I've noticed this evening that the grill is missing from the GT6. It was there on Monday morning when I was finishing off the work to replace the timing chain, tuning the carbs etc. But I did take the car for a bit of a blast on Monday afternoon and I guess it must have fallen off!
So I'll have to find a replacement, at least it's cosmetic and doesn't stop the car being on the road.
Wednesday, 29 May 2013
Monday, 27 May 2013
Tuning The Carbs
I know a few Triumph owners who shy away from tuning the carbs on their cars but really it's not rocket science if you have the right tools. Thought I'd put a blog article up explain how to tune the Stromberg carbs as fitted to the GT6 and many other Triumphs as it may help a few folks take the plunge an tune their own carbs.
Firstly, (or should I say lastly), always leave tuning the carbs until last. Set up the tappet clearances, check the plugs gap, if you have points set up the points gap (not necessary with electronic ignition), finally set the ignition timing with a strobe.
Next here are my recommended tuning tools, a Gunson's colourtune for setting the mixture (available for about £25 on amazon or ebay) , a webber syncrometer for balancing the carbs (about £36 on ebay) and if you have the later type CDSEV Strombergs the essential mixture adjusting tool (about £10 from Triumph Specialists).
Get the car up to normal operating temperature by taking it out for a run or leaving it idling for a while.
Then it's time to set the mixture. The Colourtune is a sparkplug with a see through section that allows you to see the explosions in the combustion chamber. When the mixture is set right the explosion burns blue in colour, if it's too rich then it burns Orange. The trick is to set the mixture up so it's just lean enough to burn blue. Screw in the colourtune plug in place of no 6 spark plug. Fit the shroud assembly with the little mirror and the HT extension and plug in the HT lead. If you have CDSEV carbs take the damper out of the carb top of the rear carb.
Next start the engine and put the adjuster tool down the damper hole, make sure the outer part is engaged in the slot of the damper tube. Look into the colourtune reflection in the mirror and see the colour of the explosion, if it's orange then you are ruining rich which is where we need to start. If not turn the adjuster allen key clockwise until the mixture richens and the explosions are orange. Then turn the adjuster anti clockwise carefully until the explosions are just in the blue mixture range. If you have the earlier type of carbs the adjuster is a hex adjuster under the float chamber. Anti clockwise for richer mixture, clockwise to weaken.
Next repeat the above with the colourtune in number 1 plug position and adjustments on the front carb.
Afterwards ensure that the damper pots are topped up with oil, I use 20-50 engine oil, some people prefer thinner oil such as 3 in one. Replace the damper pistons.
Now it's time to balance the carbs and set the idle. Undo the clamp on the linkage on one of the carbs so that the carbs operate independently.
Remove the air filters. Start the engine and measure the airflow using the Synchrometer.
Adjust the throttle stop screws of each carb until the same reading is obtained.
Then increase or decrease the idle speed using the throttle stop screws a bit at a time on each carb rechecking the balance as you go until you get the minimum tickover speed where the engine still ticks over smoothly. The manual says 600 - 650 rpm but I normally set it between 800 and 1000. Rev both carbs independently and recheck adjusting as necessary. Then when happy with the adjustment re-tighten the linkage screw.
Replace the air filters and that's it you are done. Take the car for a test drive. If you've done the job properly the car will run like a dream! However, if it has a flat spot or hesitation when accelerating then the mixture may be too weak so repeat the mixture adjustment stage with the colourtune and recheck the balance/idle mixture.
Firstly, (or should I say lastly), always leave tuning the carbs until last. Set up the tappet clearances, check the plugs gap, if you have points set up the points gap (not necessary with electronic ignition), finally set the ignition timing with a strobe.
Next here are my recommended tuning tools, a Gunson's colourtune for setting the mixture (available for about £25 on amazon or ebay) , a webber syncrometer for balancing the carbs (about £36 on ebay) and if you have the later type CDSEV Strombergs the essential mixture adjusting tool (about £10 from Triumph Specialists).
Get the car up to normal operating temperature by taking it out for a run or leaving it idling for a while.
Then it's time to set the mixture. The Colourtune is a sparkplug with a see through section that allows you to see the explosions in the combustion chamber. When the mixture is set right the explosion burns blue in colour, if it's too rich then it burns Orange. The trick is to set the mixture up so it's just lean enough to burn blue. Screw in the colourtune plug in place of no 6 spark plug. Fit the shroud assembly with the little mirror and the HT extension and plug in the HT lead. If you have CDSEV carbs take the damper out of the carb top of the rear carb.
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| Colourtune installed (this is in No 6 cylinder) |
Next start the engine and put the adjuster tool down the damper hole, make sure the outer part is engaged in the slot of the damper tube. Look into the colourtune reflection in the mirror and see the colour of the explosion, if it's orange then you are ruining rich which is where we need to start. If not turn the adjuster allen key clockwise until the mixture richens and the explosions are orange. Then turn the adjuster anti clockwise carefully until the explosions are just in the blue mixture range. If you have the earlier type of carbs the adjuster is a hex adjuster under the float chamber. Anti clockwise for richer mixture, clockwise to weaken.
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| Orange Explosion visible in the reflection of the colourtune in the little mirror. |
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| Blue Explosion visible, mixture set correctly. |
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| Using the adjuster tool on CDSEV carbs. |
Next repeat the above with the colourtune in number 1 plug position and adjustments on the front carb.
Afterwards ensure that the damper pots are topped up with oil, I use 20-50 engine oil, some people prefer thinner oil such as 3 in one. Replace the damper pistons.
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| Topping up the carb damper oil |
Now it's time to balance the carbs and set the idle. Undo the clamp on the linkage on one of the carbs so that the carbs operate independently.
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| Slacken one of the linkage clamps |
Remove the air filters. Start the engine and measure the airflow using the Synchrometer.
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| Measuring the airflow using the Syncrometer |
Adjust the throttle stop screws of each carb until the same reading is obtained.
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| Adjusting a throttle stop screw to set the balance/idle speed. |
Then increase or decrease the idle speed using the throttle stop screws a bit at a time on each carb rechecking the balance as you go until you get the minimum tickover speed where the engine still ticks over smoothly. The manual says 600 - 650 rpm but I normally set it between 800 and 1000. Rev both carbs independently and recheck adjusting as necessary. Then when happy with the adjustment re-tighten the linkage screw.
Replace the air filters and that's it you are done. Take the car for a test drive. If you've done the job properly the car will run like a dream! However, if it has a flat spot or hesitation when accelerating then the mixture may be too weak so repeat the mixture adjustment stage with the colourtune and recheck the balance/idle mixture.
Running again
Up and running again. Tried setting the static timing with a multimeter but a bit difficult with electronic ignition and it was way out. Car started just but then after setting with a strobe all was well.
Just been for a drive and its running well with that healthy 6 pot wail coming from the exhaust.
I now need to retune the carbs as they were played with somewhat while trying to get the thing going when it broke down, but time to celebrate with a cuppa first!
Video clip of the running engine below!
Sunday, 26 May 2013
Cleaning and Re-assemby
Made some good progress today and the GT6 is nearly back in one piece.
Fitted the new oil seal and timing chain tensioner to the timing chain cover after cleaning up 20 years of grime off the cover from an oil leak that has been there for ages. As per the manual I made up a hooked tool for pulling the tensioner into place when replacing the cover. I use blue hylomar sealant on the gasket so hopefully it won't leak.
The tappets were checked and reset as necessary. The Water pump and housing and Radiator were refitted. The exhaust put back on along with other parts that were removed during fault finding like the air cleaners and the battery put on charge.
Tomorrow I'll add the spark plaugs. HT leads and reset the ignition timing and then it will be time to try and start the beast. Fingers crossed all will be well and the GT6 will be back on the road ready for a blast tomorrow afternoon.
Fitted the new oil seal and timing chain tensioner to the timing chain cover after cleaning up 20 years of grime off the cover from an oil leak that has been there for ages. As per the manual I made up a hooked tool for pulling the tensioner into place when replacing the cover. I use blue hylomar sealant on the gasket so hopefully it won't leak.
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| New oil seal and tensioner fitted |
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| Hook tool made up out of an old tent peg for pulling the tensioner into place while refitting the cover. |
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| Cover refitted, blue hylomar used to seal the gasket. |
Tomorrow I'll add the spark plaugs. HT leads and reset the ignition timing and then it will be time to try and start the beast. Fingers crossed all will be well and the GT6 will be back on the road ready for a blast tomorrow afternoon.
Saturday, 25 May 2013
Well thats the tricky bit done
Started replacing the timing chain and sprockets today, as expected the new sprockets have no marks and what with the timing being so far out it was best to start from first principles and set up the timing from scratch.
Firstly having taken the old sprockets and chain off the extent of the wear was really visible. The Crankshaft sprocket was unbelievably worn, I thought the teeth tips had broken off but having looked at the part they have just worn and bent. The camshaft sprocket was a bit worn but nowhere near as bad.
Next it was time to measure TDC. A little tip from some videos on you tube from MOSS is that a BMW Mini wheel bolt is the same thread as a spark plug (14mm diameter x 1.25mm pitch). I bought one on ebay for £1.25!. This was screwed down the plug hole. A timing disc was printed off from the Internet and laminated and then fitted to the end of the crankshaft. I then made up a pointer out of a tent peg and a paper clip which was mounted on one of the timing cover studs. I then turned the engine over until the piston was stopped by the bolt down the plug hole and took a reading from the disc. I then turned the engine backwards until the piston was topped again and took another reading. TDC is then halfway between the two readings, this was marked off on the timing disc and a mark scribed on the crankshaft and the engine front plate to mark TDC.
It was then time to fit the crankshaft sprocket, This turned out to be pretty difficult to line up the woodrufe key with the slot in the sprocket and the new one was a very tight fit and had to be carefully tapped into place with a hammer.
The camshaft sprocket was then fitted without a chain and the sprocket alignment checked with a straight edge, all was still in alignment.
The camshaft sprocket was then rotated until both valves of No 1 cylinder were just opening/closing with the same clearance, AKA the rocking point. This is how the valves should be at TDC for correct timing.
The sprocket was then carefully removed without altering the camshaft position and refitted with the chain. A bit of trial and error to align the camshaft bolt holes by trying different tooth positions and alternative bolt holes and all was aligned. Camshaft bolts were then fitted and a check that the crank was still at TDC and the valves at rocking point. Once confirmed that the timing was set I scribed some timing marks to make the job easier if it ever has to come apart again.
The rest of the job should be a bit more straight forward. Need to clean up the timing cover, fit a new oil seal and timing chain tensioner and then assemble with a new gasket. Tappet clarences adjusted. Ignition timing needs to be set approximately. Plugs need to be replaced. Water pump housing replaced with a new gasket, radiator replaced and exhaust put back on and then it should be ready to try and start the engine.
Firstly having taken the old sprockets and chain off the extent of the wear was really visible. The Crankshaft sprocket was unbelievably worn, I thought the teeth tips had broken off but having looked at the part they have just worn and bent. The camshaft sprocket was a bit worn but nowhere near as bad.
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| Crankshaft sprockets old and new, the teeth on the old one have worn and bent over severely. |
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| Camshaft Sprocket nowhere near as worn although the teeth are a bit hooked. |
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| BMW Mini wheel bolt screwed into the plug hole of No 1 cylinder. |
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| Timing Disc and pointer arrangement to find TDC |
The camshaft sprocket was then fitted without a chain and the sprocket alignment checked with a straight edge, all was still in alignment.
The camshaft sprocket was then rotated until both valves of No 1 cylinder were just opening/closing with the same clearance, AKA the rocking point. This is how the valves should be at TDC for correct timing.
The sprocket was then carefully removed without altering the camshaft position and refitted with the chain. A bit of trial and error to align the camshaft bolt holes by trying different tooth positions and alternative bolt holes and all was aligned. Camshaft bolts were then fitted and a check that the crank was still at TDC and the valves at rocking point. Once confirmed that the timing was set I scribed some timing marks to make the job easier if it ever has to come apart again.
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| New Sprockets and timing chain fitted, valves timed and new timing marks scribed. |
Monday, 20 May 2013
Parts Ordered and Timing Disk "Obtained"
I ordered the timing chain kit and sprockets on line last night so they should be here before the weekend. As this weekend is a bank holiday and I'm also free from the kids I should have plenty of time to get stuck in and get the car back together.
A couple of people suggestted after I'd already ordered the parts that it would be a good idea to upgrade from the standard single chain to the duplex version as used on the 2.5L Engines. Too late now as the parts for a single timing chain set are on their way but probably a good bit of advice. Still if the standard version lasts as long as the first one did (about 70,000 miles and 20 years!), I reckon I should need a full Engine rebuild before then anyway so no worries.
One other useful bit of information, don't bother buying a timing disc if you need to do your valve timing as there are plenty of timing disc images on the internet that can be downloaded for free and printed off on photo paper or card. here's a link to one I downloaded in case you need it:- http://www.gabma.us/tools/DegreeWheel.bmp
A couple of people suggestted after I'd already ordered the parts that it would be a good idea to upgrade from the standard single chain to the duplex version as used on the 2.5L Engines. Too late now as the parts for a single timing chain set are on their way but probably a good bit of advice. Still if the standard version lasts as long as the first one did (about 70,000 miles and 20 years!), I reckon I should need a full Engine rebuild before then anyway so no worries.
One other useful bit of information, don't bother buying a timing disc if you need to do your valve timing as there are plenty of timing disc images on the internet that can be downloaded for free and printed off on photo paper or card. here's a link to one I downloaded in case you need it:- http://www.gabma.us/tools/DegreeWheel.bmp
Sunday, 19 May 2013
Lack of Teeth!
Stripped down the front of the Engine on the GT6 tonight and the issue with the valve timing was blatently obvious.
The tips of all the teeth on the Crankshaft sprocket are missing and the timing chain has worn very loose. The camshaft sproket teeth are also pretty worn. No wonder the valve timing was able to slip.
Sounds like a fairly easy fix then, timing chain kit and a pair of new sprokets to be ordered and I can hopefully get it sorted next weekend.
Only other part to order is a new water pump housing gasket, the water pump housing had to be removed to get the timing chain cover off due to a pretty crap design by Triumph...
The tips of all the teeth on the Crankshaft sprocket are missing and the timing chain has worn very loose. The camshaft sproket teeth are also pretty worn. No wonder the valve timing was able to slip.
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| Crankshaft spocket (at the bottom) has the tips of all the teeth worn away. |
Sounds like a fairly easy fix then, timing chain kit and a pair of new sprokets to be ordered and I can hopefully get it sorted next weekend.
Only other part to order is a new water pump housing gasket, the water pump housing had to be removed to get the timing chain cover off due to a pretty crap design by Triumph...
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