[jonnyc]

Hi all, hope this finds everyone healthy and Happy New Year all.
So I went out in the garage, set the rpm's to 1200 tried to read the timing, that was a joke, cleaned the heck out of the crank shaft damper and finally was able to see the marks, my vision! Could have used binoculars. At 1200 rpm it seemed to be reading like 22 but at 650 rpm it was reading around 10 and the workshop manual says, I believe between 7-13 at 650, raise the idle and it seems nice and smooth. Checked vacuum lines and egr, all seems well. I'm reluctant to mess with the distributor to play with timing. I've been testing everything to avoid changing the HT leads, seems like it wouldn't be fun, I do now plan to change them and see what happens, its extremely possible they are original. Any wisdom/comments from anyone is welcome. Let me say that when I say lumpy I'm meaning that there is an occasional lump, I dont mean to imply running rough by any means but I know it can be more smooth and I have posted about this in the past, but revisiting this now that since covid I seem to have a bit more garage time. And a side note the section U of the workshop manual is over 500 pages, I never new there were so many possible variations.

Cheers!
Jon

 

[Wraithman]

You can also have a small vacuum leak at the cruise control bellows. You can cap it off and check results. On my 1980 SWII I installed a Pertronix ignitor pick up and the idle is much smoother now.
I plan the same on my 1976 and 1980 Shadow II.
Your wires should be replaced at this point.

 

[Dounraey]

When you change the HT leads, measure the outside diameter and make sure the replacement wires are the same, else you will have difficulty threading them through the support tube assemblies. HT leads are typically 7mm, 8mm or 10mm. I believe the Shadow HT leads are 7mm, but may be wrong hence my note to measure them.

I have dispensed with the support tube assemblies on my car and run the wires across the engine, held by clips. The reason is I figured bending modern wires through sharp 90 degree angles, as required with the support tubes, might break the carbon trace and also I like the wires visible for easier fault finding.

I have kept the support tube assemblies in case I want to revert to original in the future, but I find it so much easier to have the wires over the engine in the conventional way.

 

[jonnyc]

So let me be sure I understand, I should take the vacuum line off the cruise bellows and just plug it and see what happens, can I have more info on the Petronix?
never considered wires over the engine, hmm, I do like the tidy look of the support tubes but they sure do obscure things, by design I think, Never considered the fact that bending a wire to 90 degrees could damage it. I was planning on buying the wires from Flying Spares with the rubber wire guides already installed to save some work, I'm sure they would supply the correct diameter? Or does anyone know of another source for proper wires, I really like the idea of having the guides pre installed but idk.

 

[Wraithman]

You will not hurt anything by bending the wires. If you cut one open you will see why. Everything is quite flexible. I use the wires from FS and they are excellent.

 

[jonnyc]

FS it is then! I'm hoping the wires will help or maybe solve the problem. I already did the cap and rotor (which I posted in the past) and no huge difference, plugs too. Wires are the last piece of that puzzle, once done I can rule those pieces out if the problem persists.

 

[shadow 11]

Have you checked the distributor dwell angle is within spec and that the dwell is not fluctuating which would possibly indicate a worn distributor shaft bearing or bad rotor arm. There are dodgy rotor arms on the market.

 

[jonnyc]

I haven't checked dwell, I believe my meter can do that, not sure I know how...but I'll learn👍😁

 

[jonnyc]

Thinking...doesn't dwell have to do with points? My car is electronic. Someone share some wisdom on this please and thank you

 

[Hornets7]

Thinking...doesn't dwell have to do with points? My car is electronic. Someone share some wisdom on this please and thank you

Thinking...doesn't dwell have to do with points? My car is electronic. Someone share some wisdom on this please and thank you

Hi

Thinking...doesn't dwell have to do with points? My car is electronic. Someone share some wisdom on this please and thank you

On my 1980 SS2, I had a similar problem with lumpy at tickover. It turned out to be one carburettor running very lean. I had them balanced and the mixture set correctly, now runs like a dream.

SRH 40736

 

[Jeff R 1]

Thinking...doesn't dwell have to do with points? My car is electronic. Someone share some wisdom on this please and thank you

Yes, dwell is how long the points stay closed, measured in degrees out of 360 of course.
The longer the points stay closed, the more current flows into the coil _ the more saturated the coil becomes with voltage _ and the stronger the spark you get, when the points open _ when the points open the magnetic field collapse inducing a very high voltage into the secondary windings producing the ignition spark.

All this applies to electronic ignition as well, but it's non adjustable.
You can only adjust for advance and retard, but that would not cause a lumpy idle.
Leave the distributor alone, change you wires if they are original.
Do one wire at a time so you don't get the firing order mixed up.

As mentioned earlier, change your spark plug leads if they haven't been changed for a while.
Also make sure that the pistons in your dash pots move freely, your mixture is correct and the carbs are balanced.
If any of these things are not set right, then the car will idle poorly.

 

[shadow 11]

Measuring the dwell will help to confirm if there's any play in the distributor shaft or rotor arm. Dwell reading should be steady if there's no play.

 

[jonnyc]

Hi All,
first thanks for all the replies, so i bought the gauges from Kelly a while back and balanced the carbs, the mixture adjustment, however, I've never touched. The carbs were rebuilt a few years ago, I know that the caps on the mixture screws are not there which tells me at some point someone made adjustments there. How do you adjust the mixture? is it just a case of turn it one way or the other and see what happens or is there a method?

 

[Wraithman]

I'm sure it is here: http://rrtechnical.info/SY/TSD4200/tsd4200_k.html

 

[shadow 11]

I have HIF7 cards but I've never messed with the mixture screws. I read somewhere that a CO2 exhaust gas analyser is needed to measue the correct air/fuel mixture. The colour of spark plug deposits are usually a good indication of whether it's running rich, lean or just right. You could also remove the carb top covers and compare the height of each jet in relation to the bridge.

 

[jonnyc]

Hi All,

More questions... I just ordered the new wires (HT Leads) from FS, I will await their arrival, meanwhile, to properly change the wires and run them through the metal channels which is what I want to do, do you have to take the "antlers" off in order to remove the channels? seems like you have to take quite a bit apart to get to those wires. Am I on the right track here? And if so is there something I need to know before removing the antlers? should I remove them and blank off the holes and forget the whole arrangement? Something as "simple" as wires seems to be opening up a much bigger project here.

 

[Dounraey]

Hi Jonny

When you say you've ordered the new wires, do you mean all 8 or just the ones you suspect are faulty?

You will not have to take the antlers off to remove the channels. Each channel is held in place by two bolts and the wires can be easily removed or inserted through the slot that runs the length of the channel. The first pic below will help make this clear.

I don't know if you can push the individual wires through the antlers. My guess is if you remove the spacer at the round end you should be able to, but I don't know if this is possible in practice. It will be interesting to hear other owners views on this.

I include the second pic in case you decide to remove the antlers. Each is held in place by a single bolt which goes through the hole in the bracket. The problem is it is very fiddly to remove these bolts as they are located between the engine and the bulkhead and access is difficult. Definitely doable though. As I recall they are 1/2" or 7/16".

I should point out that my car is a 74 SY1 (SRX18501), but I believe the series 2 are similar.

 

[Dounraey]

RE: should I remove them and blank off the holes and forget the whole arrangement?

Yes!!!

I'm only joking. I have done so but the down side is you lose originality. If I ever decide to sell my car I will refit the antlers and channels.

 

[jonnyc]

Dounraey,
When I say antlers I am referring to the Egr piping, your second picture shows the HT lead sleeves. So now I'm a bit confused. What else is new😁

 

[Wraithman]

The "antlers" are the formed tube manifolds that deliver air from the smog pump to the exhaust side of the head.
Kelly @ BTW has a blank off kit. Remove the drive belt as well and check valves. Take plenty of pics and print them.
I'm fortunate my '80 SWII-FI has no smog pump or the plumbing. The '76 is a jungle and the '80 SSII-carb is not as crowdwd but has the smog plumbing.

The tube for the wire leads is often referred to as "conduit"