Lotus Elan

New S4

PostPost by: pburgess000 » Tue Dec 16, 2003 9:13 pm

I have just bought my third Elan, after a gap of 25 years. It?s a very pretty S4 convertible, in great order apart from one significant problem. The plugs foul up with a vengeance. It?s on Strombergs, which I understand have no adjustment. It starts instantly in cold weather, the choke can be pushed in right away and it drives perfectly immmediately. But when I get stuck in traffic for more than a few minutes, it wants to stall as the plugs foul.

I have convinced myself that it is running too rich and as it can?t be the carbs (can it?) perhaps there is too much fuel pressure. I have checked all the linkages and the choke quadrant does fully free itself when the choke is pushed home, so it?s certainly not that. The car has electronic ignition. I haven?t checked anything else.

If anyone has any ideas where to go from here, I?d be most grateful

Peter Burgess
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PostPost by: patrics » Tue Dec 16, 2003 10:46 pm

Hi Peter, Its must be running very rich to be able to put the choke in straight away. There is plenty to check, making sure that the correct parts are fitted for a start - metering needle, needle valve and air valve return spring then check the float heights and that the dash pots have oil in them. There are plenty of other bits to go wrong but they tend to make things to lean.
I fitted adjustable pistons and needles to mine which I think has to be a good move.
There is or was? a Haynes workshop manual on Strombergs which is well worth getting - ISBN 1 85010 060 8 and ISBN 1 85010 019 5 in the US
Regards
Steve
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PostPost by: type36lotus » Wed Dec 17, 2003 1:09 am

I second the motion on the adjustable needles. I had these on my Esprit (stock with the car). If you go this route (check, the PO may have already) there is a tool which eases making the adjustments. Dave Bean and probably all the others sell them, they are inexpensive and worth it to have. It is two parts one to hold the diaphragm (prevents torn diaphragms) and the other to adjust the needle.

Mike G.
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PostPost by: gjz30075 » Wed Dec 17, 2003 2:26 am

Peter,
If all checks out as mentioned above, check the jet. It could be elongated after years of having the needle go up and down in it. I'm not a Stromberg expert but I think the needle might be spring loaded against the side of the jet, exacerbating the problem. I think the needle needs to be centered in the jet. This larger than normal jet will lead to richer running.

Greg Z.
'72 Sprint on Webers
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PostPost by: dlbarnes1 » Thu Dec 18, 2003 6:07 am

Peter,
As mentioned, the most probable cause for rich running is wear of the metering needle and possible the jet as well. On these carbs, the metering needle is "biased" to be permanently in contact with one side of the jet. Result - wear. Best solution is to replace both, using adjustable metering needle (and needle adjusting tool).
Several needles are available. Standard is B1G (US) & B1Y (nonUS). A B2AR needle has been used and found to produce better all-around performance.
Also, recommend replacing diaphragms, gaskets, and float valves.
David - 72 Sprint DHC
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PostPost by: pburgess000 » Thu Dec 18, 2003 12:05 pm

Thank you, gentleman, for all the helpful advice. It certainly seems like it all pointing at a carb overhaul. Are the spares/overhal kits readily available in the UK?

Peter Burgess :)
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PostPost by: miked » Thu Dec 18, 2003 5:05 pm

Peter,

I live in the North West and have an S4 with stromies. I fould Bert Holdings at Preston to be great. Frienldy advice and all the parts. If you visit, it is a bit time warped but great fot the parts. His prices are lots less than Lotus places.
He supplies the other carb places.

Tel No is 01772 254971

Re: the adjsuable needles, be careful of the side grub srew on the adustable needle as its slot damages easily. Also, lot have chewed up threads.

If you type in the stromberg details and search the net there are a lot of american triumph owner atricles on these carbs. I did it for info, on the temp' compensators and ended up with boat loads of good advice with pictures etc.

regards Mike.
Mike

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PostPost by: patrics » Sun Dec 28, 2003 10:35 am

Hi Peter,
A long time a go I got spares from either
Burlen Services in Bournemouth 01202 824666 www.burlen-services.co.uk
Southern Carburetters & injection 020 8540 2723 www.southerncarbs.co.uk
I still have some bits available which might be of use.
Regards
Steve (Midlands uk)
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