Problem with s.u. h6 carbs

[gabriele]

hi, i'm gabriel from italy and i triumph tr3a owner

dear sir/madam

i have some prblem with my s.u. h6 carburettor fit in tr3 built in 1960

unfortunatly here in tuscany where i live no one understand the problem cause

 

i explein:

 

the mixture seem to rich even though the nut mixture is almost fully up

 

the sparks are different for the same carburattor (see attachment) to rich one too weak the other (that for the 2 carburettor)

 

i ask help a lot of people here in italy but nobody know the way to solve it

 

could you help me ?

 

 

 

Regards

 

Gabriele

[Ashley James]

The jets should be 1mm below the bridge and you can set them with a vernier gauge.

 

Probably the Carbs are flooding because the needle valves are faulty. These are good and cure the problem:

 

http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=18415

 

Take the lids off the float chamber turn them upside down and the two legs should be 7/16" from the face of the lid. Use the blunt end of a drill as a gauge.

 

Best of luck

 

Ashley

 

Other SU spares www.Burlen.co.uk

[Menno van Rij]

Hi Gabriel,

 

Welcome to the Forum! I hope we can help you. Since it's hard to translate the English terms to Italian, I think it's an idea to have a look at this:

You Tube videos on SUs Lots of info!

 

You can also contact these guys overhere in Holland (in English) BCCP carbs

 

Menno

Edited May 14, 2011 by Menno van Rij

[stuart]

Maybe I am wrong but my understanding is the plugs are laid out in order and that either 1 and 3 are running rich or 2 and 4. Either way I would try a compression test first of all and then a check to make sure that you have a healthy spark at the two "rich" ones.

Stuart.

[JDB]

Parlo po 'di italiano. Forse, provare con un kit di Carb ricostruzione o cosa Ashley consigliati, un Jet-Grose.

 

Buona fortuna,

JDB

[sidescreen]

Gabriele,

 

Another suggestion, something wrong with one of your leads from distributor to sparkplug no. 3.....?

 

Best of luck - Raymond

[gabriele]

Gabriele,

 

Another suggestion, something wrong with one of your leads from distributor to sparkplug no. 3.....?

 

Best of luck - Raymond

 

Hi Ryamond, many thanks for your help

all leads was changed

[gabriele]

Parlo po 'di italiano. Forse, provare con un kit di Carb ricostruzione o cosa Ashley consigliati, un Jet-Grose.

 

Buona fortuna,

JDB

 

ciao jdb grazie 1000 per l'aiuto

il kit l ho già cambiato cio' che non ho cambitao sono i grose jet e li cambiero' a breve

[gabriele]

Maybe I am wrong but my understanding is the plugs are laid out in order and that either 1 and 3 are running rich or 2 and 4. Either way I would try a compression test first of all and then a check to make sure that you have a healthy spark at the two "rich" ones.

Stuart.

 

hi Stuart many thanks for your help

the plugs are laid in order and 1 - 3 are running rich than other (very strange becuse for the same carb we have one rich other less rich)

[gabriele]

Hi Gabriel,

 

Welcome to the Forum! I hope we can help you. Since it's hard to translate the English terms to Italian, I think it's an idea to have a look at this:

You Tube videos on SUs Lots of info!

 

You can also contact these guys overhere in Holland (in English) BCCP carbs

 

Menno

 

Hi Menno many thanks for you help was a pleasure to meet this forum and trough it i'm sure to solve the priblem

i saw youtube videos before control the carbs

[gabriele]

Hi Gabriel,

 

Welcome to the Forum! I hope we can help you. Since it's hard to translate the English terms to Italian, I think it's an idea to have a look at this:

You Tube videos on SUs Lots of info!

 

You can also contact these guys overhere in Holland (in English) BCCP carbs

 

Menno

 

Hi Menno many thanks for you help was a pleasure to meet this forum and trough it i'm sure to solve the priblem

i saw youtube videos before control the carbs

[gabriele]

The jets should be 1mm below the bridge and you can set them with a vernier gauge.

 

Probably the Carbs are flooding because the needle valves are faulty. These are good and cure the problem:

 

http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=18415

 

Take the lids off the float chamber turn them upside down and the two legs should be 7/16" from the face of the lid. Use the blunt end of a drill as a gauge.

 

Best of luck

 

Ashley

 

Other SU spares www.Burlen.co.uk

 

hi Ashley many thanks for you help

i will buy this monday the new grose jets, could be the grose jets to make one plug more richer than close plug in the same carb?

regards

Gabriele

[Ashley James]

Gabriel

 

I don't know, but if everything is set correctly the car should run correctly, so best start with the Carbs because they make the biggest difference.

 

You can only tell what the mixture is like by driving at different continuous speeds, cutting the engine, coasting to a standstill and checking the plugs. If the engine is ticking over for some time,5)3 plugs will get sooty.

 

Best of luck

 

Ashley

[Peter Cobbold]

Gabriele,

Welcome!

 

As Stuart says, this might not be a fault with the carbs. As I see from your reply to Stuart you know both plugs should get the same mixture when fed by the same carb.

 

So I would have a good look at the distributor- especially wear that might allow the shaft to 'wobble'or rotate unevenly. That could give different 'dwell angles' for plugs 1 and 3 compared with 2 and 4 *. But the wear would have to be bad - so it should be very obvious. It might be a weak centrifugal advance spring. I am just guessing as it is an unuusal symptom, that I have not seen before on a carburetted engine.

 

(* If the dwell angle is too short the coil has too little time to 'recharge' and the spark will be weak and the flame spread retarded. So the mixture will not burn fully, sooting the plugs.)

 

Peter

 

An afterthought:

Firing order 1342 ??? so a bent distributor shaft would allow point gap, and dwell angle, to change in the pattern you see on the plugs. Gap could be OK on plugs 2 and 4 (on one side of the shaft) but too small on 1 and 3 ( on other side of shaft). So check points gap at each lobe.

Peter

Edited May 17, 2011 by Peter Cobbold

[67_gt6]

Gabriel

 

I don't know, but if everything is set correctly the car should run correctly, so best start with the Carbs because they make the biggest difference.

 

You can only tell what the mixture is like by driving at different continuous speeds, cutting the engine, coasting to a standstill and checking the plugs. If the engine is ticking over for some time,5)3 plugs will get sooty.

 

Best of luck

 

Ashley

 

 

disagree, 90% of "carb problems" are electrical. particularly when 2 plugs being served by the same carb are showing different soot levels. could be shaft wobble as Peter suggests. Pertronix would sort that

 

Andy

[gabriele]

Gabriele,

Welcome!

 

As Stuart says, this might not be a fault with the carbs. As I see from your reply to Stuart you know both plugs should get the same mixture when fed by the same carb.

 

So I would have a good look at the distributor- especially wear that might allow the shaft to 'wobble'or rotate unevenly. That could give different 'dwell angles' for plugs 1 and 3 compared with 2 and 4 *. But the wear would have to be bad - so it should be very obvious. It might be a weak centrifugal advance spring. I am just guessing as it is an unuusal symptom, that I have not seen before on a carburetted engine.

 

(* If the dwell angle is too short the coil has too little time to 'recharge' and the spark will be weak and the flame spread retarded. So the mixture will not burn fully, sooting the plugs.)

 

Peter

 

An afterthought:

Firing order 1342 ??? so a bent distributor shaft would allow point gap, and dwell angle, to change in the pattern you see on the plugs. Gap could be OK on plugs 2 and 4 (on one side of the shaft) but too small on 1 and 3 ( on other side of shaft). So check points gap at each lobe.

Peter

 

 

hi

Peter Many thanks

what 's mean shaft to "wobble" and dwell angle ?

the points gap was check and is the same for all sparks

[Ashley James]

Gabriel

 

As long as the gap is the same for all sparks and the rotor bearing doesn't have play, I doubt you'll have trouble. Obviously it's wise to make sure that if the plug leads are modern and resistive that they haven't gone open circuit or very high resistance and that there is no sign of arcing on the rotor arm or in the cap, but I'm inclined to think it's a question of the SUs needing careful setting.

 

The most common fault is flooding because the needle valves aren't sealing properly or because the float height isn't correct. People adjust the jets wrongly to compensate, so make sure they are exactly 1mm below the jet bridge with the shoulder of the needle level with the face of the dashpots.

 

Finally take the dashpots off, back off the tickover screw till the butterflies grip a 1.5 thou feeler gauge equally. Take time until you get this exactly right and the car will tick over better and pull more cleanly from low revs.

 

Best of luck

 

Ashley

[Ashley James]

One final thought is that if the throttle spindles have worn air will get in and make it very difficult if not impossible to get a reliable tickover. Burlen supply new spindles and the carbs can be re-bushed if wear is considerable.

 

Ash

[Peter Cobbold]

hi

Peter Many thanks

what 's mean shaft to "wobble" and dwell angle ?

the points gap was check and is the same for all sparks

 

 

Gabriele,

So the disy shaft is not bent.

Maybe the bearings are worn: can you move the shaft side to side? It might be that the shaft sits centrally when not rotating - so gaps measure OK on all cylinders - but allows the shaft to move to alter the gap when its rotating. A strobe ( timing light) on crank will show up a serious timing fluctuation.

Thats the next step.

I remain convinced its not the carbs.

Have you checked plug leads as Stuart said earlier?- eg compare the sparks in the dark.

AAAh just seen your earlier post- new leads.

Check inside of distributor cap for 'tracking', or fit new cap.

Peter

Edited May 26, 2011 by Peter Cobbold

[Hicks51]

Hi Gabriele,

 

I haven't checked all of the replies in detail so perhaps this is repeating advice, but have you tried starting the engine in darkness and checking under the bonnet?

 

I had a similar problem to you and I found that my brand new leads were sparking (through the insulation!) to the fuel line and between each other. Also, there were sparks from the centre of the coil to both sides. In daylight, I could hear "ticking" of an electrical short and had an intemittent misfire, but it was difficult to pinpoint the problem until it was dark. (Some of this was my fault for not cutting the new leads to the correct length to begin with, but I never expected shorting through the insulation, which was not split.) It took me only a few minutes to fix the problems and now the car starts and runs very well.

 

How old is the petrol in your tank?

I didn't do many miles while I worked on my TR3, so I had petrol sitting in the tank for well over a year. I had problems starting and running it and kept adjusting the carbs to try and fix the problem. Eventually, I remembered that old petrol goes off and once I had put fresh fuel in and fixed the electrical problems above, everything worked fine.

 

Just a thought.

 

Good luck,

Brian.

Edited May 26, 2011 by Hicks51

[bnw]

When you check for that spark dancing under the bonnet, it helps to wet the wires and cap with a spray bottle of water with a little alcohol added as a wetting agent. This will always bring out the worst of your secondary ignition system.

[Ashley James]

I recommend the purchase of a cheap multimeter and using it to measure the resistance of the plug leads. http://www.amazon.co.uk/Draper-52320-Digital-Multimeter/dp/B0001K9UZA

 

In this instance he has new ones, so they should be okay, but a test does no harm.

 

I'd be wary to testing sparks under bonnet because it is awfully easy to start a fire.

 

Ash

[Peter Cobbold]

If the leads to the two 'rich' plugs are adjacent in the distributor cap HT might be tracking between them on the inside of the cap, making spark at both plugs weaker. Try new cap.