CD150: Coil springs & spring-loaded pins

[Nortonius]

I was just perusing Triumph's owner's handbook for my 13/60 whilst trying to get the hang of the ignition timing process – sorry, I've only had the car since early August, and stuff like this is still a bit foggy for me. Anyway, I turned a page and noticed that the diagrams for the carburettor include a 'coil spring' between the top cover and the diaphragm/air valve (Fig. 95, p. 56, item 15 in the owner's handbook, if you have a copy).

 

I'm guessing the diagrams are generic for the CD150, in that the carb was used for different applications, so maybe some had this coil spring and some didn't. Point is, mine doesn't. Should it?

 

While I'm here, none of the manuals seem to mention the 'spring-loaded pin' that lurks below the top of the carb, that can be used to check the mixture: am I right in thinking this only wants a light touch when in use, rather than being pushed up as far as it'll go? The same diagrams seem to show that its head actually pushes against the air valve when it's lifted. TIA

[Pete Lewis]

Not all have a spring for the piston , some have heavier weghted diaphragm retainers

Theres a wide range of specifications and evolutions

13/60 CD150 does not have a damper spring.

 

yes lifting pin is light touchy feely job , just touch the piston and raise it a 2 mm certainly not

Yank it up

 

amd needs air filter on as this affects mixture /manifold vacuum

and you ars looking for a small change in revs like up 50 for a couple of seconds if rich

down 50 for lean and no change about right

its not going to make major obviuos changes.. light touch small deviations

 

pete

[Nortonius]

Ok, so no spring for the 13/60 – the diaphragm retainer did seem a bit heavy when I had most of the carb apart. Yes, it occurred to me to keep the air filter on when playing with the spring-loaded pin: it suddenly struck me that it was a much more grown-up way of checking the mixture than sticking a screwdriver or heaven knows what else into the carb to lift the air valve! I couldn't quite believe it when I first read that, it seemed an insane invitation to destroy the engine! Maybe I'm just more at home with Amal bike carbs, where the cable pulls directly on the throttle slide, and there is a coil spring... Yet the manuals don't mention the pin! Hey ho. Thanks again Pete!

[Pete Lewis]

And use 20 grade or 20/50 engine oil in the dashpot ,, dont want any cats pee

its damper to richen up on acceleration, daft ideas like 3 in 1 is better is defying its purpose

 

I can never understand the idea of lifting the piston with the filter missing , it makes a world of difference to the mixfure, same as fitting any free flow aftermarket types you have to change the needle sppec to compensate the now lean mixture

 

pete

[Nortonius]

I'm sure I've seen somewhere that 20 grade oil is hard to come by. I had a bottle of 20 grade fork oil for a motorbike knocking around when I got my 13/60, so I used that, it seemed ideal since it largely serves to damp the forks – unless anyone knows better. Otherwise, if 20 grade can't be found, go to a motorbike shop. Mind you, every time I look in the top of the carb the oil needs topping up – foggy though things still are, I've been very busy going over everything I can think of or reasonably get at on this 46-year-old car, so I've fiddled with the carb a lot. I've tried removing and installing the damper super-slowly but it doesn't seem to make any difference to how much oil is left in there.

 

I thought that about the air filter and the mixture too, but assumed Triumph thought it'd be ok... Did early versions of the CD150 not have that spring-loaded pin, maybe, so the only way to lift the air valve was to get in there with a tool...?

[dougbgt6]

20/50 engine oil is fine for dashpots. If it's disappearing quickly there's an "O" ring on the piston that probably needs replacing. Did mine 3 years ago and I think they need doing again!

[Pete Lewis]

as emmision controls became more included things that enabled twiddling dis appeared , so later CDSE probably wont have one

CD and CDS  generally did have one 

 

others with no spring  fitted that spring to mind are the 1600 and 13/60  

 

and after all the years you dont always know who swapped what  and the original design gets diluted

 

adding a spring will richen the mixture across the range as the extra  air flow velocity across the jet pulls more fuel in unless you modify the needle,  its a balancing act to get the needle profile the piston postion and air flow to all make sense of the air fuel ratio

 

following Dougs clue about 0 rings these were on CDSE with biased needle and adjustment  is to the needle from the dashpot tube ,

if its got a fixed needle and jet adjusts from under the float chamber then they dont have a 0 ring 

Pete

[Nortonius]

Thanks Pete – there's no O-ring on mine, but there was an 'extra' one about that size in the Zenith service kit I got recently – fortunately my needle's fixed and the jet adjusts as you say, so I'll leave it alone.

 

That reminds me though, I got the Zenith kit because the O-rings on the jet screw and jet assembly had failed – the one on the jet screw came to pieces as I removed it, so probably was original – but the kit seemed a bit odd. Besides a new jet and other bits and bobs it included nice, shiny new screws for the carb top, but no metering needle! What?! The old screws were fine, but no needle?! And I'd found that my metering needle was bent...! So I ordered a new one from one of the usual suspects. Is this normal, or should I get onto Burlen/Zenith about their service kits?

[Pete Lewis]

needles get bent when the jet has not been centralised ( slacken the big nut 1/4 turn allows the jet to centre about the needle  re nip when all is good)

if its out of line and  forced down it bends .

 

the cause of many a sticking piston.

 

many kits never contain the bit thats needed ...you may have a load of float joints  they are all different some dont seal on odd corners as evolution made progress.  

 

Burlen are generally good,  if you use rimmers the click on part number gives the kit content

 

all suppliers seem to supply different kit content. guess it depends where they get them from

 

and kits can be 'general'    wheres as needles/springs etc   are 'specific'

 

so sold seperately

 

some kits will contain O rings for temperature compensators bodies or needle seals used on CDSE 

 

Pete

 

Pete

[Nortonius]

Interesting... The kit I got was about half the price wanted by Rimmer's, where I didn't actually look, I just followed a tip I saw for a 'carb specialist', possibly somewhere in this forum. Maybe the lower price explains it, even though it came in a nice, new Zenith box... I think in future I'll just order bit by bit, it'll still be cheaper! Thanks again.

[Gully]

20/50 engine oil is fine for dashpots. If it's disappearing quickly there's an "O" ring on the piston that probably needs replacing. Did mine 3 years ago and I think they need doing again!

Is that the o-ring around the needle adjusting screw which is retained by the infamous spragg washer? Have thought about doing mine, but keep deciding that topping up the dash pots more often is considerably easier!

 

Gully

[dougbgt6]

Yes, the infamous spragg washer! Last time I replaced the "O" rings one washer spragged the length of the garage, never to be seen again!

 

The Rimmer kit is expensive because it's universal and contains every bit for every Stromberg variation. Except the jet for the late GT6 mk3! I realized to late that the kit had the wrong jets.

 

Although Rimmers stock both early and late jets separately, the universal kit comes only with the early jets.

 

To add insult to injury they refused to swap the jets because my jets were part of a kit.

[Gully]

Yes, the infamous spragg washer! Last time I replaced the "O" rings one washer spragged the length of the garage, never to be seen again!

 

The Rimmer kit is expensive because it's universal and contains every bit for every Stromberg variation. Except the jet for the late GT6 mk3! I realized to late that the kit had the wrong jets.

 

Although Rimmers stock both early and late jets separately, the universal kit comes only with the early jets.

 

To add insult to injury they refused to swap the jets because my jets were part of a kit.

That's useful to know - thanks Doug

 

Gully