Lotus Elan

Poor cold starting ..Incorrect Distributor on Stromberg head

PostPost by: 8bit-ash » Tue Jun 23, 2015 9:48 am

Hi,

My elan plus 2 has been off the road for a while for some brake and suspension overhauling. Its now back together again and I forgot what a bugger it is to start from cold. Just the slightest squirt of easy start and it fires straight up though. and as soon as its warm it starts very easy.
Trying to combine two Q's into one thread here I guess.
Firstly what could be the cause of this? Secondly I have a webber Distributor installed and not the 40953. Is this likely to cause any issues.

I've fitted a bulb priming pump just after the mechanical pump as I was finding the fuel draining back from the carbs. This seems to have helped a bit but its still very hard to start without a dreaded little squirt of easy start which is always so tempting.
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PostPost by: rgh0 » Tue Jun 23, 2015 9:53 am

Strombergs usually need some choke when starting from cold - are the choke fuel metering units connected and working ?

Provided the idle advance setting is in the 10 crank degrees range then the dizzy should not be affecting starting.

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PostPost by: Chancer » Tue Jun 23, 2015 12:35 pm

Easi start is the same slippery slope as drugs, the engine quickly becomes addicted and eventually wont start without it even if you find and cure the original fault.

More true of diesels to be fair as a petrol engine will still start even when the compressions are down.

+ 1 re the choke mechanisms and also check if the correct ballasted coil is fitted and recieving 12v on cranking.

If you dont have a ballasted coil then the fitment of one and the resistance, solenoid etc may resolve the problem.
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PostPost by: 8bit-ash » Tue Jun 23, 2015 1:14 pm

thanks for the replys. I know re:easy start. i'm trying not to use it but its so tempting. I'll all mentioned at the weekend.
Is it worth searching out the correct distributor or is the difference between them minimal?
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PostPost by: rgh0 » Tue Jun 23, 2015 1:57 pm

The Strombergs need more maximum advance and a different shaped curve for best top end power thus the different distributor number. You should be able to get your dizzy re-curved to the original non emissions Stromberg curve if you have a decent ignition specialist locally

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PostPost by: RogerFrench » Tue Jun 23, 2015 5:09 pm

The wrong distributor won't be a factor in poor starting as long as it's properly timed and you're getting a good spark.
Strombergs do need choke first thing, and the standard choke operation is a bit of a lash-up. A lot of people have the choke operational on one carb only and for most it seems to work.
There's a whole lot of information on Strombergs on the 'net, largely due to them being much used on Triumphs (who started the whole Z-S deal) and MGBs and the like. They do respond to a good cleaning and overhaul, or at least, those on my Europa TC did!
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PostPost by: Galwaylotus » Tue Jun 23, 2015 5:14 pm

The distributor specification should make no difference to starting, only the static advance. There is an optimum advance for starting an engine another for best idle and another for full power. With a traditional points and condenser and mechanical advance final setup is usually a bit of a compromise. With electronic ignition control the optimum advance can be dialled in for each condition.
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PostPost by: tbsmith » Wed Jun 24, 2015 5:09 pm

If your car runs well once it starts, I'd suspect carb issues instead of electrical. I have (had?) a similar problem with my Sprint (Stromberg carbs) for several years. Mine would start fine as long as it had run some time in the last two weeks or so. After that no amount of cranking would get it to start (with or without choke), but give it a short squirt of starting fluid and it started right up and ran fine. So I put in a primer bulb which didn't help, nor did the electric fuel pump which came next.

I've heard that a lack of damper oil can make starting difficult, but not sure why since it only serves to enrich the mixture during acceleration. I would always add oil if they were low but that didn't help either. Anyway, last week I finally decided to rebuild the carbs.

After the rebuild, I let the electric pump run for 10 seconds or so to fill the bowls, and I got the shock of my life when it started instantly and with no choke! I mean in less than one second of cranking. Here are the things I fixed/adjusted during the rebuild (note I didn't buy a kit since I have a good selection of o-rings):

    Cleaned out the choke plate progression holes (two of them were blocked)
    Reinstalled the choke plate the correct way around (it can be - and was - installed backwards)
    Replaced the small orings inside the piston (above the needle valve) and re adjusted the needle
    Adjusted the temperature compensators (they were bent permanently closed)
    Cleaned all passageways, cleaned venturi (gummy residue near the manifold)
    Checked float level, float valve - both ok
    checked bypass valve - ok
    Finally, reinstalled the diaphragm covers the correct way (they were rotated 90 deg).
I'm now waiting two weeks to see if it will restart okay. If so, then one of the above things fixed it. My guess is that it was either the damper orings, reversed choke plate, or incorrectly installed diaphragm covers, or possibly a combination thereof.

Hope this helps,
Tom

PS I found some good rebuilding instructions on a Triumph TR6 web site (Google should find it)
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PostPost by: Galwaylotus » Thu Jun 25, 2015 9:21 am

I second the recommendation on carburetor rebuilding. I rebuilt my Webers and the difference is nothing short of amazing. :D
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