Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: kiwiokie on Friday,May 08, 2020, 06:55:33 PM
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Hi folks, I have not posted in ages - just been enjoying some trouble-free motoring. A couple of things I had meant to look into were difficulty in starting when the engine is cold (requires 3 or 4 long spurts of cranking even with choke pulled out) and a fast idle (1800-2000 rpm) even when the car is warmed up and the choke fully in.
The car was restored by the previous owner and I have not had any experience with British cars before so I have been reluctant to dive into it. The car in question is a ‘73 Europa TCS with Stromberg and I understand it is running a Pertronix ignition and coil. Spark plug wires look good. Car has only done less than 10,000 miles since rebuild.
I started by removing the spark plugs and found they were Champion RN9YC’s whereas the owners manual recommends N7Y’s and I had read on this site that NGK BPR6ES plugs were preferred. The plugs looked like the cylinders were running lean. I bought a set, gapped to 0.025” and installed and it was even more difficult to start. I then read on the Petronix site that they suggest increasing the gap by 0.005” which I did. Doing more reading and inspection of the carbs I found the idle trimming adjustment screws were wide open so I screwed these in and with a combination of the two changes it started and seemed to run better.
I was not sure if the tach was reading accurately so using an external tach I verified that the idle is indeed 1800-2000 rpm when warmed up. There is a 1mm gap on the choke screw so I can see it is not engaged. Before I go any further I just wanted to get some advice and make sure I was planning the correct steps.
From what I have read to do a thorough set up I need to do the following:
1. Check the valve clearances
2. Check the static timing of 5 BTDC
3. Check the timing at 3000 rpm of not more than 38 BTDC
4. Only then adjust the idle speed of the carbs
I guess the issue could also be stuck mechanical advance on the distributor so maybe that should be step 0? I have a Colortune test kit but from what I have read there is no mixture adjustment on these carbs as standard unless adjustable needles have been installed which I am unsure about.
Any help would be appreciated. Cheers, John
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First, we are always glad to welcome another member! Congratulations on choosing a car that's pleasures are equally matched by it fascinating design.
It's an unknown car to you so it is a good idea to give it a thorough going over. BUT, you could start by simply turning the idle speed down. First check that there is slack in the throttle cable when it is released. If so, take careful note of the idle speed screw's position on each carb. To start, turn each screw EXACTLY one 1/2 turn. Help? Good. If not, you may have other issues with the carbs/synchronizing/manifolding.
We can walk you through a complete tune-up and/or carb overhaul as needed. The first thing I would recommend is the purchase of a good carb synchronizer. My preference is for this type:
https://www.ebay.com/itm/173869307112
as it does not affect the idle when you use it. There are various angle adapters which are handy in the tight quarters of the Europa engine bay. Weber, Dellorto, Porsche and air cooled VW shops carry them.
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:Welcome: kiwiokie!
I love the color ;D!!
+1 on JB's recommendation, especially the flow meter. They are MUCH better than the ubiquitous Unisyn.
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Hi John,
"trouble free motoring" ?? Are you sure this is a Lotus you're talking about ? :)
Ok, joking aside let me start by saying I know very little about Strombergs and the last car I had with them was well over 20yrs ago so you'll know to take my comments as "guesses" rather than super accurate knowledge.
First the plugs - the N9 is a hotter plug than the N7 series and the N7 is better for an engine where you're revving harder. I'd expect the N7 to soot up quicker than the N9 if you do a lot of commuting, low speed stuff, etc. Referring to Miles Wilkins' book, he says the N9 was standard with your engine & the N7 for "sustained high speeds". However he later adds that N7's can also be used if you have electronic ignition modules fitted which give a higher voltage/hotter spark.
Next, John's suggestion of checking the idle screw position and slack in the cable are the first port of call, it may be as simple as that !
If that doesn't work one thing you can do without any dismantling is to check the timing at idle. There's a lot of detail in Miles Wilkins book but in case you don't have it, here is the data for the Federal Stromberg, 41225A distributor with the vacuum retard fitted;
Below 2000rpm, 5deg, static timing & no advance
2500rpm : 7.5
3000rpm : 9.5
3500rpm : 12.0
4000rpm : 14.3
4500rpm : 16.5
5000rpm : 19.0 max advance
Some of those numbers look academic to me, I couldn't tell that sort of accuracy from a timing light on the engine ! But it should give you an idea where you are.
If the previous owner had removed the vac. retard and/or fitted the UK 40953 distributor, the numbers will be a lot different. NB - this shouldn't be on your car as exported, but Lotus owners are known to fiddle with stuff......
Below 1000rpm, 9deg, static timing & no advance
1000rpm : 14.6
1500rpm : 19.5
2000rpm : 25.0
2500rpm : 25.8
3000rpm : 26.8
3500rpm : 27.6
4000rpm : 28.5
4500rpm : 29.5
5000rpm : 30.5
5500rpm : 31.5
6000rpm : 32.0
6500rpm : 33.0 max advance
Final comment from Miles' book; he explains the development of the Federal Strombergs and the differences from the UK versions. The advance curves were modified to give a quicker warm up and pass the emission tests. The downside was that 19 deg isn't enough to get the best from the engine and he does mention having seen examples where the static timing has been raised to 14-15 deg to give a max 29 deg advance on the 41225A and get it closer to the UK spec engine.
In conclusion, assuming all parts are working properly (and they should be, that engine looks amazing) then my checks would be in order of least work ;)
Ignition is easy - check what you've got compared with those ranges above - timing light and running engine is all you need. Have a look at the distributor and see if the vac retard has been removed or the distributor changed for the UK spec, you'll need a mirror (old school) or ideally one of those USB fibre optic leads going to a laptop which makes it easy to read numbers.
This should give you an idea if the timing is right/wrong/modified. Also if it doesn't change with revs, the advance could be sticking as you mention.
Next would be carbs and if we've still got a high idle after checking the adjuster, then move to see if the linkage is allowing both carbs to close properly.
After that we're into more work.
I'm very hazy on the mechanics of this with your carbs but my guess would be to remove the air filter box and check the air flows through both. which would show if they are balanced properly on the idle adjustment and linkage. The flowmeter like John suggests is ideal for this. As an outside chance maybe look for air leaks from the manifolds, air box, etc.
Valve clearances timing would be my last check, I'd do the cam timings first but I'd concentrate on ignition/fuel then cams.
Finally, I'm going to spend your money (I'm good at spending other folks. money :) ). Firstly I'd recommend Miles Wilkins book on the TC engine. It's mostly about rebuilds but has loads of technical details on all the variants and also explains where the official period Manual has errors. Well worth the money.
If you have to tinker with carbs then a device to measure air flow is very helpful. Colortunes are good (I have them) but air flow shows how the individual carbs are passing fuel/air into the engine and makes them very easy to balance. I have the one in John's link and it's worth it's weight in gold !
Brian
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First, I don't have a Europa but an Elan with Strombergs, so take this with a grain of salt - but I'm surprised at the low static advance on timing. My bet is the throttle was increased because the car wouldn't hold idle at that timing (plus either a lean or rich condition). I'd advance a bit and see where that lets you drop the idle.
Depending on what you find, you'll have get some ideas on rich or lean. Have you filled your dampers? Checked your diaphragms? Checked your floats? The good news is that these are quite simple carbs to work on. Adjustment is limited (primarily through needle/jet change) so not much to go wrong.
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Thanks guys, I will check the timing. I expect SENC is right that the idle was increased as it would not hold sub-1,000 rpm. I have that model synchronizer so will check the carb balance too. Sounds like I should go back to the RN9YC’s since I mostly use it for short commutes?
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The NGK 6 should be similar to the Champion 9, I think I recall.
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These charts might be helpful. I've been using NGK and like them.
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Thanks for posting the comparison charts BDA, I hadn't seen the comparison between manufacturers grades. I knew some of the numbering but not a breakdown as good as that.
Now all I need to do is to copy them and next time I'm tinkering with plug grades, remember where I saved them !
Brian
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Interesting, I did not know the heat ranges differed by manufacturer. Thanks for the charts!
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If you're interested in comparing heat ranges, I'd advise that you try and find others that might or might not corroborate the one I posted. I don't remember where I got it. It's not that I don't believe it but finding another source that agrees (or maybe a more authoritative source) is a good practice. You can search for something like spark plug heat range comparison.
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I turned each idle screw CCW half a turn and the idle dropped a little. I gave it a another 1/4 turn and was able to get the idle down to 1500 rpm but it is a little rough. One thing I noticed was the LH idle screw was loose as I could turn it with my fingers despite there being a spring to tighten against. I pulled gently on the throttle spindle and it moved back against the idle screw and the revs dropped further. 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? I went to check the timing but the timing marks are so faded I could not read anything. Painted them white, will scrub off excess, then hopefully I can see where I am at.
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If you haven't found it yet google buckeye triumph stromberg and you'll find a great resource. It is worth reading through the disassembly, reassembly and setup even if you'd never do that yourself (why not?) as it will be helpful in how everything works together.
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Yup, you can just loosen the connecting link. Tighten it after you sync the carbs at idle.
One carb has a manifold vacuum outlet underneath the throttles. Make sure that is plugged.
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These charts might be helpful. I've been using NGK and like them.
BDA, do you have a .pdf version of those charts you could post?
t
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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.
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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
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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!
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Everything you ever wanted to know about Strombergs:
http://www.lotuseuropa.org/LotusForum/index.php?topic=3619.0
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Thanks. Already found and printed the entire post :-) Replaced the damper oil with Dexron ATF over the weekend.
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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.
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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 (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
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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.
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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.
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If you are running solid core wires, electromagnetic interference can mess with timing lights. Also possible your mechanical; advance is seized.
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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.
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Using resistor spark plugs can solve the problem.
With solid-core wires my timing light's advance function doesn't work very well.
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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?
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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?
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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.
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Grab each spindle and try to move in back and forth perpendicular to the axis of rotation. There should be virtually no movement.
There are no bearings. Often just replacing the shafts is sufficient. Details can be found in the post previously mentioned.
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I think the needles are labeled at the top where it is screwed into the piston. Somewhere the standard needles are listed and you can see if you have the correct needles.
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If there's play in the spindle/butterfly then could you have an air leak at that point ? I've not had enough experience with strombergs to know if what you've described is down to wear'n'tear or adjustment, but if you do have an air leak then that could give an increased idle.
Brian
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Grab each spindle and try to move in back and forth perpendicular to the axis of rotation. There should be virtually no movement.
There are no bearings. Often just replacing the shafts is sufficient. Details can be found in the post previously mentioned.
There is clear movement on the left hand carb spindle. Moving it while the engine was running impacted the idle immediately.
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Time for a complete overhaul. The needles and needle jets wear as well. Myself, I would also fit adjustable dashpots from a TR6 or TR7.
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Does anyone in North America offer a rebuild service? I have read the Buckeye complete rebuild pages and it does not seem too complicated but I am closing in on the finish line of a 5-year project car and really don’t want to tackle something else right now.
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http://joecurto.com/
He will do them for you.
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Thank you. This is such a great forum!
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Picked up some lotus service bulletins on the Strombergs. I posted them on lotuselan.net, but thought they may help others here, too, so wanted to share a link.
https://lotuselan.net/forums/viewtopic.php?f=40&t=41122&start=39
topics include jet height, converting to air valves with adjustable needles, and spec clarification
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A great source of all kinds of information, including technical bulletins, is http://lotus-europa.com/manuals/
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Thanks BDA, great resource page!
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Finally got time away from other car projects to spend time with Lilly the Lotus. Pulled the carbs and sent them to Apple Hydraulics for new throttle shaft bushings. Unfortunately they refused to work on them as they were too clean and looked freshly rebuilt and I had not separated the throttle bodies. Rather than wait to talk to me they left a VM and then returned them via UPS. Most ridiculous experience I have had with any service I have used on any car. I will now give Joe Curto a try. Maybe I need to lather them with some greasy road grime first!
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That's really strange! Good luck with Joe!
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They are just sh*ting you. They didn't want/couldn't do the work and made up some garbage excuse. Never heard a bad word about Joe, good choice.