View single post by subwoofer
 Posted: 05-08-2016 08:58 am
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Joined: 04-01-2008
Location: Sandefjord, Norway
Posts: 591
I have been shortish in the messages because I had to type on a phone and not a computer. Had forgotten the password to this site and the password reset doesn't work because it send to the email you initially registered from. That address was disused 6 years ago...


Battery: Functioning but getting old (mfg 06) and seems weak. I don't have too much cranking time left in it when the engine starts playing games.

Alternator: It is only ten years old, just changed before I bought the car and looks good. The charge light goes out like it should after starting, but I haven't had time to investigate further. It is a suspect due to seeing that it is dropping the voltage down at idle when warm.

Overheating: Doubt it. Electric fan directly on the radiator, needle rock steady. Due to a production error on the water pump I am measuring at the water rail below the carbs (Dell'Orto) but I think Lotus used to measure there.

Tach: current drive, have the kit to make it voltage triggered. Trouble getting a round tuit...
Jumped the coil feed off another circuit for testing, apart from seeing a lower voltage drop battery -> coil, no difference in behaviour.

Idle speed: Principally set by ear, reading about 1k on the dial. Does not sound like a 700 RPM idle. Incredibly difficult to set idle speed when warm, either it stays where it is or it revs up to 1500-2000 (by ear), probably due to advance kicking in.

Idle mix: 3 turns out to 4.5 turns out makes no difference to behaviour really, apart from the smell of the exhaust. Wideband lambda meter is on the todo list.

Distributor: Mech advance only unit, true state unknown, but looked fine when installed 6 years ago when I changed the engine. Pertronix Ignitor II unit installed. Plug leads are blue silicon leads, probably installed just before I bought the car. Major PITA to get to the dizzy. :-(

Coil: 4 year old Lucas Sport (gold) coil. No visible damage, estimated temp when I have problems ~60C (can hold it for about three seconds before it's painful).

Ways forward: What I haven't done, but is worthwhile is to swap batteries when it is dying. Pull into the yard, wait for it to die (usually within seconds of falling into idle), attempt a start on the old battery, that failing - connect the new one and see if it fires. If it does, the voltage while cranking is too low to get reliable spark. A relay sending voltage straight from the battery to the coil is also something that cannot do harm.

The end result is still that I have been having ignition trouble with this car since day one, it is time for computerized crank fire. But that takes some time to build, so that will be next season...