Lotus Elan and Lotus Elan Plus 2 Forums

Hi all,

Just had this info fed back to me about the Sprint - could anyone translate this? Although I have a little understanding of mechanical things, carbs baffle me!

"We've tried balancing your carbs but can't get number 1 anywhere near the other 3; we've cleaned and swapped jets, cylinder compression is good, fuel pressure set, and leads changed. However we can not get the car running right"

Could anyone break this down for me in real simple terms! I would be very grateful! The next step suggested is a carb rebuild.

Thanks in advance, Paul

As each carb is a pair and they cannot get 1 and 2 to balance it probably means that the spindle which controls the butterflies in both 1 and 2 is twisted.. which means that while 2 , 3 and 4 are fully closed, 1 is still a little bit open, and so running slightly fast.

You can get new spindles

It could be wear or damage on the flaps themselves, in any case you need to get them off the car and take a look through each carb at the flaps with a light on the other side, it should be dark... if you see a crescent moon of light in number 1 then you need to investigate more.

Well, for starters, they are obviously talking about the circuit / operation of the front most barrel, ie no.1 as compared to nos. 2, 3 & 4, in that they cannot get the mixture or air flow the same on that barrel as the other 3.

Thats how I read it, probably due to a drilling being blocked, and that is why they have suggested the next step being a complete carb strip down and rebuild.

However, there are other things to take into account. Carburettors are not infinitely rebuildable. They wear out and very often a rebuild will not put a set of Dellortos or Webers back to as new, working condition. They might look very bling after a rebuild, but I am far more interested in their correct operation than how they look.

Your carbs, if original to the car, are circa 50 years old. Not a problem if the car has only 50k miles on the clock, but if it has covered nearer 150k miles, then the above could apply. I recently fitted brand new Webers to one of my cars and the difference in running between the old, rebuilt carbs, and the new set, was chalk and cheese. I will always in future, give much thought to whether I rebuild carbs, or replace.

Good luck with them.

Leslie

thats another or THE REAL reason for disconnecting the vacuum (well intended) b.s. as i did: and btw: at our very accurate "MOT" here they loved my solution -------- and didnt consider the/my WHY = cylinder 1!!! sandy

As per Sandy The first area i would look at is a vacuum leak through the head light system on No1.

The second thing would be to check the o- rings and bolt tighness in the head to carb join to ensure no leak

The third thing would be to check the butterfly in 1 and 2 to ensure they are both correctly aligned versus the progression holes.

After that a range of potential carb issues and electrical issues to check before I did a full carb rebuild

cheers
Rohan

Thanks for the all the answers - definite food for thought and a line of investigation before a full rebuild of the carbs.

I'm sure the team working on the car are all over these other possibilities but its good to know and i'll bring them up with them just in case.

Thanks again for the input!