Ignition timing - low idle?

[river_thames]

Hello there,

Last year, I inherited the family Herald 1200. It's on the road, and just about running, though it was services last year.

I need to start learning, and don't have any contacts or clubs near me. You can expect a lot of novice questions I'm afraid. But at least I'll be able to contribute one day.

First order of the day would be timing I think. Over the past few months, the idle has dropped, revs are quite low and it can stall pretty easily. I'm led to believe that this could be ignition timing. I understand some basic principles but finding a straightforward guide has been hard. For example, finding the correct degrees from TDC?

Can anyone point me in a good direction, for either adjusting my timing or my low idle? Thank you!

[Pete Lewis]

first put a reprint workshop manual on your wish list  club shop and others sell them

you  can read Steves online http://vitessesteve.co.uk/Servicemanuals

to use the factory setting you really need to use 97+ fuel not 95 

with no checking lamps strobes or whatever , undo the clamp on the distributor ,,with it idleing rotate the dizzy body  one way will speed up the oposite it will slow down

turn to get the best idle speed and reduce it to less than best , if the idle speed is still on the slow side use a screwdriver to turn the carb  idle stop screw in 

once you have reasonable idle and  you can drive her , accelerate in 4th at 40 mph  does it make any tin rattle 'pinking ' noises if so reduce the dizzy back till that stops .

lots of other things affect poor idle  dizzy points gap, tappets , carburettor  settings 

you will have a mixture volume screw on the base of the carb, screw in weakens screw out richens   this only controls the idle mixtute not the main running 

try it you will soon get a feel for the changes you are playing with   

Pete

[river_thames]

Hi Pete thank you so much. Now the weekend is here I’ll have a go. I’ll get a manual too. Where would be a good place to learn how to adjust timing when it comes to replacing my points? The set I have are new.

[Anglefire]

Try YouTube. It pretty much is my goto these days as there is not much that hasn’t been video! 

[dougbgt6]

RT,

I survived with a Haynes manual when I knew very little. They are very good, Loads on Ebay, £20 new, less than £10 2nd hand. The work shop manual is nice to have, but expensive! Also have a look on the "Areas" section on the front of this site, M25 East might be near you? No areas meeting at the moment, but that won't last forever!

Doug

[SpitFire6]

Hi,
 talking about the downloadable WSM; Are the recommended lubricants viscosity ratings correct? 
I also noticed SAE20 for the SU dash cap. I guess you buy it from SU.

Cheers,

Iain.

[dave.vitesse]

8 minutes ago, SpitFire6 said:

Hi,
 talking about the downloadable WSM; Are the recommended lubricants viscosity ratings correct? 
I also noticed SAE20 for the SU dash cap. I guess you buy it from SU.

Cheers,

Iain.

SU oil is available from Burlen Ltd 01722 412500

Dave

[Pete Lewis]

so whats the specific values of using a straight sae 20  to using a sae 20/50 

pete

[Anglefire]

It’s the grade that SU recommend - but 20/50 is what triumph recommended. 
take your pick. 
I actually bought some 20Sae chain oil and use it in mine. But when it runs out I shall just use engine oil.  

[SpitFire6]

SAE20 is much thinner than 20W50 across the range.

Triumph recommended SAE 20. It is in the manual for the Heralds. Spitfires

Edited April 18, 2020 by SpitFire6
edit Nick Jones Post Below.

[johny]

I think both oils are the same thickness at one temperature but then the multi grade will not thin nearly as much as the temperature goes up. Can't remember the temperatures used for testing but it's probable that at the relatively low temperature in a carb their consistency will be similar.

[SpitFire6]

Average 20W50 is around twice as "thick" as SAE20 at 100c. Three times as thick at 40c.

 

[Anglefire]

But in a carb the temperature change is not significant- compared to inside an engine. So the thickness at the operating temperature in would have expected to be similar?  

[Nick Jones]

1200 doesn’t have an SU, so dashpot oil not relevant.

First thing to check is points gap. Points currently available are made with soft plastic so the the heel wears quickly, closing up the gap, which also retards the timing. Simply resetting the gap usually points the timing back close to where it should be.

Doubt a 1200 cares much about 95 or 97 fuel with 8:1 compression.

Nick

[johny]

4 hours ago, SpitFire6 said:

Average 20W50 is around twice as "thick" as SAE20 at 100c. Three times as thick at 40c.

 

That can't be right otherwise we'd really have problems using engine oil in our dashpots. A 20w50 tests like a straight 20 oil in the winter(w) test so as the temperature it's used at goes down the more similar they become in terms of viscosity.

[SpitFire6]

22 minutes ago, johny said:

That can't be right otherwise we'd really have problems using engine oil in our dashpots. A 20w50 tests like a straight 20 oil in the winter(w) test so as the temperature it's used at goes down the more similar they become in terms of viscosity.

Here is one comparison.

[Colin Lindsay]

14 hours ago, Nick Jones said:

1200 doesn’t have an SU, so dashpot oil not relevant.

 

I had to read back over all the posts to make sure it wasn't a twin-carb with HS2s fitted, but that's not mentioned. Assuming it's standard Solex then as Pete says the idle adjust screw is on the base of the carb.

Rotating the distributor clockwise will advance the timing; best to mark the position it's currently in, white paint or Tippex, just a dab on the block and distributor body so you'll have a reference point and you'll know how much you've adjusted it compared to where you started. It's only a very small amount in any case. Starting point is 15 degrees BTDC and it's a case of dynamic tuning after that, trial on the road and adjusting as the car performs.

[johny]

14 hours ago, SpitFire6 said:

Here is one comparison.

hmmm Ive had a look at this and its an interesting and complicated subject. Turns out SAE20 and SAE20w oil isnt necessarily the same thing as the first is an oil that meets a certain test at high temperatures and the second meets a different type of 'winter' test at very low temperatures. So a 20w50 oil is one that would pass the same low temperature test but also comply with the high temperature test of an SAE50 oil. I guess the only conclusive answer for our purposes would be to compare the viscosity of SAE20 and 20w50 at say 40 degC by measuring the time the same quantity of each takes to flow through a fixed size hole which wouldnt be difficult to do....

[SpitFire6]

Hi,

 Going to begin a new Work Shop Manual  SAE20 oil to a new thread @ Technical Engine.

Cheers,

Iain.

[Pete Lewis]

1 hour ago, johny said:

measuring the time the same quantity of each takes to flow through a fixed size hole which wouldnt be difficult to do....

i get the same trouble  with or without the pills   

Pete