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David Lacey
New User
Username: dlacey

Post Number: 2
Registered: 11-2010
Posted on Tuesday, 04 September, 2012 - 06:17 pm:   Edit PostDelete PostView Post/Check IP

All,

I have a '68 Shadow SRH4452, with dual-point style distributor in good condition. Vacuum advance is working and mechanical advance weights move freely. I inadvertantly moved the distributor when extracting the heater matrix, so need to reset the timing...otherwise the car was running just fine at only 45Kmiles...

Ignition timing should be 4-5 Degrees BTDC on 100 Octane fuel, I am running 95 octane but don't think that's my problem root-cause. I'm using the timing marks on the front pulley and have double-checked them against the flywheel marks & all is good.

I'm timing dynamically at idle using a strobe triggered from A1, the right front cylinder (as viewed from driving pos).

Problem: The car hardly runs at 5 degrees BTDC, in fact it only runs at something more like 20 degrees BTDC, even then missing a lot under acceleration.

How can this be? am I timing on the wrong cylinder? I have read the electrical section of the manual many times but have no breakthrough...
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Hubert Kelly
Experienced User
Username: h_kelly

Post Number: 25
Registered: 3-2012
Posted on Tuesday, 04 September, 2012 - 08:13 pm:   Edit PostDelete PostView Post/Check IP

Hi David, I to have a '68 Shadow SR42145. I am glad to see your car with such low miles.. mine has approx 66k miles on the clock. I thought it had been round the clock several times, though it is believed to have been a one family owner for most of its life(you give me hope it might be genuine miles). I am of no help to you with your query.
I replaced the hub caps recently(to vented caps) as I found the brakes/hub/tires extremely hot, following constant braking on twisty country roads. thankfully the vented caps solve the problem. Have you ever noticed a similar situation ?
Hk
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David Lacey
New User
Username: dlacey

Post Number: 3
Registered: 11-2010
Posted on Wednesday, 05 September, 2012 - 01:01 am:   Edit PostDelete PostView Post/Check IP

Hi Hubert,

Thanks for your message, i do hope yours is 066 rather than 166 or 266 ! I am lucky to have car in such an unspoilt state, however I needed to add airconditioning as this is a basic human right in Malaysia.... hence disturbing the heater.

Do you think the vented hubcaps make such a big difference? I guess they changed that for a reason, but still such a car must have undergone extensive testing at launch and so an issue like poor brake cooling should have been solved?? Or maybe people just drove/braked harder in the 70's!!
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Hubert Kelly
Experienced User
Username: h_kelly

Post Number: 26
Registered: 3-2012
Posted on Wednesday, 05 September, 2012 - 02:28 am:   Edit PostDelete PostView Post/Check IP

Hi David, im sure adding A/C is a big job. I have been to your country, to the island of Langkawi, fabulous place. In relation to the vented hubcaps, I feel more comfortable with them to be honest as , I really thought I had trouble on my hands when I saw the steam/smoke rise from the wheels. Following that experience I stick to the main roads/motorways. Can't thank this site enough, without it, I would have sold the Shadow, a long time ago.
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David Lacey
New User
Username: dlacey

Post Number: 4
Registered: 11-2010
Posted on Wednesday, 05 September, 2012 - 08:40 am:   Edit PostDelete PostView Post/Check IP

Hi All,

Any thoughts/hints/ideas on my ignition timing problem??

david
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Dave Puttock
Experienced User
Username: ariel

Post Number: 33
Registered: 5-2010
Posted on Wednesday, 05 September, 2012 - 09:42 pm:   Edit PostDelete PostView Post/Check IP

Are you strobing the ignition with the vacuum advance disconnected. I think the figures refer to the fully retarded state at tickover.
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David Lacey
New User
Username: dlacey

Post Number: 5
Registered: 11-2010
Posted on Wednesday, 05 September, 2012 - 10:53 pm:   Edit PostDelete PostView Post/Check IP

Hi Dave,

I've tried with & without vac advance connected, it appears to make no difference. The manual makes no reference to disconnecting the vac advance on these early chassis Nos, for the later cars it does state to disconnect.

Thanks for the input, I'll triple-check but i dont think this is it..

david
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Hubert Kelly
Experienced User
Username: h_kelly

Post Number: 27
Registered: 3-2012
Posted on Thursday, 06 September, 2012 - 02:49 am:   Edit PostDelete PostView Post/Check IP

HI David having read your post, is it true to say you reckon your problem is timing related, having moved the distributor. My '68 Shadow missed a lot when I first got her, I replaced distributor cap, rotor arm, new leads, coil, plugs and a ballast resistor, she now runs perfectly. I know your symptoms are somewhat different. Did you by any chance move the ballast resistor wires?. The other thing to keep in mind is the condition of the leads, as you are probably aware the twist leads into the distributor cap are delicate to say the least. This may be of absolute no use but if all else fails it might be worth checking the condition of items mentioned.
hk
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David Lacey
New User
Username: dlacey

Post Number: 6
Registered: 11-2010
Posted on Thursday, 06 September, 2012 - 05:29 pm:   Edit PostDelete PostView Post/Check IP

Hi Hubert,

There's no Ballast Resistor on a '68 is there?? According to the wiring diagram I can't see one, only cars >5001 had one?? Agree that dodgy ignition components could be an issue, but i still don't understand why the car drives OK with ignition at an (indicated) ~20 BTDC when it should be 3-5 BTDC ...
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Hubert Kelly
Experienced User
Username: h_kelly

Post Number: 29
Registered: 3-2012
Posted on Thursday, 06 September, 2012 - 07:09 pm:   Edit PostDelete PostView Post/Check IP

Hi David, I can't speak of the wiring diagram, as per my logbook SR42145 engine number SY 2145 registered 01- December 1968 Australian import, whether original or aftermarket I can't say(my car definitely has a ballast resistor) . I just checked out Flying spares web where I purchased those items, from what I read the ballast resistor is present in cars from 1966-1975 (vin 1942-22117) David please don't take this as gospel, its something someone else might through light on. I have read from the site that the ballast resistor if, not functioning correctly can give a lot of "ignition" problems". Hope this was of help.
HK
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Carl Heydon
Experienced User
Username: car

Post Number: 32
Registered: 2-2004
Posted on Friday, 07 September, 2012 - 07:40 am:   Edit PostDelete PostView Post/Check IP

I believe the answer to your problem is that the timing mark is on the rubber mounted harmonic balancer not the fixed pulleys. Ignore it (though you should replace it, especially if you can see it wobbling).
Advance the timing till it 'pings' under load then retard it a bit. It doesn't get any better than that. The ideal advance changes with every change of fuel and altitude. After practice you can rotate the distributor and hear/feel when it is sweet.
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David Lacey
New User
Username: dlacey

Post Number: 7
Registered: 11-2010
Posted on Friday, 07 September, 2012 - 12:50 pm:   Edit PostDelete PostView Post/Check IP

Hi Carl,

Yes, I am reaching the same conclusion...that the best way is the 'experimental method'. I use this on a 4-cyl Triumph TR4a for many years, so I should try it here also & not worry about the markings (except, as you suggest, the harmonic balancer may be disintegrating).
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David Lacey
New User
Username: dlacey

Post Number: 8
Registered: 11-2010
Posted on Monday, 08 October, 2012 - 05:06 pm:   Edit PostDelete PostView Post/Check IP


All,
Well I have completed my trial-n-error setting of ignition timing, firstly by twisting the dizzy around by hand & later using the fine adjustment. It's now smooth under all conditions and has a very slight pinking under load for a second (95 octane in a 100 octane engine).

I get out the timing light and it confirms that it's somehow way-off the markings...looks to me like ~40degrees BTDC... I will try to check the flywheel timing marks when I get the car elevated in November... but so far it runs good even if the owner is confused...
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David Gore
Moderator
Username: david_gore

Post Number: 1144
Registered: 4-2003
Posted on Monday, 08 October, 2012 - 06:47 pm:   Edit PostDelete PostView Post/Check IP

David, I suspect the distrbutor has been removed at some stage and the engine crankshaft accidently/deliberately moved and not realigned before the distributor was replaced.

Another possibility is the distributor drive gear was not correctly aligned when the distributor was replaced and the resulting rotor misalignment was corrected by repositioning the plug leads on the distributor cap. The next person to replace the leads does it "by the book" and finds the car no longer runs properly and then goes through your experience trying to fix the problem.
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Paul Yorke
Grand Master
Username: paul_yorke

Post Number: 869
Registered: 6-2006
Posted on Monday, 08 October, 2012 - 07:27 pm:   Edit PostDelete PostView Post/Check IP

My thoughts earlier David G, But with a strobe timing light on plug lead A1, the timing light should still fire in the right place regardless of distributor placement.(must still fire in the right place to run properly).

Pistons, valves & spark must align. Maybe the pulley or pointer is wrong? David L Have you checked the Pulley and Pulley TDC against the flywheel TDC?

Have you tried the strobe on the flywheel?

Have you tried another strobe light?
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gordon le feuvre
New User
Username: triumph

Post Number: 3
Registered: 7-2012
Posted on Tuesday, 09 October, 2012 - 05:52 am:   Edit PostDelete PostView Post/Check IP

Does your strobe have facility to dial in degrees? If so, this needs to be set at 0 degrees, otherwise you are in fact doubling up when aligning 5 degrees. The strobe should be set to 0 degrees and then you can line pointer on 5 degree mark on crank.Idle should be as low as poss. with vacuum disconnected.
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David Lacey
New User
Username: dlacey

Post Number: 9
Registered: 11-2010
Posted on Tuesday, 09 October, 2012 - 11:44 am:   Edit PostDelete PostView Post/Check IP

Hi David/Paul/Gordon,

I agree with you - it runs well, so that means that Pistons/Valves/Sparks are all synchronised as they should be... the only bit of 'data' that is proven wrong is the front pulley timing marks/pointer using a simple strobe light triggered off A1... I did check the Pulley Marks against the flywheel marks before and convinced myself that they were aligned, I must now double-check this and try the strobe on the flywheel marks.

The easiest explanation is that the front pulley is misaligned because the outer ring of the vibration damper has delaminated/failed.
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Billy H
Unregistered guest
Posted From: 86.4.27.43
Posted on Wednesday, 19 December, 2012 - 01:16 pm:   Edit PostDelete PostView Post/Check IP

(Carl Heydon)"Advance the timing till it 'pings' under load then retard it a bit. It doesn't get any better than that." Couldn't resist a comment; AGREE entirely. This takes care of any 'slack' in distributor and any other related gear etc. No need for timing lights, test lamps etc. Just so long as all cables/wires and components mare generally serviceable. (Maybe keep a dizzy spanner in the boot.)

(Message approved by david_gore)
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David Lacey
Experienced User
Username: dlacey

Post Number: 20
Registered: 11-2010
Posted on Tuesday, 10 June, 2014 - 06:56 pm:   Edit PostDelete PostView Post/Check IP

All,
Some follow-up on this:
I believe the root-cause is stretched advance springs on the centrifugal advance, the springs provide no resistance to the movement of the weights for a good 10 crank degrees, maybe more...the weights just 'flop about'...hence the inability to set the timing for proper running. I am getting the dizzy rebuilt by Martin Jay in UK...hopefully will have a positive outcome in August.

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