Strange Timing Advance

[Galwaylotus]

I've had the weather and time to drive my S3 SE a bit this week. I find the engine hesitates and bucks on partial throttle until it's well warmed (about 8-10 miles). I figured it needed a tune so, after changing the oil and filter, I got out my adjustable timing light and got the car running again. I should have a 40953 distributor with an advance curve starting about 1000 rpm and continuing to advance up to 24? (plus static timing) at 6500 rpm. I was getting total advance of about 34? or 35? from 2500 rpm. That seems more like the 41189 or 41225 distributor characteristics than my 40953. My casing, at least, is correct as it's marked 40953. I don't really know what's going on here. If I was in the UK, I'd bring it to one of the respected Lotus shops to get ignition and carburetion set properly but in the west of Ireland I don't know of anyone who really knows these engines.

[gjz30075]

It's possible a spring broke and the weight is totally advanced before it should be. Might be time to pull the distributor to check springs and weights and to verify you really have the 40953 specs.

Greg Z

[ricarbo]

scan0001 Lotus distributor.pdf

(160.19 KiB) Downloaded 449 times

Whilst doing some filing, I found this. Which states the distributor plate should be stamped 12 degrees. I think the graph is wrong as it shows the advance curve start at 0 rpm, but i think there should be no advance until a certain speed is reached.
Richard