Triumph twin Strombergs...

[b_caswell]

Re: Triumph twin Strombergs...

Well it was very warm today, the running lean wont have helped and possibly too far advanced can also cause it to run hot.

But the breather set up needs to draw in from the rocker, if you connect the carbs together it will be running far too rich plus the crankcase is meant to run with a negative pressure.

One problem with an electric fan is it does restrict the air flow through the radiator as its in the way.

Being a cast iron head it should survive but I would check out the thermostat as they don't like it when they get too hot either sticking open or failing in the shut position.

[David]

Re: Triumph twin Strombergs...

Well, it's running OK now with a replacement thermostat. Run up to Kop Hill Climb and back at the weekend and the gauge fluctuates a bit hot/hotter/hot as you would expect when the stat opens and closes when running on open roads and then in town.

Thanks to Andy Smith, local Vitesse owner for loaning an 82 degree stat until I could get one.

David.

[David]

Re: Triumph twin Strombergs...

Temperature getting too high when hitting the gas hard, so will check timing and fuel mixture soon, thanks for Adrian for lending me his ColourTune!

[b_caswell]

Re: Triumph twin Strombergs...

Keep your eye on the fuel gauge!! if it goes up towards full at the same time that the temp gauge shows hot it could be the voltage stabilizer playing up.

[greyV8pete]

Re: Triumph twin Strombergs...

Temperature getting too high when hitting the gas hard, so will check timing and fuel mixture soon, thanks for Adrian for lending me his ColourTune!

If the gauge really is giving a true reading and timing is correct it looks to me like it is running far too lean at wide open throttle and needs sorting asap before any lasting damage occurs. I would check the throttle needles are correct for your engine spec. The following links may help:

http://www.rimmerbros.co.uk/Item--i-GRID007997

http://www.gowerlee.dircon.co.uk/spares.html#Stromberg

Peter.

[b_caswell]

Re: Triumph twin Strombergs...

Another point to think about considering the condition your replacements were is the temp compensators not working correctly.

http://www.vtr.org/maintain/temp-compensators.shtml

ignore the header and scroll down the page.

The alternative advice is to just screw them shut.

[David]

Re: Triumph twin Strombergs...

Thanks guys,

Used the ColorTune today, couldn't start from too rich as carbs don't seem to want to adjust that far but otherwise the colours I observed are in keeping with the chart linked above once richening the needles another quarter turn. But if anything at higher revs seem to go a bit too light blue which probably means a bit lean so I have retarded the timing a tad for now.

One thing that has confused me is looking at th seething for emission control cars static timing is 6 degrees BTDC and 4 degrees AFTER top dead centre at tick over. Much different to the 13 degree BTDC on a standard Vitesse MK2 engine. The carbs I had are CD3's but I've no idea if the engine has the emissions control cam etc (even though the original carbs were earlier emissions control carbs) so am reluctant t try the single digit settings. Anyone got any experience with that on a MK3 GT6?

I hope this thread is of use to someone else eventually!

David.

[b_caswell]

Re: Triumph twin Strombergs...

13 degrees was when we had 5 star 101 octane fuel. Start at 8 deg and then advance a little at a time until you get pinking under load then back off a little.

[David]

Re: Triumph twin Strombergs...

13 degrees was when we had 5 star 101 octane fuel. Start at 8 deg and then advance a little at a time until you get pinking under load then back off a little.

Thanks Ben. So for the ears of others reading as well, when I advance from 8 deg would that number be going higher or lower, towards 13 deg or further away. Maybe an explanation of what advance and retard is in relation to TDC would be good. I always get confused!

David.

[philcoyle]

Re: Triumph twin Strombergs...

Easy way to look at timing.
Look at the dial on a clock, 12o'clock is when the spark plug should fire off the air /fuel mixture, call this Top Dead Centre (TDC). A clock has 60 minutes each minute 60 seconds = 60x60 360 degrees. 3 o'clock =15 deg/min AFTER TDC or 12 o'clock 9 o'clock is 15 deg/min BEFORE 12 o'clock.
If your timing is 13 deg and it is before TDC static, advancing the timing to 5 deg is closer to TDC so you are retarding the timing because it is firing later, as in counting down from 13 to 5.
A whole 8 deg later or retarding the timing, to advance the timing you would increase the number from 13 to say 15.
Bigger the number before TDC the more advanced the timing is.
The smaller the number before TDC the more retarded the timing is until you PASS TDC and then it starts 0 degrees and then increases 1,2,3, etc. just like a clock, this is then retarding the timing because it is after TDC.
Now have a cup of tea and a biccy read it a few times, draw a clock face 12, 3, 6,9 , from 6 to 12 advancing. From 12 to 6 retarding. Then look at your engine rotation and which way around your distributor rotates, if it rotates clockwise, to advance the timing turn the distributor anti clockwise or do the reverse to retard it.
I hope this is not too techy, but after you read it a few times it should get clearer, and just think about it as one revolution of one piston, because everything else has to follow.
Phil

[philcoyle]

Re: Triumph twin Strombergs...

I don't want to be a doom and gloom merchant, but, after reading your earlier posts about the faulty thermostat it is possible that the engine has been fried due to over heating and losing coolant'
Run the engine with the radiator cap removed, fill the radiator right up to the top, if water level increases as it gets warmer its ok, if it starts to push water out excessively then I'm afraid you will have head gasket failure, which due to the history of thermostat problem it's inevitable.
Phil

[David]

Re: Triumph twin Strombergs...

Thanks Phil,

As I thought on the timing, but hadn't though about the after TDC workings out so that's a help.

I ran the engine for a long time yesterday and no significant change in water levels, water pumping out, bad running, oil contamination etc. So all OK I think!

[philcoyle]

Re: Triumph twin Strombergs...

Hi David,
I hope it wasn't too confusing or techy for you, I do try not to be too pedantic or techy as it helps no-one, if there is any part you are not too sure about don't be afraid to ask, when I was an apprentice mechanic my tutor/mentor Gordon Barefoot would say "if you don't ask you wont find out" very true.
Retarding the timing will lose you power, too much advance will cause " pinking "or knocking as it is called nowadays, pinking should really be called PINGING as it is the noise the pistons make when too much timing advancement will make the pistons rattle and can blow a hole in them from pre-detonation, firing too early. Not a nice sight when you remove a cylinder head and a piston has melted.

Back in the days of " that will do technology", one idea was to set the timing up statically (usually with a bulb ) in advance mode, then hard acceleration up the road, if it pinked we would screw it backwards/retard it until we were happy with the performance. And then strobe lights and Krypton diagnoses machines came in, Shaw Taylor and the Silver Wheel Club, and now obd1 and obd2 etc. And now car forums where you can ask anything and hopefully someone has the answer.
Phil

[b_caswell]

Re: Triumph twin Strombergs...

Back in the days of " that will do technology", one idea was to set the timing up statically (usually with a bulb ) in advance mode, then hard acceleration up the road, if it pinked we would screw it backwards/retard it until we were happy with the performance. And then strobe lights and Krypton diagnoses machines came in, Shaw Taylor and the Silver Wheel Club, and now obd1 and obd2 etc. And now car forums where you can ask anything and hopefully someone has the answer.
Phil[/QUOTE]

Phil, what do you mean back in those days?? that how I still do it and the Triumph workshop says you do it. You don't need all these modern bits of kit.

[David]

Re: Triumph twin Strombergs...

You don't need all these modern bits of kit.

Phew, glad my light bulb will do the job...

Maybe Phil has a modern engine in his car, with modern bits? Phil?