Lotus Elan and Lotus Elan Plus 2 Forums

I have had an Elan Plus 2 for the last copuple of months and as time has gone on I keep hearing a kind of Zuuup (spitting noise) fron the engine. As a novice to these engines and the Webber carbs has anyone any idea why this shouid be so.

In addition the engine do not appear to be smooth at low revs when I pull away, however it ticks over nicely. I expect they might need balancing. Anyone know of any where in the Southampton/Portsmouth area?

Finnally I get a nice tinny rattle from the exhaust when I de-accelarate and if I lie under the car and tap the silence I exhaust pipe along its length I an achive the same ring.

Andrew

dont know about the rattle, but if you're looking for someone who knows all about Lotus, Miles Wilkins is at fibreglass services in walberton is just down the road from you and he doesn't cost the earth

regards Mark

A couple of things which I have found to make the carbs spit back are over-advanced ignition timing and the crap that passes for petrol in this country these days. Shell Optimax works for me with a dose of Castrol Valvemaster plus and now I very seldom suffer from spit back.

It would be worth getting the car set up on a rolling road if there is one near you.

Cheers,

Pete

I'm not too sure on this but it sounds like it could be the carbs. Mine will kinda do a soft "prwap prwap" spitting sound and run lousy at low rpms when they get outta wack. You might want to do a compression check too...
The exhaust noise is probably either a loose baffle in the silencer/muffler or a loose clamp/hanger somewhere vibrating. Also make sure the system isn't touching the underside of the car anywhere, maybe de-acceleration creates engine driveline load movement which is then telegraphed down the exhaust tube.

If it really is 'spitting' then the mixture is lean or the ignition is retarded or most likely both. Easy to diagnose. Tougher to correct. Do a google search to confirm what I've stated.

If it's just a lean condition you can diagnose it by slightly pulling on the cold start choke and fattening the mixture that way and it should stop the spitting.
Regards
Keith

I forgot to mention that I found that on my (Dellorto) engine the chokes had been disconnected, they are not needed, but one of the choke levers had not been seated properly so the choke was "on" slightly on one of the carbs all the time.

Seems like either side of "normal" can make it spit, using a Colortune might be an idea but rolling road will provide the definitive answer.

Check for air leaks to rule out lean mixture.

Pete

Seems like either side of "normal" can make it spit,

Nope. Only according to you. I challenge you to find a SINGLE credible web reference which backs up what you've stated.
Keith

I would not bother with a colourtune I have never found them to be accurate enough. You can get a CO meter now for ?60 or even less from ebay. Well worth the money and it will allow you to get the mixture spot on. The CO wants to be between 2 and 5 with 2 being lean and 5 being rich. I have my S4 set at 4.3 which works for that engine.

Burton sell a very good device for balancing carbs very accurately. Costs about ?50 and well worth it. Takes abot 5 minutes to use. I've used colourtune for years and it seems to work for me. The only problem is that of working out the transition point between just right and becoming rich. If you try to set to blue it seems to be too weak and this causes slight hesitation coming off tickover. I tend to set to just slight yellow which works fine. Hope this helps

the soft spitting sound means [ believe it or not] they are in good balance ed law

the soft spitting sound means [ believe it or not] they are in good balance ed law