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Distributor vernier timing question


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Hi all,

 

Since fitting a Electronic Distributor I want to reset my timing as I am getting some pinking. I have a simple strobe so was planning the following:

 

Set the vernier to 'zero'.

Using the strobe, twist the distributor body to get ignition at TDC.

Use the vernier to advance the timing to 4 degrees BTDC.

 

Please can someone confirm what the timing marks on the vernier scale represent? I have conflicting information. Is it one degree per mark or four?

 

Thanks,

Ian

 

P.S: According to the factory manual, 4 degrees is suitable for >80RON fuel, as we (allegedly) have 97RON available on forecourts, what timings work with a standard engine and modern high-octane fuel?

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I suspect very few early TRs are still using standard heads, cams, carbs, engine capacity etc and fuels now are vastly different to the leaded fuels of yesteryear. In my view the factory settings are a guide only.

With the TR2 I get considerably more performance if the timing is set to just stop any pinging.

So set the timing to about 10deg BTDC and go for a drive. If it doesn't ping advance it bit by bit so that it just pings.

Stop and retard the vernier very slightly. If it doesn't ping that is the best setting, if it does repeat the process until it doesn't.

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Thanks John, that sounds a good plan but do you know what the marks on the Lucas distributor relate to so I can set a baseline?

Ian

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You said you have an electronic distributor, if thats a complete unit such as available on likes of Ebay then the settings of it wont be anywhere near original Lucas. If you only have a electronic pickup in an original Distributor then you will find the starting point for timing is definitely different to original points based and the vernier settings will alter the timing differently too.

Stuart.

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Hi Ian

Yes vernier calibrations are indeed 4 degrees, but don't take them for gospel as they are not 100% accurate take them as roundabout (after all it is Joe Lucas) better to set distributor vernier midships so you can advance or retard during a road test. Timing at idle or static is not that important, what is important is that total advance is correct at around 2500rpm. Nobody drives around at idle speed.

Staffs Man.

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Thanks Chaps!

 

Stuart: Agreed re eBay! I have a Distributor Doctor restored / converted Lucas dizzy, Lucas labelled flamethrower coil and genuine NGK period leads. Only the best for my TR! I would never buy an eBay special. I had one some years back on my S2 Landy and it did not run right. When I got it on a test rig I found that the 4 magnets were not at 90 degree intervals... ! I also bought a set of 'Bosch' spark plugs from eBay that turned out to be very convincing fakes that left me stranded and scratching my head for weeks. eBay needs to be avoided for anything but original second-hand parts IMHO... :)

 

Brian / Staffs man, thanks for the info. I used a piston stop plug to exactly mark TDC on the pulley (which was close but not exactly on the factory drilled hole TDC marker). I made up a disc, the same diameter as the crank pulley and marked 0/2/4/6/8/10/12 degree intervals, then transferred these onto the pulley. I screwed the Lucas vernier right in and moved the dizzy until I was strobing at TDC. Then I wound out the vernier to the first notch and the strobe was pretty much bang on 4 degrees BTDC. I tried the next two notches and got 8 then 12 so the vernier seems pretty reliable, give or take 1/2 a degree either way.

 

For those who are interested in what I ended up setting the timing to; I then warmed the engine up and tested the car at various timings, starting at 4 degrees running the engine under load in 4th from 1000RPM up to about 3000, then advanced the timing in stages to see when it started pinking. Using 97RON fuel I got to 3.5 notches (so a fully-retarded, idle timing of roughly 14 degrees) before I got any pinking. I backed this off to 3 notches (12BTDC) and any pinking was gone, even under full throttle from 20MPH in fourth, labouring up a long slow hill on a hot day with the engine a little hotter than usual (Evens coolant runs at about 190-195F in the current heatwave).

 

I got back and double checked with the strobe and confirmed the idle timing was a nat's under 12 degrees. When I next fill up I might try 95RON and see if it makes much difference but the car picks up really well now and revs cleanly through throughout the range, pulling strongly all the way. I also set the valves to 0.13" ("for high-speed driving" in the Triumph bible) but when it got hot the engine sounds a little too tappety for my liking so I will close them down to 0.10".

 

Thanks again,

Ian

Edited by boggie
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