Lotus Elan

Ignition timing

PostPost by: Uboat » Sat Nov 09, 2013 10:32 am

Hi all,

I find a lot of ideas for timing curves on this forum, but not so much about actually adjusting the ignition timing. As I had the engine out and would now like to start it up, I have found thet the ignition timing is way wrong. How do you actually adjust it? I know how to find the TDC, but not how to get the spark to 12 degrees prior to TDC on cylinder one

(My car has a pertronix ignitor distributor)

/Ulf
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PostPost by: billwill » Sat Nov 09, 2013 11:06 am

Did any instructions come with the Pertronics?
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PostPost by: billwill » Sat Nov 09, 2013 11:08 am

I haven't read it all through yet, but a topic was posted last year with pretty pictures.

lotus-electrical-f38/how-static-time-pertronix-similar-t26882.html
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PostPost by: billwill » Sat Nov 09, 2013 11:20 am

I see that I had some reservations about that method, but I found a different description on a different website that looks good and just needs a lightbulb


http://www.ttalk.info/PertronixStaticNeg.htm
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PostPost by: Hawksfield » Sat Nov 09, 2013 11:56 am

Hi Ulf

A rough first setting can be achieved by setting the engine to 12 degrees on the timing marks, switch on the ignition and swing the dizzy listening for the crack in the cap. this will give you a start. then you can adjust whilst running.
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PostPost by: Uboat » Sat Nov 09, 2013 3:19 pm

So I should turn the distributor by loosening bolts attached to block? Well this will not be easy with carbs on...
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PostPost by: Galwaylotus » Sat Nov 09, 2013 4:09 pm

Uboat wrote:So I should turn the distributor by loosening bolts attached to block? Well this will not be easy with carbs on...
/Ulf

No! Leave the screw that goes into the block (upper left of the picture) alone, Just loosen the clamp. The clamp screw (lower right in the picture) has a slotted hex head so use either a stubby screwdriver or a small box spanner. Just loosen it enough to be able to rotate the distributor but not so much that it rotates too freely. Once you have the advance you want it's just a matter of tightening the clamp screw so it doesn't rotate. :wink:
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PostPost by: twincamman » Sat Nov 09, 2013 5:19 pm

Ok ....1...find top dead center on piston 1 ......see that the crank pulley is at zero marked on the pulley and the front cover ....move the pulley mark to 5. Degrees ....2place the distributor in the hole and put the. Rotor to point to eleven o'clock and the body of the distributor with the wire receptacle to the front of the engine and the wires pointing to the rear....the dist should drop into the proper gear slot rotating slightly....now replace the dist cap and the power to the dist lead ..turn on the ignition .3 put a spark plug in number one plug lead and lay the plug on the valve cover now rotate the dist until there is a spark ....remove the dummy plug and hook the lead back up to the plug in the engine .....that will get the car started then set the timing to the required timing mark with a timing light .with the pertronics system do not leave the power on more than. A minute without turning the engine over or the halls effect will fail it has been my experience
Last edited by twincamman on Sun Nov 10, 2013 9:34 pm, edited 1 time in total.
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PostPost by: billwill » Sat Nov 09, 2013 5:48 pm

Galwaylotus wrote:
Uboat wrote:So I should turn the distributor by loosening bolts attached to block? Well this will not be easy with carbs on...
/Ulf

No! Leave the screw that goes into the block (upper left of the picture) alone, Just loosen the clamp. The clamp screw (lower right in the picture) has a slotted hex head so use either a stubby screwdriver or a small box spanner. Just loosen it enough to be able to rotate the distributor but not so much that it rotates too freely. Once you have the advance you want it's just a matter of tightening the clamp screw so it doesn't rotate. :wink:



When you tighten the clamp again, do not do it up very very tight. That has been known to fracture the bottom of a distributor.
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PostPost by: twincamman » Sat Nov 09, 2013 5:53 pm

As an aside the dist will come out with the rotor cap and rotor removed with the carbs in place ...Ed
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PostPost by: Galwaylotus » Sat Nov 09, 2013 8:45 pm

twincamman wrote:As an aside the dist will come out with the rotor cap and rotor removed with the carbs in place ...Ed

through the clamp! My first attempt was to remove the clamp and distributor together. What a pain! Lack of sight was a contributing factor so if I can stop someone else making the same mistake I'm happy. :D
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PostPost by: twincamman » Sat Nov 09, 2013 9:56 pm

Correct ...and make sure the dist is seated back in the clamp correctly before tightening the clamp . ..up scope ...vas is Lus New York harbour?.
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PostPost by: Uboat » Sun Nov 10, 2013 2:48 pm

So I put the pulley mark at 12 degrees to tdc, then rotor was six o clock which is in the middle between cylinder one lead and next cylinder lead. So I turned the distributor 45 degrees anticlockwise to get spark in cylinder no 1, then tightened clamp. But the spark was at the same timing! What did I do wrong?
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PostPost by: twincamman » Sun Nov 10, 2013 7:08 pm

I see the problem?....I assumed you had removed the valve cover and aligned the cam marks opposite when setting the crank pully ...........did you do this ???? If not go sit on the naughty step
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PostPost by: billwill » Sun Nov 10, 2013 9:20 pm

Uboat wrote:So I put the pulley mark at 12 degrees to tdc, then rotor was six o clock which is in the middle between cylinder one lead and next cylinder lead. So I turned the distributor 45 degrees anticlockwise to get spark in cylinder no 1, then tightened clamp. But the spark was at the same timing! What did I do wrong?
Ulf


Not sure if that would work. you have to get the rotor arm in the right place first. If you have removed the cam sprockets since it last worked, when you replaced the timing chain it might not now be on the same teeth of the shaft that drives the distributor.

So you may need to unclamp and lift up the distributor, them rotate the rotor arm to near the correct position, then slide the distributor in. When the spiral gear at the bottom of the distributor meshes it causes the rotor to move a bit, so you may need a few attempts to get it in the right place relative to spark plug 1's contact in the distributor cover.

If you look at the rotor arm you will see that it has a long curve on the high tension side that gets close to the spark plug contact, that long curve copes with the automatic advance i.e the tiny spark between the rotor arm and the HTlead contact will move along that curve as the RPM increases. So at static timing measurement it has to be one of the ends of the rotor arm contact that is near the HT contact. Of the top of my head I'm not sure whether that should be the leading edge or the trailing edge of the rotor contact and it is a bit mind twisting to try work it out. It's usually quicket to just try both ways :D

With the simple rotor arm (the one that does NOT have the centrifugal rev limiter built in), the curve of the contact on the rotor arm is quite long, so it is probably OK to just ensure that at static timing point the No 1 contact is near the centre of that rotor contact.

The distributor cam has only 4 lobes, but I think the spiral gear may have 8 or 12 teeth, so for each good position of the spiral gear there are one or two positions that are not right.

Image

Looking at that picture, I count 10 teeth on the spiral gear.
Last edited by billwill on Sun Nov 10, 2013 9:33 pm, edited 1 time in total.
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