TC Timing Marks

[Galwaylotus]

I have the Elan factory shop manual with a drawing of the water pump/timing cover. I also have a photo of the same cover I got from the internet at some point. Here's my problem. Both of the above sources show four timing marks - TDC, 10, 20, and 30? BTDC. My TC has only three marks and there are no labels cast into the cover. Has anyone seen this before and how do I determine what each mark references? I bought my Elan a year ago, drove it home 500 miles, and on my first trip afterward it stopped and I haven't been able to run it since! I can only work on it in the street and the weather has been dire so it's taken me far longer to try and sort it than I would have liked. I have the Webers off and want to set the static timing before trying to reinstall them. Help please! I want to drive my Elan!!!

[RotoFlexible]

Someone else will verify this, but I believe the early timing case front covers only had marks at TDC, 10 and 20 BTDC. Generally speaking, setting the static timing at 10 BTDC should get you running. Good luck!

[Galwaylotus]

Thanks, Andrew.

Anyone use a dial back timing light on a standard Lotus TC ignition? I've read that the timing cover marks are not accurate so if I can determing TDC can I use a dial back light to set my timing accurately?

[handi_andi]

Hiya
I brought a new electronic Lucas dizzy off Tony Thompson Racing and asked them about ignition timing and what to said the static too. The basic instructions from them were to get it going then set idle to about 5000rpm and turn the dizzy till the engine just started pinking then back off a couple of degrees and that was the timing done. Has anyone else sued this method?
Andy

[69S4]

Thanks, Andrew.

Anyone use a dial back timing light on a standard Lotus TC ignition? I've read that the timing cover marks are not accurate so if I can determing TDC can I use a dial back light to set my timing accurately?

I've not been that impressed with my (old) Gunsen dial back light. I tend to use it now with the dial back at zero, ie as a normal light because the dial back calibration on the knob doesn't seem to correlate with what I see on the timing marks. Dialing in 10 degrees of advance on the light doesn't move the timing marks 10 degrees - more like 7-8. Makes me wonder if the advance calibration is wrong is it even accurate at the zero point? I use it because I've got it but if it broke I'd replace it with a low tech one.

Regarding the accuracy of the timing cover marks, some time ago I checked mine with a dial gauge reading off the top of the pistons and found that, for my engine at least, the tdc mark was pretty much spot on.

I would have thought that for the purposes of getting the engine running, a pencil through the plug hole resting on the piston top would identify which mark is tdc and then timing to a static setting of 10 degrees btdc would be good enough to get you going.


Stuart

[Galwaylotus]

I would have thought that for the purposes of getting the engine running, a pencil through the plug hole resting on the piston top would identify which mark is tdc and then timing to a static setting of 10 degrees btdc would be good enough to get you going.
Stuart

I agree that it would be close enough to get the engine running if I started with 10?BTDC static timing. I can also assume the most clockwise mark is TDC but with only three marks can I assume that each is 10? apart as on the four mark cover? I'd like to be a little more certain!

[handi_andi]

How about putting a protractor against the front pully?
Andy

[Galwaylotus]

That would be good - if the engine was out of the car! It's almost impossible to see anything down there with it installed.

[handi_andi]

Now the feeling, have taken to sighting the timing marks down the dip stick pip which seems conveniently located with 10degrees. When I posted I did think about advising a mirror as well. How about a circular piece of wood with 10degree segments marked on side thus creating a thick protractor that can be read from above?
Andy

[Foxie]

Hiya
The basic instructions from them were to get it going then set idle to about 5000rpm and turn the dizzy till the engine just started pinking then back off a couple of degrees and that was the timing done. Andy

IMHO, to use a 'no load/idle' throttle position, even with it wound up to 5,000 rpm as the set point, will definitely result in 'pinking' (detonation) under full throttle.

Better to use tried and trusted settings, or if you want to experiment, do it on a rolling road under full load

[69S4]

I would have thought that for the purposes of getting the engine running, a pencil through the plug hole resting on the piston top would identify which mark is tdc and then timing to a static setting of 10 degrees btdc would be good enough to get you going.
Stuart

I agree that it would be close enough to get the engine running if I started with 10?BTDC static timing. I can also assume the most clockwise mark is TDC but with only three marks can I assume that each is 10? apart as on the four mark cover? I'd like to be a little more certain!

Attached is a picture showing the three mark timing cover -

[frearther]

can I assume that each is 10? apart as on the four mark cover?

Yes. I just changed front covers (to the cartridge type), and the four timing marks on the new one (0,10,20,30) are the same spacing as the three marks on the original cover.

[rgh0]

Hiya
I brought a new electronic Lucas dizzy off Tony Thompson Racing and asked them about ignition timing and what to said the static too. The basic instructions from them were to get it going then set idle to about 5000rpm and turn the dizzy till the engine just started pinking then back off a couple of degrees and that was the timing done. Has anyone else sued this method?
Andy

Hi Andy
I set the timing on a rolling road looking for maximum power before pinking in the 6000 to 7000 rpm range in a competition engine. On the eninges I build running on Avgas at around 12:1 compression ration this results in around 32 degrees max advance. The dizzy is set to have 20 degree advance so this results in around 12 degrees static that gives good idle.

Setting the maximum advance at no load and 5000 rpm by pinking for a stadnard advance curve dizzy and then backing off a couple of degrees is a rough approximation of the above and probably gives an Ok outcome.


Typical maximum advance for a Weber road engine is in the 25 to 28 degree range if you get outside that range by any method I would start to worry if somethng else is wrong.

cheers
Rohan

[Galwaylotus]

Thanks, guys. That photo was just what I was seeking. I've added a copy to my shop manual. The verification of 10? steps gave me the confidence I needed. I have checked TDC by using a dial caliper and it seems it was spot on. I've now set the static timing to 10? BTDC and verified it by rotating the crank through 720? and the light came on right at the 10? mark! Next step is to refit the carburettors. That should be fun with the engine in the car!!
Anyone have an easy method for getting the spring washer gaps correct while the engine is in the car?

[handi_andi]

How about using a so called 'go-no go' gauge. basically a block of hard platic or metal cut to the correct size, it it slips in easily then nuts need tightening, if won't go in they need backing off. Kinda like a feeler gauge when doing tappets. Think I might try it myself when I get the head back on

Andy