SS1 Mixture & Running

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Dave 6726
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SS1 Mixture & Running

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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reliant-reviver
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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?


Philip Andrew.
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philhoward
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SS1 Mixture & Running

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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Dave 6726
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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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philhoward
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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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