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More advance needed.
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Ray White



Joined: 02 Dec 2014
Posts: 3656
Location: Derby

PostPosted: Mon Feb 04, 2019 12:13 am    Post subject: More advance needed. Reply with quote

Here is one for the more experienced engine builders.

The car is my 1926 Dodge Brothers tourer. The engine is a 3.5 litre 4 cylinder side valve. The distributor shaft rotates clock wise which means the body is turned counter clockwise to advance.

The problem I have is that the timing would appear to be too far retarded. I say this simply because I have to fully advance the distributor to start the engine. Any attempt to retard causes rough running or a stall.

I have followed the workshop manual procedure for static timing but I believe it is not giving me enough spark advance. These engines have a "window"in the casting which shows flywheel markings. The workshop manual instructions are to turn the engine over on the handle until the compression stroke is felt with a thumb in the plug hole of No.1 cylinder. Continue to slowly turn the engine until the letter I is seen on the flywheel through the window. It should line up with a casting mark. This apparently sets the ignition timing at 12deg before TDC. Fit the distributor with the rotor pointing towards No.1 contact in the cap just as the points begin to open.

It all seems straight forward to me but the set up is clearly not giving me enough advance.

I thought perhaps I could move the distributor shaft clockwise by one tooth but that is easier said than done. Nothing is certain because I can't see what I am doing. Perhaps there is a way of working out the exact amount of advance at the flywheel to give the equivalent of one tooth at the distributor.?

Any suggestions?
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roverdriver



Joined: 18 Oct 2008
Posts: 1172
Location: 100 miles from Melbourne, Victoria, Australia

PostPosted: Mon Feb 04, 2019 9:21 am    Post subject: Reply with quote

One way to tackle the problem is to ascertain just where your distributor is in relation the the flywheel marks.

I would suggest using a pencil or thin dowel in No1 cylinder through the plug hole in order to find TDC after making sure that you are on the compression stroke. Gently moving the crankshaft back and forth, and feeling the piston 'rocking' will give a good indication of TDC. Now check if the flywheel is indicating TDC. If not, mark the flywheel at your known TDC and measure the difference between your mark and the official mark.

Now turn the flywheel to the 12 degree mark and using your measurement make a new 12 degree mark. Now set your dizzy to that mark.

I have done this when I have found that the camshaft gears have been misaligned but the cam to distributor is correct.
I hope that helps.
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Ray White



Joined: 02 Dec 2014
Posts: 3656
Location: Derby

PostPosted: Mon Feb 04, 2019 11:31 am    Post subject: Reply with quote

roverdriver wrote:
One way to tackle the problem is to ascertain just where your distributor is in relation the the flywheel marks.

I would suggest using a pencil or thin dowel in No1 cylinder through the plug hole in order to find TDC after making sure that you are on the compression stroke. Gently moving the crankshaft back and forth, and feeling the piston 'rocking' will give a good indication of TDC. Now check if the flywheel is indicating TDC. If not, mark the flywheel at your known TDC and measure the difference between your mark and the official mark.

Now turn the flywheel to the 12 degree mark and using your measurement make a new 12 degree mark. Now set your dizzy to that mark.

I have done this when I have found that the camshaft gears have been misaligned but the cam to distributor is correct.


I hope that helps.


Thanks. Unfortunately the plug holes are directly over the valves and so I can't test for TDC in that way. I can, however, see the valves from the side so maybe do it that way.

Cheers.
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47Jag



Joined: 26 Jun 2008
Posts: 1472
Location: Bothwell, Scotland

PostPosted: Mon Feb 04, 2019 7:06 pm    Post subject: Reply with quote

Ray,

Some thoughts. Is the distributor clamped to the advance lever or a fixed point? If clamped loosen the clamp and see if the distributor body can be moved again the direction of rotation (advancing)

Do you have a timing light? If so you should be able to illuminate the marks on the flywheel? Worth a try.

I used to use a technique on GM products called power timing when the vibration dampers rubber bond failed thus retarding the timing marks. You rev the engine to about 15-2000 rpm and advance the distributor until the revs start to drop, then back off a bit and clamp it there. Road test to see if the engine pings and adjust as necessary.

Art
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Ray White



Joined: 02 Dec 2014
Posts: 3656
Location: Derby

PostPosted: Mon Feb 04, 2019 8:02 pm    Post subject: Reply with quote

47Jag wrote:
Ray,

Some thoughts. Is the distributor clamped to the advance lever or a fixed point? If clamped loosen the clamp and see if the distributor body can be moved again the direction of rotation (advancing)

Do you have a timing light? If so you should be able to illuminate the marks on the flywheel? Worth a try.

I used to use a technique on GM products called power timing when the vibration dampers rubber bond failed thus retarding the timing marks. You rev the engine to about 15-2000 rpm and advance the distributor until the revs start to drop, then back off a bit and clamp it there. Road test to see if the engine pings and adjust as necessary.

Art


Hello Art. You say to "move the distributor body in the direction of rotation". If the rotor is rotating clockwise then moving the body of the distributor in the same direction will surely retard the spark??.
In this case the shaft and rotor are going clock wise so the body needs to be turned counter clockwise to advance the spark.

Unless I am mistaken.

The operating rod is clamped to a fixed position on the body and although it can be removed there is a peg at the back of the dist body that locates in a slot in the fixed casting which limits the amount of advance or retard available. I could elongate the slot but I try to avoid making permanent alterations if possible.

I have just come in from the garage where I have rotated the distributor by one tooth of it's spiral gear. The results are not promising but the battery has gone flat so until it is charged I can't do any more. Tomorrow I will check if the timing can be improved.
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colwyn500



Joined: 21 Oct 2012
Posts: 1741
Location: Nairn, Scotland

PostPosted: Mon Feb 04, 2019 10:27 pm    Post subject: Reply with quote

I'm not clear about whether you are able to be sure exactly where TDC is on No.1 cylinder or if that's actually the dilemma. But if you can be sure, then when it's at that point you could make Tippex mark anywhere on the front crankshaft pulley. Then make an aligning one on the timing-chain cover. Measure the pulley diameter in mm. and use schoolboy maths to get the circumference in mm. Divide this number by 360 and then you have the number of millimetres or fractions thereof that make 1 degree. Multiply by your 12 degrees of static advance and using that figure, measure clockwise around the pulley edge from the first mark and make a new mark. (Obviously I don't know your engine but I'm presuming the pulley turns clockwise looking from the front).
You now have a reliable static advance mark which you can use with a strobe-light. Or you can keep turning the engine to align the new mark and the one on the chain-cover and set the points to be just opening when the rotor-arm faces No. 1 by rotating the distributor anti-clockwise. You should only need to remove the distributor if it isn't possible to achieve this within the mid-range of movement of the distributor.
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47Jag



Joined: 26 Jun 2008
Posts: 1472
Location: Bothwell, Scotland

PostPosted: Mon Feb 04, 2019 11:19 pm    Post subject: Reply with quote

Ray,

You are correct, against the rotation.

Iím having problems with my iPad since junior grandboys dropped it and cracked the screen. I probably typed it in correctly but it seems to be losing characters and complete words. My apologies.

You have moved it a tooth so you should see some difference. I would still try the timing light (assuming you have one)

Art
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Rick
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Joined: 27 Apr 2005
Posts: 21314
Location: North-west UK

PostPosted: Mon Feb 04, 2019 11:31 pm    Post subject: Reply with quote

Is your dizzy driven by a gear-driven shaft from the front of the engine, that passes through the water pump en route to the dizzy? Could it be a tooth out at that forward end? I'd have to re-read my notes & photos for when I removed the water pump from my (mag) engine, but I do recall it being critical to replace the ensemble exactly as it came off to preserve the timing.

RJ
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Ray White



Joined: 02 Dec 2014
Posts: 3656
Location: Derby

PostPosted: Mon Feb 04, 2019 11:58 pm    Post subject: Reply with quote

Rick wrote:
Is your dizzy driven by a gear-driven shaft from the front of the engine, that passes through the water pump en route to the dizzy? Could it be a tooth out at that forward end? I'd have to re-read my notes & photos for when I removed the water pump from my (mag) engine, but I do recall it being critical to replace the ensemble exactly as it came off to preserve the timing.

RJ


Yes, the drive is taken from a gear on the water pump shaft but I don't think it would be possible to assemble it incorrectly because the gears are all keyed. With this "C" engine you set up the timing using the window to align the mark "I" on the flywheel on the compression stroke. It should then be a simple matter of ensuring the rotor is pointing at No.1 contact in the cap and the points just opening.

I have been out to the garage again and with the battery charged I have attempted two start the engine with the distributor moved clockwise by just one tooth. It refuses to start. I think there is now too much Advance!!!
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Ray White



Joined: 02 Dec 2014
Posts: 3656
Location: Derby

PostPosted: Tue Feb 05, 2019 12:02 am    Post subject: Reply with quote

47Jag wrote:
Ray,

You are correct, against the rotation.

Iím having problems with my iPad since junior grandboys dropped it and cracked the screen. I probably typed it in correctly but it seems to be losing characters and complete words. My apologies.

You have moved it a tooth so you should see some difference. I would still try the timing light (assuming you have one)

Art


I need a modern timing light which shows the degrees of advance in a display (other wise I am still in the dark, so to speak) Laughing

I am still faced with the problem of having either not enough or too much advance and no means of adjusting to a mid way setting.
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47Jag



Joined: 26 Jun 2008
Posts: 1472
Location: Bothwell, Scotland

PostPosted: Tue Feb 05, 2019 1:34 pm    Post subject: Reply with quote

Ray,

The timing light you mentioned is really only useful for checking automatic advance mechanisms.

I understood your problem to be finding the marks on the flywheel to use as a static reference point from where you would then advance manually.

That timing light would be useful 'after the fact' when you have done your road testing and found the optimal timing. These light allow you to 'dial back' and read how many degrees you have advanced. Your choice.

Art
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Ray White



Joined: 02 Dec 2014
Posts: 3656
Location: Derby

PostPosted: Tue Feb 05, 2019 3:27 pm    Post subject: Reply with quote

"I fixed the car, honey " Laughing

I can't believe it. For some reason I had missed a clamping screw tucked up under the distributor.

Anyway, I can now start the car with the ignition retarded and have plenty of advance as and when required.

Many thanks to everyone for their helpful responses.

Very sorry for my stupidity. Embarassed Embarassed Embarassed Embarassed
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MVPeters



Joined: 28 Aug 2008
Posts: 718
Location: Northern MA, USA

PostPosted: Tue Feb 05, 2019 8:03 pm    Post subject: Reply with quote

Our pleasure, Ray!

Very Happy
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Steve00136



Joined: 14 Jan 2019
Posts: 23
Location: nottingham

PostPosted: Sat Apr 20, 2019 7:59 am    Post subject: Reply with quote

Try setting timing using vac gauge - this is how i did mine at https://mymgbinfo.wordpress.com/2019/04/10/vacuum-tester-ignition-timing/
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alanb



Joined: 10 Sep 2012
Posts: 491
Location: Berkshire.

PostPosted: Sat Apr 20, 2019 8:23 pm    Post subject: Reply with quote

Setting the timing to manufactures settings is ok as a starting point but just remember fuel when our cars were built was 70 octane or less, modern fuel is 90+ octane so timing may need to be adjusted to compensate for modern fuels.
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