Crypton Synchro Check Instructions

[v8s4me]

Has anyone got the instruction sheet for one of these?



Essentially, what I need to know is, when the engine is running, should the needle be steady or fluctuating between two numbers? I'm trying to tune a pair of DCOE's and seem to have both results on the same carb/different inlets, even with the mixture screws set the same. Turning the mixture screws doesn't have any effect ie the steady one stays steady and the oscillating continues to flap about.

Any suggestions?

Thanks in advance

[v8s4me]

the other tim said:

I'm pretty sure I have one of those still in it's box in my pile of accumulated toot, ....

Thanks Tim, no rush. You might be pleasantly surprised what these are selling for on eBay at the moment.

the other tim said:

...
Just a thought but with a pair of side draughts you are measuring undamped pulses whereas Sus or Stromberg's usually share at least two inlets often with a balance tube between them so should give a smoother signal....

True, but why would I be seeing an osciating reading on one barrel and a smooth reading of the other barrel on the same carb?

Confused

Does anyone have any tips on how to set up the balance linkage between the two carbs for the initial set-up of the mixture screws?

[v8s4me]

RCK974X said:

...Is it the one connected to the brake servo (bigger volume will tend to smooth out the pulses, even with a valve) ...

Yes it is. That explains that then. Thank you.

RCK974X said:

....Oh, and from you photo, that seal isn't original - they had a rubber cone to allow for different carb sizes.

I think that must have perished and fallen off some time ago. This has a home-made rubber seal; it works OK but it is a bit hard, meaning the gauge has to be held onto the carb quite firmly, adding to the vibration. I'm looking out for some closed cell foam to make something more suitable.

Thanks for your help.

[v8s4me]

RCK974X said:

...If you ever see a cheap one, the old Gunson's Colortune did actually work for mixture settings...

I've still got one of those as well! I used that to set the mixture screws on each cylinder. That got the whole thing ticking over nice and smoothly.Then I used the Synchro and got the strange readings.

The issue is, it is dying when the throttle is opened sharply. We've already gone up a size on the idle jet, which did improve things a bit, but the problem is still there. We can always go up another size on the idle jet but I want to rule out any issues with the way the linkage is set up first.

[v8s4me]

V6Pushfit said:

This is worth its weight in brain cells and buggeration:

http://www.amazon.com/Weber-Carburetors-Owners-Wor...

I bought one of these but it doesn't offer anything not already available on the Web. There is just one section on the DCOE and in that a few brief paragraphs on tuning. There is much much more available on the net so save your money and get Googling.

Andy - thanks for your help.

Update - fitting larger idle jets and re-balancing has helped, and the mixture screws are where that should be with a nice blue flame in the Colortune. But it still coughs and stalls when the throttle is snapped open. The timing is advancing as it should so, is the next step (a) larger idle jet, which will be F6 or (b) a larger pump jet? It is currently fitted with 40 so the next size up would be 45. (1700 X-Flow).

Any suggestions?

[v8s4me]

I appreciate that, although with postage it was £10, or the cost of two pump jets, so I offer the comment only as information to any one else considering one of these manuals and not as criticism.

If you found yours helpful, then great.

[v8s4me]

Cerberus90 said:

...Does it rev ok when you build the revs up slowly? (eliminating the pump jets)...

It does, and the Colortune indicates the mixture is staying on the right side of rich as the revs increase. This is why I'm thinking the next step should be the pump jets because, if I understand the process correctly, this is what will give the additional squirt of petrol when the throttle is snapped open. Clearly too big a squirt would probably produce a similar splutter.

With 55/f8 idle jets the mixture screws had to be turned out more than 2 1/2 turns. Fitting 55/f9 improved the idle mixture significantly and now the idle screws are 1 1/2 turns out (+/- 1/8), so that's why I'm thinking we are about right on the idle jet now.

[v8s4me]

RCK974X said:

From your description

1) engine is fine throttle opened slowly
2) stumbles/stalls on quick opening....

Correct.

RCK974X said:

...NB. Colortune should show a momentary yellow (rich) when throttle opened quickly...

It does.

RCK974X said:

....I'd go for larger pump jet(s) first......May be worth doing a web trawl to see if anyone has posted their jets sizes/cal on a similar engine ?...

Thanks for the tip.

[v8s4me]

RCK974X said:

....it could also be the jets are too LARGE ... if so, engine may flood and stall.

I don't think that's as likely as too small, but it's possible......

I had thought of that but as it spits back on rapid opening, and there's no excessive smell of petrol and nothing dripping out of the trumpets, I'm more inclined to think, for the moment anyway, that it's too lean.

Hopefully the next size larger pump jet will make the difference, if not it will probably be a case of re-tracing steps and trying a different combination.

[v8s4me]

We finally got it running smoothly and picking up quickly by setting the mixture screws slightly rich and sorting out the linkage. It may still need larger pump jets, but until it can be run on the road there is no point in further tweaking.

The master cylinder needs replacing; it looks like a TR6 unit. Is it? (It's a 1700M - from 1976).

Presumably all the brake line fittings are UNF?

[v8s4me]

Cerberus90 said:

Pretty sure the Cortina MC, which is what's on the later Taimars/3000Ms (with the push in resevoir as opposed to the screw in one on the early triumph MC) uses metric pipe connections as ours on the Taimar has the little notches in the unions to denote metric thread...

On this one the reservoir is held on with 4 screws, 1 at each corner. So does that mean it is a TR5/6 one then? If the fittings are in good order we'll re-use these with new pipes, so that will avoid any chance of mixing up UNF and metric. I didn't notice any notches in the unions though so we'll have some UNF fittings on hand as a back up.

[v8s4me]

It looks like the one in the photo. Many thanks.