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Timing mark on Conquest Century DJ252

ROSS70JEN
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Location: LOOE CORNWALL

Timing mark on Conquest Century DJ252

Post by ROSS70JEN »

HI All
I have tried to see if my Conquest timing is set correctly.
But I could not find the mark on the flywheel by the gear box view hole line up any where near the top of cyl.1.
It looks like the flywheel has been fitted 180 degs. out.
Is this possible ? Or am I going a little mad!!!
If it is Possible should I leave the timing alone ?
What would you Do ?
regards Bryan

pekkak
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Joined: Fri May 13, 2016 7:26 am
Location: Espoo, Suomi - Finland

Re: Timing mark on Conquest Century DJ252

Post by pekkak »

Hi Bryan,
The mark must be there. At least in my DJ252 it is. But it is hidden. I suggest you take a good flashlight and try to find it. Try to look certain angle. I cannot imagine that the flywheel all wrong fitted. Another way is to remove nr 1 cyl spark plug and place a wire or similar in the hole. Then turning slowly try to locate when the piston is in uppermost position. It is better to remove all spark plugs. Turning the engine is so much easier. After locationg the uppermost piston position timing the mark you should see the timing mark.
Any help?
Pekka

Stan Thomas
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Re: Timing mark on Conquest Century DJ252

Post by Stan Thomas »

Hi Bryan,

As the last post says, remove number one spark plug and insert a piece of wire or whatever and turn the engine over on the handle until the piston is at the top of its stroke.

You should be able to turn the engine back and forth "either side" of the top of the stroke to get the piston position accurately at the top by turning the fan blades, although you may need to overtighten the fan belt to do this. There is no need to be on the compression stroke - just number one piston at the top of its stroke. Now look for the timing marks on the flywheel.

If you cannot find them, proceed as follows:

Turn the engine backwards so number one piston descends about one eighth of an inch. Now check the points are just opening. If that is so, it means the ignition is firing about 5 degrees before T.D.C. fully retarded. Its not truly accurate, but at least the engine will definately run as a starting point (pun intended) to setting the ignition with a strobe or vacuum guage.

Note: It was the traditional "British" way of timing engines by positioning the timing marks to set the ignition statically (i.e. fully retarded) - whereas the more modern and accurate way is to set the timing fully advanced with the engine in "real-time" running mode - but that entails the use of a strobe which was not in vogue years ago.

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migray
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Re: Timing mark on Conquest Century DJ252

Post by migray »

This thread viewtopic.php?p=30741#p30741 gives a picture from the workshop manual. The marks on the flywheel are etched into the edge (ie almost at right angles to the viewing hole) and difficult to see. The letters IGN and TDC should be there

pekkak
Posts: 57
Joined: Fri May 13, 2016 7:26 am
Location: Espoo, Suomi - Finland

Re: Timing mark on Conquest Century DJ252

Post by pekkak »

I think it is not only "British way". The method has been used widly all over the world long time ago. :) I have used strobe both in my and my friends old cars. Nowadays there are "electronic brains". Gee! I hope not the only brains in the cars. :lol:

qantasqf1
Posts: 299
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Re: Timing mark on Conquest Century DJ252

Post by qantasqf1 »

Bryan, my diagnosis is that you may well be going mad, but not because of this! The flywheel is fastened to the crankshaft with 6 equally spaced bolts and nuts and since there are no dowels the damnable thing can be fitted in 6 different positions. I hope you now feel a whole lot better.
I shall now lay open to accusations of committing a Daimler solecism. Ignition timing on these older engines with low compression ratios is not as critical as today’s engines. You could do what I used to do in the 60s as a mechanic on BMC, Ford and Rootes cars and set it by trial and error: drive it and see if it pinks with the throttle wide open at a low road speed. If it doesn’t, then rotate the distributor body opposite to the direction of rotation by about 5 degrees and keep repeating until the engine pinks. Back the distributor just enough off until it doesn’t. Done.
I can hear howls of disagreement from the UK here in Australia already...!

pekkak
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Joined: Fri May 13, 2016 7:26 am
Location: Espoo, Suomi - Finland

Re: Timing mark on Conquest Century DJ252

Post by pekkak »

Gee, I didn't know that. My DJ251 flywheel has never been moved. :)
It is going to be very hard Brexit. I am really sad to see you go... :(

Peter Grant
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Re: Timing mark on Conquest Century DJ252

Post by Peter Grant »

Steve,
i thought you were a Rolls Royce Aero engine person, and now you tell us otherwise????
:geek: :geek: :geek:
PG

Stan Thomas
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Re: Timing mark on Conquest Century DJ252

Post by Stan Thomas »

If the flywheel has been incorrectly located on the crankshaft, the answer is simple!

Rotate the engine slowly until you find the "ign" mark on the flywheel. This will align with two pistons - but not number one or six of course. (the positon of the pistons in the cylinder block are in pairs: 1 and 6 - 2 and 5 - 3 and 4).

Assuming the engine is running and you merely want to check the timing, it matters not which piston you check from, or even if it is on the compression stroke - as the cam-lobes on the distributor are 60 degrees apart, so the timing could not be that far out if the engine was running at all.

So with the "ign" mark on the flywheel correctly set - just check that the points in the distributor are just opening. Job done.

However, if with the "ign" mark correctly aligned you find the contact points "between lobes" on the distributor, the flywheel is 60 degrees out relative to the crank throws - so the following applies:

Bring a piston to the top of the compression stroke, time the distributor with the points just opening, then fit the plug lead for that cylinder into the distributor relative to where the rotor points, and then fit the other leads in the direction of which the distributor rotates in the order of 1 -5 - 3 - 6 - 2 -4.

You can even ignore finding compression (which may entail removing the rocker cover etc.) and just time as above - although you could be 180 degrees out and the engine will not start - in which case merely swap the plug leads round in the distributor cap.
Last edited by Stan Thomas on Wed Aug 05, 2020 9:58 am, edited 2 times in total.

qantasqf1
Posts: 299
Joined: Mon Mar 07, 2016 10:13 pm

Re: Timing mark on Conquest Century DJ252

Post by qantasqf1 »

Stan, the crank throws are 120 degrees apart, but the 6 potential positions of the flywheel are 60 degrees apart so there’s no guarantee!
Steve

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