Lotus Elan

Re-starting The Tc

PostPost by: elanman3 » Wed Feb 02, 2005 12:48 pm

Matt,

I can confirm what Martin was saying about the needle valve sticking and overflowing. The same happened with my dellortos. I had fuel coming out into the air intake box that ignited. Luckily I had a fire extinguisher close by and ended up with no damage worth talking about. But what I would say is that even though you've unstuck the needle valve, I'd still recommend that you either overhaul the carb's yourself or have a professional do it for you. The last thing you want is a fire in the engine bay.
If you ever see your car changing colour from blue to flame red/charcoal brown you'll wish you'd done it. I needed a new set of trousers after it happened to me.

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PostPost by: Matt7c » Wed Feb 02, 2005 7:57 pm

Well, I think I was a little premature with my declaration of life a few days ago. Since bursting into life to 10 glorious seconds, she now won't start at all. She does occasionally fire on one cylinder once, but hardly even that. Took a look at the plugs and found that those in 1 and 2 where still shiny silver but thoroughly wet with petrol, while those in 3 and 4 were dry sooty and black as a black thing (brand new plugs 3 days ago).

I'm thinking that the ignition is probably OK after going through the setup in detail again and following the advice Keith left on this thread. Begining to think that the carbys are not performing. Any suggestions on what to try and tweak first, before I take them off again for the full strip down? :huh:
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PostPost by: type26owner » Wed Feb 02, 2005 8:16 pm

Here's an easy way to make sure there is spark going to each plug. Plug the HT leads into four spark plugs which are laying on the camcover and are therefore earthed. Crank it over with the starter motor with the ignition switch on. You should be able to see the spark jump across the four plugs and know for sure if all is okay or not. Not making any assumptions is the best course to take. Much easier and quicker to diagnose the ignition then the induction system. If there is good spark to all the plugs then the next step is to do a compression test. If those two items out of the three basic requirements needed for combustion are good then and only then do you tear into the carbies.

The polarity of the two of the magnets embedded in the reluctor could be reversed for instance.
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PostPost by: Matt7c » Wed Feb 02, 2005 9:54 pm

Thanks for the tips Keith. I had already had the timing light connnected in series with each plug in turn which had convinced me I was getting a spark, but I have just done your check and confirmed that I do have sparks and they are even in the right order! A compression test requires a compression tester that screws in the spark plug hole, right? I don't have such a device, but will have a look around for one. Supposing I get one, what pressure value would I be looking for?

PS: have now ordered a compression gauge for ?11.42 from an Internet tool shop.
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PostPost by: type26owner » Wed Feb 02, 2005 10:45 pm

Matt,
Don't know the value off the top of my head but I'll look for it later when I get home from work. Remember to open the throttles completely when doing the test. If you don't the readings will all be alarmingly low. It's a very common mistake.

but I'll look for it later when I get home from work.
Aahhh cancel that. Remembered on my way home I left my manual over at my parent's house so you'll have to get the info from someone else.
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PostPost by: twincamman » Thu Feb 03, 2005 4:02 am

ok -- if you have spark fuel and timing try adjusting the two rich idle screws 1 and 1/4 turns out from the bottom------the compression on my elan tc is 180 and on the 7 tc 175 ed law
dont close your eyes --you will miss the crash

Editor: On June 12, 2020, Edward Law, AKA TwinCamMan, passed away; his obituary can be read at https://www.friscolanti.com/obituary/edward-law. He will be missed.
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PostPost by: tdafforn » Thu Feb 03, 2005 12:37 pm

My +2130s has simlar figures
1972 +2S130
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PostPost by: type26owner » Thu Feb 03, 2005 2:53 pm

Matt,
A car that sat for 13 years and was not stored properly is going to have at least gum deposits left in the fuel system when the fuel went sour. The carbies undoubtably need cleaning but be careful how it's done. Go buy the proper dunking type cleaner to do the job. When you do this the leather seals on the throttle shafts will be need to be renewed. The leather will have dryed up and the chances of it sealing properly are nearly zero anyway. Since new Webers are now not available but the spares still are your options are limited. You must rebuild yours or find good used units to buy. If you're mechanically gifted then I'd say go for the rebuild option though it gets quite expensive to DIY. Otherwise seek out qualified help by calling the folks at Webcon UK for advice. If there is thick corrosion in the bottoms of the float bowls then in the past they would have be considered destroyed but in light of the fact there are no new Webers being made anymore perhaps that's not the case anymore. Unless of course the metal has crumbled away to the point the structure is damaged like some threads are gone.

Don't buy the Weber leather seals because they are junk. About half of them will have holes from the way they where poorly cutout of the sheet. Make up your own and saturate them with Mink or Neatsfoot Oil. To tell for sure whether or not the leather seals are toast there is a simple test to perform. Good seals will allow the engine idle speed to slow down to around 400 rpm where the engine will stall out as the idle speed screw is slowly back off. If the engine merrily idles along inspite of the idle speed screw being moved then it's doing so on the airleaks. So what you say? Well if enough air is getting sucked in by way of the throttle shafts then it isn't being forced to flow past the first progressive hole so when the throttle shaft gets opened ever so slightly there will be a stumble off idle that cannot be tuned away. Guessing the leather seals are only good for about five years even if the car is seldom driven.
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PostPost by: type26owner » Thu Feb 03, 2005 5:19 pm

If you're mechanically gifted

AND have a well equipped machine shop then go for it.
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PostPost by: Matt7c » Thu Feb 03, 2005 6:57 pm

Thanks again fellas. My pressure gauge was posted today, so that could be a job for the weekend. The pressure test is easily done and will hopefully, hopefully eliminate poor compression as a problem.

The carbs seem in quite good condition. The car itself was dry stored for all that time but actually went into storage in working order - the previous owner stopped using it only 'cos his house burnt down which made him both very busy and very broke. The carbs, amazingly, had no sludge or gunk in them when I opened them up and there is no visible corrosion on either the inside or outside. However, I already know the top seals don't as I had an overflow issue earlier; now resolved.

If the pressure test reveals nothing, I'll try the idle screws as suggested by twincamman. If that gets me nowhere, the carbs will go back on the bench for a strip down and refurb. I'd prefer that than engine rebuilds!
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PostPost by: type26owner » Thu Feb 03, 2005 7:11 pm

Check to see if the accelerator pumps are working. If they do then you can get it to run by continuing to juice it with petrol via the pumps alone. You can check that they are working in situ with a mirror by looking down the throat the of carbie and quickly open the throttles with the engine switched off. You should see it squirt out a stream of fuel directed towards the throttle plates in every throat. If it does not squirt properly on every cylinder them report that back and I'll describe how to possibly fix it.

What flavour of Weber are these? It's last two digits (XX) of the label 40DCOE XX.

BTW, trying to keep the fuel from leaking out using the paper gaskets from under the top cover and the inspection cap for the jets is hopeless. The newer carbies 151/2 have an elastomer gasket which does the trick great with a slight modification. The ones to seal the inspection cap I made up. I posted how to do it here sometime ago so search for it.
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PostPost by: twincamman » Thu Feb 03, 2005 7:14 pm

give some thought to replacing the points or at least cleaning the points up and re gapping them----25 years may have caused some corrosion------i replaced the coil on mine after it had been stored for many years -- it had many of the same problems you describe and it ran a treat -- I used a big blue Bosch coil instead of a Lucas--- ed law
dont close your eyes --you will miss the crash

Editor: On June 12, 2020, Edward Law, AKA TwinCamMan, passed away; his obituary can be read at https://www.friscolanti.com/obituary/edward-law. He will be missed.
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PostPost by: Matt7c » Fri Feb 04, 2005 8:16 am

Hi Ed, the TC is now a points-free zone after I upgraded to the Aldon Ignitor, also with a new Lucas Gold coil. I'm pretty sure it all works and is statically timed as I've been through it all a few times.

Keith, thanks for the tip about the accelerator pumps, I'll try that on Saturday afternoon when I can next get my hands dirty. A few posts ago, you mentioned about air getting in, and I think that may be a factor, IF the screws for the idle jet and mixture need to be air tight. I just took a look at their rubber seals and they are shot! Forgive my lack of understanding, but is that a problem?

Matt
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PostPost by: type26owner » Fri Feb 04, 2005 2:42 pm

Yes, airleaks are bad. Small ones are not the problem at the moment but any that are large will cause that cylinder to not fire. For now just goober some grease over the suspected leaking o-rings to seal them temporarily and get the engine to fire up and run smoothly. Smear lots of grease over the ends of the throttle shafts to seal up the leather shaft seals also. You can fix those small problems later. Don't lose focus which is just to get the engine to run first.

The compression test is necessary because there is a good chance the piston rings are frozen from corrosion or the exhaust valves might be burnt on #1 & 2 cylinders. Another fault condition which most people don't consider is at least two valves sat with their springs fully compressed for 13 years. One intake and one exhaust. Springs when highly stressed will relax slowly over time. Get it running for now but for sure you're looking at the very least having to remove the head to put a new set of valve springs in it. If you don't it will run like crap at high rpms and you'll never figure out why it's always missing or if not fully missing then it lays over and does not pull hard. For this reason our BRM race engine has the crankshaft rotated to another position at least once a month to slowdown the degradation process.

That's not so bad. Had dinner with Dan Davis the editor of VictoryLane magazine about ten years and he led into the a discussion about valve springs by asking me to guess how much a set cost for a Ford DXF engine. I guessed right on the nose at $2400. He found out the hard way those engines have to be rotated weekly and the springs are toast after one year even if it does not get fired up once. Vintage F1 cars cost $500 per lap to operate I'm reliably told as of ten years ago. Little wonder it's done with pneumatics now.

Here's the original Weber manual but the part you want to pay particular attention to is the Running Fault section which starts on page 27.
<a href='http://www.lotuselan.net/uploads/weber.pdf' target='_blank'>http://www.lotuselan.net/uploads/weber.pdf</a>
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PostPost by: type26owner » Sat Feb 05, 2005 6:01 pm

Matt,
Keep in mind there are some glaring omissions from the Running Fault list. Like checking for the leather seals on the throttle shafts having shrivelled and become stone hard. Also the fact the process to correctly phase the throttle plates relative to the first progressive hole on the micron level would be so prohibitively expensive for the OEM to do on each engine likely it was not done at all. Why they left mentioning the compression test off their list is a bit of a mystery though.
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