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smyllie

123 ignition timing woes

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Well after a 6 year full restoration i have taken my 63 TR 4 out on the public road for the very first time. I also decided to take it for a voluntary MOT for my own piece of mind. Overall the driving experience was good, however I am struggling with the ignition timing. This is my first such project and I am not experienced in the art of interpreting the engines performance and determining how to alter the timing. The engine has been fully rebuilt with an unleaded head conversion - everything is to standard specification. I have a 123 ignition which is set to map B. The static timing is set to 10 BTDC. When in neutral or with no load the engine starts perfectly and revs cleanly when the accelerator is pressed. However out on the road when accelerating it sounds dreadful almost as if its running on 3 cylinders and really struggles to make progress. At cruise it seems much happier. Yesterday I took it up a hill and it is pinking. I have also noticed a whistle from the carb (rebuilt CD175s) area but still yet to pinpoint the source.

I have read the previous posts on intial setup with the 123 and have seen many different views on static setting and which curve to use. Does anyone have any comment on my current 10 BTDC and curve B. Any ideas on the rough running under load. I am leaning towards something related to the vacuum advance but would like to sound out you wiser readers before diving in.

 

20190507_163418.jpg

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Hi,

Important you know that the curve you have selected is right for your cam and compression ratio and that vacuum advance is needed with this distributor. Pinking (the metallic clicking sound when engine is working hard) is destructive, if nothing else, retard the static setting until it stops.

Mike

 

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Hi Smyllie, - I have also recently fitted same 123 ignition system with same carb set-up and also been driven to distraction with the seemingly endless options.

 

However, with some hard learned hindsight, I think I may have been getting too carried away with the ignition; I’m back to setting it up best as poss static, I wasted so much time to finally find that one of the carbs was (suddenly?) now not lifting smoothly .. Suggest taking the filters off and monitoring, I had to loosen the four screws off, clean up and re-‘torque’ them evenly - all very frustrating.

Agree, also checked the vacuum but, for me, most of the woes actually were the carb

 

Keep us updated and good luck

Tony

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Fully agree with Mike, - crude but effective I advanced until pinking and then retarded accordingly, then a bit of tippex

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I thought the static timing for the TR4 was 4' BTDC - may be wrong !!

Retard it anyway and then advance it slowly to see when pinking begin.

Drive the car at 30mph in 4th and hit the throttle. Advance the ignition until it starts to pink - may involve a number of goes at this.

Minor adjustment to spark timing can be done of the dizzy.

 

Roger

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Got any oil in the carb dash pot dampers?  

Cheers

Peter W

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You are right Roger, that’s the ‘factory setting’ and oil in the dash pot dampers (hopefully) a given for newly rebuilt carbs Peter? - I (must have) disturbed something in my front carb when I replaced the diaphragm, even with oil in the motion was jerky..

Sure this is not ‘by the book’ or for the purists but you can also narrow it down, away from ignition towards carb(s) by spraying a judicious amount of easy start / carb cleaner directly into misfiring engine

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Thanks for the super quick responses gents. So on my list is check dashpots, check both carbs are sliding freely, retard ignition until it stops pinking.

Is there a neat trick to checking that the vacuum pipe is sucking? and finally do you have any thoughts on which curve to use for safety.

Cheers Bob

 

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Nice car, congratulations.

It could well be that your engine is running lean. 

Waldi

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13 hours ago, Waldi said:

Nice car, congratulations.

It could well be that your engine is running lean. 

Waldi

Thank you Waldi

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Hello Smyllie

Your car is a nice colour - what colour green is it?

Also on question of pinking don't rule out petrol. Last year a couple of us filled up at a supermarket petrol station and both cars run terribly afterwards. No power, popping and hesitating. Fresh petrol made all the difference.

I have standard points system and pinking usually due to dwell angle (points gap) wrong. My static timing from memory is approx 4 deg btdc. 

Stromberg pistons should lift up and down on lifting pins easily (remove dashpot filler caps to check this). If they don't then needle misaligned with jets. Also there seem to be some thicker rubber diaphragms on sale. Get the ones from Burlen  - they seem to be better. 

If you have the standard vacuum advance then attach a piece of pipe to the disc shaped vacuum advance unit and suck. If the diaphragm inside is ok then you will feel resistance. If you don't then the innards are shot and you need a new one. You should also see the vacuum advance mechanism move inside the distributor when you suck on the pipe. Re whistling from carb area check the end of the vacuum advance pipe is secure at the carbs end and not a loose fit.

Also make sure both carbs levers move together. If not loosen one of the 'curly' connectors and adjust so both sets of carbs rods move exactly together. Sometimes the one at the front will start to move before the one at the rear so take up any slack.

Problem is you can spend ages trying to sort out these things because it seems to be never a case of only one fault.

Good luck - let us know how you solve it.

Keith

 

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Lovely photo, will be just like mine when I finish it.

Same colour as mine I reckon, Triumph Racing Green, also known as Conifer green.

 

Edited by RobG

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The 'whistle from the carbs' is likely to be an air leak - that needs fixing first. I found a pinhole in my inlet manifold, easily fixed with a blob of silicone gasket compound.

Pete

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What makes you think it's ignition? 

Sounds like a carb mixture issue, too weak... When it's missing does it improve if you momentarily pull the choke a long way?? If yes it proves weak mixture.

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Have you by any chance fitted a heat shield bolted between the carbs and manifold.............they can leak for a pastime and cause no end of problems, running lean , pinking and running on.

Saw a car with this problem at a well respected fettling establishment yesterday. Shield removed problem solved, another upgrade which possibly wasn’t.

Iain

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Hi All, thanks for the additional advice. I have not had a lot of garage time over the last couple of weeks. Thanks for the compliments on the car, yes the colour is conifer green which was the original colour. After such a long project it is nice to get some feedback, thank you.

I think you are right and the timing is a red herring. I checked the dashpots and both were slightly low, so topped up and no improvement. I  then investigated the whistle which was coming from the inlet on the front carb. I removed the air filters and it is quite pronounced. So I switched the air valve/diaphragmm assembly between the two carbs and the whistle moved to the rear carb. So I am guessing that it can only be the diaphragm, the seal around the vacuum chamber or the attachment to the air valve. The diaphragm was new with a rebuild kit but I have ordered a new one anyway. I cannot think of any other potential source of the whistle but any alternative suggestions gratefully received. Whilst looking at the air valve assemblies and needle/jet alignment i noticed a very odd thing that I feel sure is not helping. The needles came with the car which had been sitting in a field since 1978. I was examining them and noticed that someone in the past has filed away one edge along the entire length of both needles. So if I cut one in half and look at the cross section it would be 'D' shaped. This was obviously intentional at the time as both needles have been modified (roughly the same) and on the same side. 

I have ordered two new standard needles and will let you know how i get on. Has anyone seen or heard of this before?

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On 5/15/2019 at 8:26 PM, iain said:

Have you by any chance fitted a heat shield bolted between the carbs and manifold.............they can leak for a pastime and cause no end of problems, running lean , pinking and running on.

Saw a car with this problem at a well respected fettling establishment yesterday. Shield removed problem solved, another upgrade which possibly wasn’t.

Iain

Hi Ian, I have not fitted a heat shield, I decided to ceramic coat the exhaust manifold to help. Pricey but work really well. 

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Hi, sorry it has been a while since I have had time o update the forum. Those of you who suggested that timing may not be the cause were correct. Ultimately it was a sticky air valve/piston on the front stromberg carb. Before rebuilding the carbs I had them vapour blasted. Apparently this process can create a rough surface and in fact caused the valve/piston to stick on load. Removed both air valves, lightly polished both with fine wet and dry and the car runs nicely. Thanks for your help. Now off to fit the hood frame, webbing and the hood itself.

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