SS1 Mixture & Running

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Dave 6726
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Post by Dave 6726 » Mon Mar 19, 2018 4:17 pm

Gents -
SS1 1600 Weber carb.
Two items together here as I've no idea if they're connected, but any constructive thoughts greatly appreciated.

1. Decided to replace spark plugs, not for any reason particularly, other than they had done about 15k miles without being looked at; always worked well AFAICS. When removed they were covered with dry soot, though not excessive/fluffy. Exhaust tailpipe is black/sooty, rather than grey. To me, all indicate permanently rich mixture, but it runs well, returns average 38mpg. Over the year, return journeys lengths are usually 15 - 50miles. And I hesitate to do anything under the 'If it ain't broke, don't fix it' rule.
First two journeys on new plugs were 10 and 60 miles. Pic: Left is an old plug; right is new after. Q: Should I tweak the mixture?

2. After 10m trip on the new plugs, car sat for a month. Then when trying to start, after initial churning without pressing gas twice as usual to set choke, when I did press gas pedal twice and it started, it was appallingly rough and hunting like mad. Same effect two weeks later, and since. I have to hold gas at 1500 rpm, firing very rough; if I ease off, it stalls.
After two or three minutes holding at 1500-ish, it starts to warm up and as it warms it becomes smoother and runs at a normal c800rpm.
Never had this starting problem before, so assume I must have 'broken' the choke mechanism in some way when trying to start from cold.
Can anybody please suggest what I might have done, and what the cure might be?

MTIA
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Terry Rickard
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Post by Terry Rickard » Mon Mar 19, 2018 4:24 pm

Could be that HT leads are breaking down giving low KV when cold.
First and simplest thing is to fit a set of quality HT leads befor doing anything else.



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Post by reliant-reviver » Mon Mar 19, 2018 4:59 pm

Is the car parked inside or outside?

What carburettor is it?


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Post by philhoward » Mon Mar 19, 2018 5:21 pm

First thought, assuming the 32DFT, is the plastic arm activating the fast idle has snapped off - but it could be a number of different things.


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Post by Dave 6726 » Mon Mar 19, 2018 6:42 pm

Thanks for the starters, gents. I'm an absolute iggy about carbs, unless they're nice basic SUs or Stroms. I've looked in the bible and couldn't believe how complex it was. Will leave it now till tomorrow when I can get at it again.
Terry: Point taken and I'll see if I can see any fireworks when starting.
RR: It's kept inside, but still gets v. cold during this weather. Which Weber it is, I'll look tomorrow. The twin vents look slightly different sizes from a photo, but I'll check and see if I can see a model no.
Phil: If it's the arm with the adjustable pin, which goes into the cam inside the housing, I seem to remember it was OK and metal.
Checks tomorrow, but thanks all for today.



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Post by philhoward » Mon Mar 19, 2018 7:16 pm

It’s the cam inside I was thinking of.


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Post by reliant-reviver » Mon Mar 19, 2018 7:39 pm

Normally in a pile at the bottom of the housing!

Weber don't list the part unfortunately, it comes only as the whole main auto choke assembly.


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Post by Dave 6726 » Wed May 09, 2018 9:18 pm

It's unbelievable how long it's taken me to get back to this, but with other all sorts......
Perhaps as it's an Italian job, the cam is metal and in good working fettle, Phil.
Anyway it's a DFT 4B 32/34 and with some warmer weather, reading the Bible many times, and fiddling on, I think I've discovered that the problem was that the choke flaps were out of adjustment, being TOTALLY closed at start-up (instead of 5.5mm, or some-such, open). I nearly went the whole hog and bought a manual choke conversion, but it seemed such a pity to let all that brain-numbing technology go to waste.
Anyway, by dint of some fiddling and riving the bi-metallic strip housing right over one way, I temporarily got it running almost like normal. Tick-over wasn't as fast as it should be, but that's next job, next week, when I shall attempt to set the thing according to the Bible.



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Post by Alan SS1 » Thu May 10, 2018 12:56 pm

Dave 6726 wrote:
Wed May 09, 2018 9:18 pm
It's unbelievable how long it's taken me to get back to this, but with other all sorts......
Perhaps as it's an Italian job, the cam is metal and in good working fettle, Phil.
Anyway it's a DFT 4B 32/34 and with some warmer weather, reading the Bible many times, and fiddling on, I think I've discovered that the problem was that the choke flaps were out of adjustment, being TOTALLY closed at start-up (instead of 5.5mm, or some-such, open). I nearly went the whole hog and bought a manual choke conversion, but it seemed such a pity to let all that brain-numbing technology go to waste.
Anyway, by dint of some fiddling and riving the bi-metallic strip housing right over one way, I temporarily got it running almost like normal. Tick-over wasn't as fast as it should be, but that's next job, next week, when I shall attempt to set the thing according to the Bible.
I 'thought' INTERNAL snail cam was only ever plastic (unless previously repaired with araldite/ cold pour two pack resin) ?

I had a simialr issue teh day I was heading from ABZ to Orkney via Inverness!! :cry:

but got it going and then tried to 'not stop' :shock: got to Orkney and removed all the bits of plastic and kept in plastic bag until repaired with araldite / MiG wire etc . . . .


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Dave 6726
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Post by Dave 6726 » Fri May 11, 2018 3:58 pm

It was just that it looks, feels and sounds like metal ( so it must be a duck..... :lol: )
Next time I'm in amongst, I'll check further, but it's not broken anyway (yet), so I'm not worried there.

A side issue I have thought of, which the Bible doesn't mention: when replacing the bi-metal strip housing, there are two index marks to line up. On the body and either side of the index are other marks designated Rich and Weak, but I can't find anywhere where it tells one what these positions are for and where they come into the adjustment procedure.



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Post by Alan SS1 » Mon May 14, 2018 12:40 pm

I've just used the description as a guide, if you think it could do with a bit more choke for longer cos you live in colder climes , set it at rich; itjust takes longer to drop off each of the steps on the plastic cam :-)

not sure it makes any ACTUAL odds , just makes you feel better ? ? ? :wink:


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Post by Dave 6726 » Mon May 14, 2018 8:50 pm

Thanks for that, Alan - I'll give it a go and see what happens.



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Post by Dave 6726 » Mon May 21, 2018 12:49 pm

At long last, found some time to get back to it..........
Of course, I knew you guys would be right: the fast idle cam IS plastic and was fine until an exploratory poke around with a small screwdriver. It broke from around its spindle and the bit disappeared into thin air. (It wasn't on the floor , so it must be somewhere under the bonnet, on a chassis rail....who knows?)
So I've ordered bits for a manual choke and that's going to have to do.
Back to take the HT off and put the ragtop on, and wait..... :roll:



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