Correcting fast idle

[BDA]

Sorry, other than a PDF for Bosch plugs, that's all the plug stuff I have. I've attached the Bosch document in case anybody is interested. If you use their plugs, it certainly would be.

[EuropaTC]

It seems the throttle spindle connection between the carbs has been tightened with the LH carb not sitting flat against the idle adjustment screw.  I assume I need to just loosen the center concertina like clamps and then retighten holding the throttle against the adjustment screw? 

Yes, but don't rush in to do that just yet, or at least not until you've got an idea of how to balance the carbs. It's not difficult but if this is the first time you've approached the job it is very easy to make matters worse before they get better.  You'll find specialist books on the rebuilding/setting up these carbs but for now the workshop manual has a good section on how to set the system up and it covers what you need to know.

It is certainly possible to balance them with only basic tools, but this is where having a flowmeter such as John posted earlier really comes into it's own. You could be lucky and get it right first time by estimation, but these tools get you exactly right with numbers to confirm that you've got the perfect balance. Well worth it.

Brian

[kiwiokie]

I also own an Alfa Spider with Weber DCOE’s so I already have the correct flow meter just have never worked on a Stromberg before.  They look so simple from the outside with so little to adjust that it makes me about worry what I am missing!

[jbcollier]

Everything you ever wanted to know about Strombergs:

http://www.lotuseuropa.org/LotusForum/index.php?topic=3619.0

[kiwiokie]

Thanks.  Already found and printed the entire post :-)  Replaced the damper oil with Dexron ATF over the weekend.

[kiwiokie]

Not much success so far.  Did fix the LH carb that wasn’t seating against the idle adjustment screw.  Tried in vain to see any timing marks with a strobe light even after highlighting numbers with white paint.  Nothing unique about this process right - attach to #1 plug wire closest to front of car?  Seems hard to believe timing would be that far out?  I guess I will need to start from scratch with static timing and go from there.  Positioning of distributor is not ideal but feeling around I could not find a vacuum port.

[EuropaTC]

Tried in vain to see any timing marks with a strobe light even after highlighting numbers with white paint.  Nothing unique about this process right - attach to #1 plug wire closest to front of car?  Seems hard to believe timing would be that far out?  I guess I will need to start from scratch with static timing and go from there.  Positioning of distributor is not ideal but feeling around I could not find a vacuum port.

That's odd, if it's any consolation I'd be scratching my head at that one as well. Firstly, yes, there's nothing unique about setting up a timing light they just clip on as normal.

Without checking I can't remember how many marks are visible through the viewing aperture but I would have thought at least a couple giving 10deg+ range.  So if you can't see anything after highlighting the lines/numbers then something is very odd.  Even if the previous owner had fitted the UK distributor and used the 9-33deg range then you should have something to see even if your idle speed is well off.

I think the highest mark is 30deg (not sure, check yourself) so if you didn't get anything I suppose in theory the weights could have stuck giving maximum advance & throw you out of range up to 33deg if the static setting is higher than the standard 5deg for your engine.   But looking at the engine bay I can't imagine how that would happen, it looks so well cared for.

I think you're right, we need to go back to static timing. If you're on CB points or the early version of pertronix you can do that from the coil connections with a couple of leads & a bulb without any further dismantling. I don't know how it works with other ignition systems but that's where I'd start from.

Back to spending your money     -  if you don't have one already, get yourself a fibre optic borescope/endoscope thing. You can get them as USB for a laptop or even for your phone these days. They make looking under and inside engines so much simpler than trying to jiggle a mirror & torch.  This sort of thing.....

https://www.ebay.co.uk/itm/1M-2M-USB-Endoscope-Borescope-Snake-Inspection-Camera-Android-Mobile-Phone-UK/223613632821?hash=item3410694135:m:mrP3P5swW4z3oDQf2iXVp1Q

In the past I'd remove the distributor to fit new points simply to see what I was doing, but with one of these you could probably do it in-situ. It certainly makes checking the gaps on CB points very easy.  One of those things you never need until you've had one, and then you find lots of uses for it !

Brian

[kiwiokie]

Thanks Brian.  I have a test light and a borescope so should be able to get this done over the weekend.  I also need to check if the temperature compensator is still in use and if so, disable.  One thing I noticed was after blipping the throttle the idle would drop below 1,000rpm but the engine would stumble badly, shake, complain and almost stall before gathering itself back up and raising the idle to 1,500rpm again where it happily sat.

[BDA]

I agree with Brian. You should see some mark at some time with your strobe light. Static timing is definitely in order. IIRC, static timing should be 5 degrees BTDC.

I'm not an expert with carbs of any kind much less Strombergs, but your description sounds like a mixture problem. I'm thinking it's too rich. Maybe somebody more knowledgeable than I can confirm or correct me.

[jbcollier]

If you are running solid core wires, electromagnetic interference can mess with timing lights.  Also possible your mechanical; advance is seized.

[Bainford]

If you are running solid core wires, electromagnetic interference can mess with timing lights. 

Interesting. I didn't know this. I'll have to keep an eye out.

[jbcollier]

Using resistor spark plugs can solve the problem.

With solid-core wires my timing light's advance function doesn't work very well.

[SENC]

Your timing can't be too far out, or you'd have trouble starting and/or running.  Let it warm up, then advance the timing a bit to see how it idles, then retard it to see how it idles.   Find the best spot you can, then see if you can lower the idle speed a bit.  Keep fiddling until you find the lowest smooth idle you can achieve.   Turn it off and restart - easier or harder restart?  Adjust as necessary.  Advance enough to get some plinking, then back down.  Obviously not as good as actually seeing the timing, but should be in a safe range and good enough for the first round of adjusting the carbs.

Double-check the diaphragms for holes and the pistons for easy movement, and make sure they fall freely and close fully with a click.  Check the butterflies, are they all fully shut with no throttle?  Fully open and parallel with full throttle? Do they close with a click when the throttle is dropped suddenly? Any obvious differences from one to the next?

How are your carburetors attached to the engine, what type of manifold?  The Elan has a Federal version with emissions equipment or Euro version with balance bar - not sure whether the Europa is the same.?  Soft mounted with thackeries/grommets, or hard-mounted?  Appropriate gap between carb and manifold?

Check for vacuum leaks at the manifold and adaptor plates or any take-offs, as well as where the throttle spindles come through the carb body.

Keep going back to timing and throttle screws, looking for a decent idle at 800-1000 rpm.  It will be a bit lumpy with Strombergs, but should hold steady without needing to blip the throttle.  If you can't get there, its time to go further inside the carbs.  If you can, then start checking out where things stand under load and with partial and full throttle.

What needles and pistons are in the carbs?  Are the needles adjustable?  Do the needles show wear?  How about the jets they slip into?  Wear on either/both parts will contribute to richer conditions.  Perhaps the idle mix screws you found open were opened in an attempt to lean things out?  Are the floats correctly set for the right fuel level?  Is the fuel valve working correctly?

[kiwiokie]

Well I was not able to fix the problem but I think I may know what it is.  I tried winding the idle screws in all the way and then started adjusting them out until I could get the engine to idle.  After a few turns it popped right back up to 1900 - 2000 rpm.  I backed down a quarter turn at a time until I was at 1500 but then could not get it to go lower.  To make sure the throttle had returned against the idle screw on the LH carb I gently tweaked the spindle and the engine stumbled and almost died.  Gently wobbling the spindle produced stumbling and erratic idle.  There is definitely play in the LH spindle so it seems I need new bearings and may as well rebuild.  I also checked the static timing and diaphragms which were OK and disabled the temperature compensators.  Also adjusted the gap at the flexible manifold.  Do worn bearings sound like a reasonable diagnosis?

[kiwiokie]

Before I got to this point I tried balancing the carbs using the synchrometer and was able to get them balanced at about 1400rpm but could not get it any lower.  The previous owner sent the engine out for the rebuild but I think he did the carbs himself so I don’t have any details of what needles and pistons are in the carbs.  The car has only done 3000 miles or so since the rebuild was done.