Lotus Elan

trouble with newly fitted dellortos

PostPost by: dgym » Wed Jan 11, 2017 9:57 am

Hiya,
I've recently gotten a hold of matching 40E Dellortos, had the bodies professionally cleaned and rebuilt the carbs myself. The reason for the new carbs was that one carb on my car was a 40 with 3 progression holes, while the other a 40E with 4 progression holes. I didn't like this.
So having fitted the new rebuilt carbs (jets stolen from the previous carbs) I'm having trouble setting them up.

The idle is regularly rising and falling. In a repeating sequence. I've checked for vacuum leaks and all seems ok.

I have a vac gauge ready to test with but the idle not staying regular I can't even tell if a screw in is raising the idle or a screw out is raising the idle.

any ideas besides vacuum leak?

It is a repeating sequence of high idle to low and again and again.

cheers.
-Jim
36/6612
1967 S3 Coupe (left the factory in 66)
original rego PPC 8E
original owner B.M. Wetherill ..are you out there?
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PostPost by: richardcox_lotus » Wed Jan 11, 2017 10:19 am

Try disconnecting / plugging the vacuum pipe(s) going into the headlamps / brake servos, just to ensure no red herrings from faulty non-return valves.

Regards,
Richard
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PostPost by: William2 » Wed Jan 11, 2017 11:51 am

Hi Jim,
I also have twin 40E Dellortos and have a problem whereby the idling is erratic and quite often sticks atb about 1200 to 1400 rpm. Read my thread dated 4th December headed "Dellorto Idling Frustration". It may help. As Rohan has suggested I need to get round to checking the progression holes are covered by the butterflies. Unfortunately My wife has diverted my time to house decorating!!
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PostPost by: dgym » Wed Jan 11, 2017 7:13 pm

Thankyou Richard and William.

I will try plugging the headlight hole today,

in regard to the throttle opening past the progression holes, should the butterflies be fully closed at idle? or should they be adjusted slightly open?
Rohan's suggestion seems the best explanation of what's happening on my car so i'll spend some time on that today also.

thanks again!
36/6612
1967 S3 Coupe (left the factory in 66)
original rego PPC 8E
original owner B.M. Wetherill ..are you out there?
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