the strobe to reset my ECU. Should be interesting to see as the car went very well on this distributor and petrol and it got to 22mpg on a long run.

Best wishes

Brian

[ashcloud]

One word of warning (that I constantly ignore): never mess with a good working system.
I started messing with the brakes and now I am down to a severly leeking brake master. My fault, but mess with the ignition only if You honestly believe that there is definitely room for improvement.
I should have better values by next week testing different curves.
Bernhard

[ecosselynx]

Hi

I haven't checked my timing for a while, but it can't be far-off. for the trip up through France I had 20.8, 21.0 and 20.9 MPG per tank full running at 2600RPM where possible.

[LHR]

All,
This thread seemed to end rather abruptly in March, 2014.
I have a 1964 MK2 3.8 MOD 8:1 compression. I am installing a 123 ignition JAG 6-R-V unit. I have read as much as I can find about the subject of maximum advance and I found this thread and its predecessor to be very helpful - especially the contributions from Piman, Ashcloud and Martec. I plan to start me engine in the next few days after its rebuild. The engine was run-in briefly (not on a rolling road) with the 123 unit with no vacuum connected. It is currently on the number 2 clickable setting. Now the engine is back in the car. New coil, new plugs, new ignition wiring etc.

My question revolves around the subject of the source for vacuum advance. I believe I recall that Brian mentioned in a previous post that he was using a manifold port rather than a carb port for his vacuum source, but I am not sure on what car? My engine rebuilder has come to the conclusion that it is manifold vacuum that should be used rather than carb vacuum, although the 123 installation instructions specifically indicate the use of carb porting.

I have done some follow-up research and I found one article that advocates for the use of manifold vacuum to be pretty convincing. I have attached the article for your review.

I am interested in thoughts and comments from the group.

Lin

http://chevellestuff.net/tech/articles/ ... nifold.htm

[piman]

Hello LHR,

firstly the vacuum advance is designed to improve economy at cruise, and is combined with the carburettors being set lean for that portion of the engine speed. To me as manifold vacuum is high at idle then it is wrong to connect the vacuum advance to it. The carburettor port is there purely for the vacuum advance, nothing else. Note that the vacuum units all look the same but they are not, the set of numbers on the body identify the parameters of the unit and should be as originally specified.
You won't go far wrong by setting these tuneable distributors to the specifiocation of the original distributor as a lot of effort was made in setting them up at the factory. The only difference is that petrol has changed so a variation on the timing is probably required, but the curve is dependant on the engine characteristics, i.e. the overall curve should be correct just advanced or retarted from original.

Alec