Lotus Elan

Re-starting The Tc

PostPost by: type26owner » Sun Feb 06, 2005 2:56 am

The manual states the compression reading should be at least 160 psi with no more then a 20 psi variation.
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PostPost by: Matt7c » Sun Feb 06, 2005 8:32 am

The compression test revealed the following:
Cyl 1 = 180psi
Cyl 2 = 175psi
Cyl 3 = 180psi
Cyl 4 = 180psi
I'm guessing that 180psi isn't 'too much' if the manual states 'at least' 160psi. I think its time for the carb refurb... Actually, I suspect this will just be the cleaning and seal replacement exercise refered to in the manual. Blowing out and reseating the jets will at least confirm there are no blockages.

Just to put this into persepctive, when I say my carbys look in good nick (externally), take a look here:
<a href='http://www.northamptonmotorsport.com/default.asp?id=19' target='_blank'>http://www.northamptonmotorsport.com/default.asp?id=19</a>
The first 2 shots on that page show a really mucky Weber. Mine genuinely look more like the one in the 3rd picture (ie refurbed and finished) with the exception that my brass bits don't gleam!
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PostPost by: type26owner » Sun Feb 06, 2005 2:05 pm

Permission granted to tear away! :D Are all the accelerator pumps working and were you able to get it started though? You are feeding it fresh petrol and not 13 year old stuff correct? :ph34r:

Just because they look grungy does not mean they are broken. Their age is probable cause though.
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PostPost by: Matt7c » Fri Feb 11, 2005 1:12 pm

Sorry I've been quiet for a few days, been a tad off-colour so haven't had chance to spanner the car. No, the accelerator pumps don't seem to work, but yes I am using new petrol. The 13 year old 4-star has been drained and is now on cleaning duties. Thanks for the link to the Weber manual. I think the plan is to remove the carbs again, do a full bench service and re-seal and then try to get her fired up again. Although I could see no evidence of blockages when I was cleaning them, I do think that the internals have gone dry and gotten stuck - hence the accelerator pump not working. I'll report back when they are re-fitted; thanks for your help.
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PostPost by: type26owner » Fri Feb 11, 2005 2:29 pm

IIRC, there's a check valve consisting of a ball bearing and a slug above it to weight it down to allow the accelerator pump to gulp fuel in each of the throats. They are either stuck open or closed but they are stuck for sure. Don't bother taking the carbies off the car to just fix that problem. It's only about twenty minutes effort to pull the covers off and correct that condition. While the top cover is off you can test the accelerator pumps for proper functioning. Just be careful because the round plate holding down the spring on the accelerator pump pistons can pop up out of place. Once those squirt okay you should be able to fire it up okay.

Go to page 14 of the Weber Manual and the check valve is shown there as an exploded assembly. It's on the lefthand side with a screwdriver hovering above it. Piece of cake!
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PostPost by: berni29 » Fri Feb 11, 2005 8:41 pm

Hi

On my carbs that had been sitting both accelerator pumps were jammed. I pulled and wiggled them quite vigourously before they came free. If you are tugging at them and bending over the carb you risk petrol in the face when they let go.

By the way, I read that the valve springs that were compressed while the engine was sitting (if not turned over regularly) will be junk after so many years. Also the piston rings can indent the bores (apparently). My engine sat for 5 years so it is probably true of mine as well. I always turned my other TC engines over when they were sitting. I thought that it was to push the oil around. Obviously there are other benefits as well.

All the best

Berni
Zetec+ 2 under const, also 130S. And another 130S for complete restoration. Previously Racing green +2s with green tints. Yellow +2 and a couple of others, all missed. Great to be back 04/11/2021 although its all starting to get a bit out of control.
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PostPost by: type26owner » Fri Feb 11, 2005 9:00 pm

Also the piston rings can indent the bores (apparently).

Hi Berni,
They don't indent the engine bore but what normally does happen is since two valves are open there is a way for humidty to enter into the cylinder. The rings are cast iron or steel and the pistons are aluminum. When the two metals are close together they can corrode. Not sure if it's galvanic or not. I've got the ASM Corrosion Handbook sitting in front me of but it weighs at least ten pounds and is a pain to navigate through and I'm lazy so I can't say for sure. :rolleyes:

That's why I told Matt to do a compression test. If they are stuck the engine will not have much in the way of compression. He was lucky to have it all be free and come right up to full compression. My engine sat for twenty-five years and it was frozen completely solid from the corrosion of the rings to the cylinders walls and the pistons.
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PostPost by: twincamman » Sat Feb 12, 2005 2:23 am

have you tried new plugs and wires ?? if the plugs were wet [I believe somewhere in this epic struggle] that was reported 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 » Sat Feb 12, 2005 8:21 pm

Epic the struggle may be, but it consists of only a few hours each weekend and the odd evening, which means its dragging on a little, but not consuming my life. Yet.

Progess, of sorts...

Took off the top covers and removed, cleaned and refitted all of the jets. Took the accelerator pumps out, freed the balls, cleaned and returned them. WD40 certainly put in an appearance. Put it all back together and on the first crank it fired for a second or so. An improvement certainly. Then I was able to get it fired quite a few times, but it fizzled out every time. After careful study of what was going on, I can tell you the following:

- it would start only with the choke and zero accelerator.
- it would run only on pots 3 and 4. 1 and 2 were not firing at all.
- once running, 3 and 4 could keep it going for about 6 seconds before fizzling out.
- any attempt to drop the choke caused a fizzle out.
- any attempt to add accelerator caused instant stop.
- accelerator pumps still don't work!

I count this as a progression from not firing at all, so am not frustrated. Yet... <_<
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PostPost by: twincamman » Sat Feb 12, 2005 9:02 pm

have you replaced the 8 rubber 'o' rings between the carbs and block on the spacers? It still sounds like fouled plugs or an intake leak ----do not over tighten the carbs or you will break the ear mountings[ I'm assuming its a Webber head ] --you may go back to a points system until the lump runs and then put the hi tech system back in----I personally don't mind points as the motor is not hard on them -when it runs so sporadicly it suggests a distributor problem to me -----set the static timing and see if #1 is the correct position in the distributor cap and spark the plug by turning the distributor ---then count 1342 -- ed-----
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: berni29 » Sat Feb 12, 2005 9:43 pm

Hi There

I still reckon it's the carbs. If the accelerator jets are not working then doubly so.

Berni
Zetec+ 2 under const, also 130S. And another 130S for complete restoration. Previously Racing green +2s with green tints. Yellow +2 and a couple of others, all missed. Great to be back 04/11/2021 although its all starting to get a bit out of control.
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PostPost by: type26owner » Sun Feb 13, 2005 3:32 am

Bit of a waste of time to try starting the engine if ALL the accelerator pumps are not functioning perfectly. You're in over your head now I'm afraid. Best for you to now seek out some competent help. Hope you can find some. Good luck!
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PostPost by: twincamman » Sun Feb 13, 2005 2:14 pm

try a visual check of the balance on the carb throttle shafts ie that they both open at the same time ---I still am of the opinion that you have destroyed the timing when you added the pointless system and that one of the factors of the timing requirements is not in the correct position--- either cam timing ---crank timing or distributor timing is off --logic says it ran before---carbs - accelerator pump or not it should have been eager to fire ---idle jets don't require accelerator pumps to run at idle -- recheck every step and don't fall into the mental trap of thinking because you did it it was correct--think objectively otherwise -- I give up -------ed
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 » Sun Feb 13, 2005 6:31 pm

After a day spent repeating everything I have already done, I am at a loss. Now she won't fire at all!! :(

The carbs are now off to Northampton Motorsport for a full repair and refurbishment. Bugger! That's the cash I was going to use to get a new canopy. Ho hum... Hopefully when they return, I'll make better progress. I'll let you know.

Just to bring this thread to a close, thank you all for your help. :)
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PostPost by: type26owner » Mon Feb 14, 2005 2:58 pm

Hey Matt,
Don't be discouraged. It will all be worthwhile when you get the car running and get to drive the wonderful little beast. Because the car is so light weight it obeys the physics mostly reserved just for purpose built racecars. It isn't a cheap car though. The expenses will soon pile up. Expect flak from the Mrs. :ph34r:

Not many folks truely understand the Webers. I cringe when reading the stuff posted on the web. Best to ignore that stuff. None of them can pass the cup of brimming water test I'll bet. You know the Webers are tuned properly if you can place a cup on the camcover and run the rpms up to 4000 with the idle speed screw and not spill a drop.

I just spent the weekend installing a new stock exhaust system less the downpipe. My engine now won't pass the test either. Have to enlarge the air bleed holes on #3 & 4 butterflys now. Changing the exhaust back pressure has affected the tune of the Webers. The new muffler is stainless steel and has dampened the crispness of the music. Bummer. It doesn't buzz anymore like an angry bee though.

If you're going to attempt to tune the Webers yourself then you'll need to purchase the best airflow synchronizer. It's the SK type unit from STE. Goto piercemanifolds.com and look in the Weber tools section for a picture of it. A Unisyn is a real piece of junk compared to this tool.
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