Lotus Elan

Elan + 2 DRIVING ME CRAZY

PostPost by: Elvis » Thu Nov 08, 2007 2:45 pm

Help !

I have a 1971 S130, 2 previous owners, 38000 miles, so far so good.
Problem is I cannot get the engine to run smoothly.
I have changed the plugs, points, condenser, coil, leads, fuel pipes, checked the timing, compresion and balanced the carbs.
As soon as you put new plugs in it runs fine for about 2 miles then misfires on acceleration and looses power. Clean the plugs, no difference, put new plugs in runs fine for a while. I have had 2 garages look at the problem now, everything checks out, they put new plugs in, it runs fine, I drive it home things are looking rosey, come back to it the next day and yes youve guessed it, it`s running like a bag of spanners again.
Any help is much appriciated
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PostPost by: jayrz » Thu Nov 08, 2007 3:12 pm

Check to see if your floats have partially filled with fuel and therefore not holding proper fuel level.

My 69 S4 has done this twice now in 7 years, allways runs like a champ once corrected.

Jay
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PostPost by: elansprint » Thu Nov 08, 2007 5:27 pm

Elvis check the needle valves in the float chamber my mates excel used to run fine get 2 miles down the road & it ran like a bag of nails only found the problem by dismantling the carbs on the side of the road to find dry float chambers. Valves were worn & sticking although they operated OK manually.

Ian
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PostPost by: Elvis » Thu Nov 08, 2007 10:03 pm

Ian /Jay

Thanks I will try what you suggest this weekend and let you know how I get on

Elvis
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PostPost by: cliveyboy » Fri Nov 09, 2007 3:00 pm

Elvis
What are the plugs like when you take them out. Are they fouled up (soot or wet)
Are you using grade 7 plugs. If so go for a set of NGK BP6ES.
These are slightly hotter and stay cleaner.
I have had similar problems and changing the plugs makes it run better.
If you combine this with not venting the engine breather into the air box it really does make a difference.

Clive
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PostPost by: Elanintheforest » Fri Nov 09, 2007 4:09 pm

A lot of folks said you were still alive Elvis, but I just didn't believe them until now. :D

Something to eliminate. Blank off the two vacuum takeoff points from nos 1 and 4 inlet manifold....you won't have any pop-up lights or servo, but try running the engine for a while like that to see if it runs clean. Air leaks from either (or both) vacuum systems can wreek havoc, and it may not be something that is too obvious to the average garage.

Also check the brake fluid level...if it's low and you don't know why, it could be the servo breaking down...which may result in the fluid being sucked into the engine, burnt and producing smoke when you drive (and oiling up no. 4 plug).
Mark
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PostPost by: memini55 » Fri Nov 09, 2007 5:06 pm

I would also suggest the plug change as Clive has said and second the NKG plugs. Our +2 would run as you discribed and we were using Champion N7's and would loose one cylinder after very little usage. Made the switch to the NGK's and have never had an issue.

Good luck
Mark
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PostPost by: twincamman » Fri Nov 09, 2007 5:46 pm

try changing your air filter ---ed
dont close your eyes --you will miss the crash
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PostPost by: zeteclotus » Fri Nov 09, 2007 8:08 pm

Avoid Champion spark plug at all costs. I had the same problem.

Sorted by changing to NGK spark plugs. I think the ceramic glaze on the Champion's is not as good as the NGK.

If you measure the resistance of the Spark plug with a Mega. you will see even a relatively clean champion is slightly shorted after a few miles in a Twin cam.

I also lowered my float level by 1mm and that made the engine smoother and more responsive.
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PostPost by: Elvis » Fri Nov 09, 2007 9:48 pm

Thanks to all for taking time to help me out, plenty to try this weekend now, I will keep you all posted.
I am on ngk plugs and I have changed the air filter, and to mark I am alive and kicking

Elvis
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PostPost by: JJDraper » Fri Nov 09, 2007 10:22 pm

My money is on fuel levels/supply or float problem. I had self inflicted float height problems when I misunderstood the method for setting them. Fine at tickover, but lousey on load.

Jeremy
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