2.25p Timing question

[jperkinson]

Hello All-

I posted this on other boards but was not able to get a response... Perhaps someone here might have some insight...

I am trying to more closely examine what the ignition timing curves for the 2.25p engine should be. I have a newfangled electronic ignition system (MegaJoltLite Jr.). On the forum there, someone had already done some work with a Landy 2.25 in the UK and uploaded his 'ignition Map'. I have attached a screenshot. This map is presently installed and appears to work fine on my rover, a little hesitation when you slam on the gas, but it picks right up... (I have not done extensive road testing, just quick circles around the block).

I have no frame of reference, but there is almost 60 degrees of advancement at 4500 RPM (and low load). Does this sound right? Is there a written source on what this should be (approximately)?

-Thanks
-Jim P.

http://images.yuku.com/image/jpeg/dc536cfe1f455b634ea3a83de14c5e076dd50baf.jpg

[StX_Rovers]

60 degrees at low load does not sound that unusual. This is if you mean by low load steady state cruising with the throttle fairly closed. Essentially, this is a situation with relatively high intake vacuum. A typical distributor might have 35-40 degrees of just mechanical advance in it, between initial timing and centrifugal advance. Add in vacuum advance, which is likely to be another 15-20 degrees and there you go, 60 degrees. The advance should drop when you nail it at that RPM, though.

Bog on acceleration can be a sign of a bit too much advance or it could be a lean condition in the carby. Does this hesitation only happen when the engine is cold, but not warm? That indicates it is a fuel, not ignition issue. Essentially, the engine when cold is not getting enough of a a shot from the accelerator pump. If the hesitation is not there when it is fully warmed up, then I would not worry about it. If the hesitation does not seem to be temp related try pulling a bit of the advance out.

Listen carefully for pinging if you are worried about your advance.

Sound slike a neat system, I have not heard of it. Do you have a link to a website?

Good luck.

best regards, Dave

[jperkinson]

Hi Dave-

Thanks for the information, I'm glad to hear this is in the realm of realism.

I haven't had time to dust the rover off this week, but I will be sure to listen to see if the hesitation goes away after it is warmed up. It could also, very easily be the timing. I spot welded on the timing trigger wheel, and wasn't as precise as I could have been. But it seemed to kick over and work ok, so it's possible I am off by 1 or 2 degrees there. I should be able to compensate for any offset in the trigger wheel by lower or raising the entire ignition map by one or two degrees. That would be a fun experiment.

The system is the Mega Jolt Lite Junior... version 4. The website is here: http://www.autosportlabs.net/Main_Page


It was an easy installation, and the parts were a breeze to get. The only thing I couldn't source in my town was the trigger wheel, which I bought new to fit the 2.25 crank.

It was also cheaper than rebuilding my broken 24v system.

-Thanks again.
-Jim P.