Timing is everything

[rogerch]

My nice shiny new timing light fortuitously arrived this morning. There seems to be some conjecture over how to set the timing, so if I set my timing at 10 BTDC, running at 900 rpm with the vacuum hose disconnected how close will I be ?

I'm intending using the bell housing / flywheel marks set up, any advice, how easy to see the marks is it ?

[Sparky]

Sounds good to me! Grab some Tippex (have they invented that down there yet?) and mark TDC & -10 before starting - it'll be a bitch otherwise. TDC, of course, will be rightmost marker as looking from the back.

[Mike6]

Roger, service manual says to check timing with engine at normal operating temperature to ensure TIV switches the distributor capsule to the throttle edge port. There is no mention of disconnecting the vacuum hose(s). You can see the big pointer through the clutch housing aperture - add a blob of tippex or similar to this. There are a number of markings on the edge of the flywheel so you will need push the car until these appear. The 10degree mark is just to the left of tdc. A blob of tippex on this and its then easy if you adjust at the distributor clamp rather than slacken the distributor itself. The spring loading could otherwise push out the distributor and undo all the good work.

[stevem]

You can also put white marks on the intake and exhaust pullys to get the timing into the right ballpark, TDC is already marked on there with the green dots on your car, from there you can work out 10 BTDC using your 50 year old geometry set from school and it will be easier to see than the flywheel marks. Not accurate, but good enough to check the initial timing setting or allow you to find the rusty flywheel mark which might be invisible like mine was.

[rogerch]

Sounds good to me! Grab some Tippex (have they invented that down there yet?) and mark TDC & -10 before starting - it'll be a bitch otherwise. TDC, of course, will be rightmost marker as looking from the back.

Tippex ? been and gone, we've moved on to new technologies.

[rogerch]

OK need some pointers here. I can see a mark with the timing light, spot on, it seems there are other marks, but this one is the "Highest" "Longest", most distinctive. Am I looking at the 10 BTDC mark. It can't be the TDC mark because the engine wouldn't run that well. Also what is the trick about getting the light in line with the pointer?

[CHANGES]

Roger... you don't have to get the timing light in line with anything, as long as it illuminates the area...it works as a strobe in time with your ignition. ..The mark that is prominent on the fly wheel which is inline with the pointer when the engine at tick over speed specified is your timing angle.....when you move the disty you will see it change... as you say it should be 10 degrees..

As you look at it the marks the one on the right is TDC (not very clear in this pic.but trust me it is) then the increments going to the left are every 5 degrees numbered at the 10-20-30-40 degree points (you should be able to see in pic )

You can just make out the pointer to the right of the crank sensor ( which is not fitted to yours ) It always helps to put a bit of tipex on point for ease of viewing..

Hope this answers your questions...

Dave

[rogerch]

OK, I had this idea of sticking a wire brush down the hole with the engine running to clean up the marks on the flywheel. The traumatic picture of pulling the bell housing off to retrieve said (now mangled) wire brush has put me off the idea. I'm still not sure what I'm looking at.

[CHANGES]

Get the engine into TDC area and rub with emery paper, rotate abit and repeat.. safe. slow. but effective. then paint in or tipex 10 degree mark....

Dave

[rogerch]

Thanks Dave, is that pointer a screw fit, ie can I take it out to clean and paint it ?

[CHANGES]

Yes. may be a bit stiff if original.( bi metal corrosion etc ) to memory M8 thread. with strraight slot screw driver head..

Dave

[rogerch]

Well it's all cleaned, painted marks, all very viewable. My timing is 9 degrees BTDC, seems hardly worth buying a new timing light for. Being as this seems like an exercise in Braille does anyone have any pointers, I'm thinking of removing the plenum, so I can see what I'm doing, ie the clamp on the distributor and adjusting the thing.

[Sparky]

You can get at the clamp quite easily between the carbs. Be VERY careful not to allow the distributor to pop out of its key. I often loosen the clamp only slightly, then move the distributor round using light taps with a screwdriver. You only have to loosen the clamp a tiny bit to get movement on the distributor. No real need to remove the plenum, unless the distributor pops out!

[rogerch]

My first Lotus was an Elan, the twin cam engine also had the distributor well concealed under the carburettors, 1967-1988, in 21 years you would think they could have found a better place.

Thanks for the advice, is there only one way the distributor will go back if it pops out ? ie I can't get it 180 out or something.

[Sparky]

It's an offset key, mate, so only one way.

[rogerch]

'Tis done 9.9 degrees BTDC (close enough)

My thanks kind sir.