Lotus Elan

was Intermitent smokey exhaust, now Dellorto mixture

PostPost by: Tim Dafforn » Tue May 17, 2005 11:09 am

Hi,
Thanks for all the suggestions,
I am currently running 20 50 castrol.
decided to Spend some of the weekend driving the +2 and monitoring the
smoke. Observations are:
Doesn't seem to be smoking any more!
Only change was to lean out the mixture a little as she seemed to be
running a little rich.
Mixture screws at 1 1/2 turns out and she runs fine which makes me think
the idle jets are a little fat?
Changed to the next richer jets from stock when I got the car as it
seemed to be always running lean (lots of poping from the carbs).
Rebuilt the carbs this winter, and now perhaps we're running too rich.
Also have noticed that the engine seems to return to idle from revs a
little slower eg. 1300 -700 rpm in 4-5secs, springs are all tight,
anyone any ideas?
Will put the leaner jets in anyway.

Still get a reasonable amount of smoke from the crank breather, but have
plumbed it back to the air box.
Cheers
Tim



Tony Vaccaro wrote:

Another thing you can try is 20 50 Castrol GTX...may minimize it a bit.



If you are running 10w/30..(don't know that you are) it is awfully thin..



I vote for guides..



Easy fix..pull the head.do a guide and valve job.



Tony V



_____

From: ***@***.***lto:***@***.*** Behalf
Of e s
Sent: Friday, May 13, 2005 9:41 AM
To: ***@***.***
Subject: Re: [LotusElan.net] Intermitent smokey exhaust



valve guides should be evident on trailing throttle and on startup

weber or stromberg?

weber heads don't have as good an oil drain, which makes me think that
situational pooling[like when you are facing up hill] might occur

If you have 30 psi at idle, either it is never hot or your idle is
high.....if your idle is high you might not notice a intermittently rich
carb, bad needle valve etc



----- Original Message -----
From: "Peter Walker" <***@***.***>
To: ***@***.***
Subject: Re: [LotusElan.net] Intermitent smokey exhaust
Date: Fri, 13 May 2005 22:25:12 +1000



>Tim
>
>Sounds like valve guides to me. These engines aren't designed to have
>
>
valve


>stem seals so the clearance is critical. They shouldn't wear out in
>10000miles but any wear in the guide can potentially let oil go down the
>stem and into the exhaust port which will burn and cause smoke.
>
>You won't pick worn guides from a compression test either as guide leakage
>happens into the port not the combustion chamber. The oil pressure is a
>measure of the health of your pump/bearings and has no relation to the
>combustion part of the engine.
>
>Mine made that little puff of smoke for 8 years till I rebuilt the engine
>and it has been fine for 14000 miles.
>
>Peter
>66S2
>
>----- Original Message -----
>
>
>>smoke on start up. Just at the odd time when I stop in traffic I can see
>>it in my rear view mirror. The engine runs with good oil pressure
>>(>30Psi at idle) and the compressions are within 5lbs across the 4
>>cylinders (average of 180lbs). The compression is unchanged when I add
>>oil to the cylinders. The head was rebuilt by the previous owner <10000
>>miles ago and I have a reciept which includes new guides and seats. The
>>only other thing I have noticed is that when I see smoking at the rear I
>>also get a puff out of the engine breather (Observed when running
>>without it attached). I think the smoke is oil smoke although it is not
>>intense enough to really tell, although the guy who MOT'd it thought it
>>was running a little rich.
>>At the moment I am not too concerned as it isn't effecting the
>>performance, and next winter may be engine rebuild winter anyway!
>>Anyone have any thoughts?
>>
>>





--
Dr Tim Dafforn
MRC Fellow
Biosciences
University of Birmingham
Edgbaston
Birmingham
B15 2TT
(0121) 414 5881


--
Dr Tim Dafforn
MRC Fellow
Biosciences
University of Birmingham
Edgbaston
Birmingham
B15 2TT
(0121) 414 5881
Tim Dafforn
 

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