Lotus Elan

Running on one weber :(

PostPost by: "nebogipfel2004" » Sat Jun 18, 2005 8:37 pm

Ok Guys,

Just fired up my S4 after a long rebuild and it appears to be running
on one carb!

Any ideas why this might happen? (Standard twink on twin 40 webers)

Static timed to 10 btdc, all the ignition stuff is new but the front
carb doesn't seem to be doing anything (there is fuel up to it)

Keep it simple please, I'm a painter not a mechanic

Thanks

John
"nebogipfel2004"
 

PostPost by: "Tim Engel" » Sat Jun 18, 2005 10:05 pm

From: "nebogipfel2004" <***@***.***>
Just fired up my S4 after a long rebuild and
it appears to be running on one carb!


John,

There should be a carb balance screw in the linkage coupler between the two
carbs, and it's probably way out of adjustment. Does the non-running carb
pick up if you advance the throttle? If so, then the balance screw is
probably the culprit at idle.

The Idle speed screw sets the throttle position on the rear carb. Then the
balance screw sets the front carb's throttle position relative to the rear.

For a starting point...
Remove the progression hole covers. Look in through the rear carb's
progression holes while working the throttle and you will see the edge of
the butterflies passing the holes. At closed throttle, adjust the idle
speed screw until the butterfly is visible at the edge of one of the holes.

Then go to the front carb and adjust the balance screw until the front
butterfly is in a similar position as close as you can eyeball it. Replace
all the progression hole covers.

Start the engine and re-adjust the idle speed screw.

This only gives an approximate balance... a starting point. If balance
was the issue, then the car should at least fire up and run well enough to
allow for a more accurate carb balancing.


If the engine is still running on one carb, check the fuel inlet valve to
be sure it isn't jammed shut. Check the float setting to make sure it's
not set too low.

Good luck,
Tim Engel
Lotus Owners Oftha North
"Tim Engel"
 

PostPost by: mikecauser » Sat Jun 18, 2005 10:24 pm

On Sat, 18 Jun 2005 20:37:36 -0000 "nebogipfel2004" <***@***.***> wrote:

Just fired up my S4 after a long rebuild and it appears to be running
on one carb!

Any ideas why this might happen? (Standard twink on twin 40 webers)

First thought is to check the order of the plug wires in the the
distributor cap. Second is float height or fuel in the float. Being
really paranoid, if only the front carb works are you sure the camshafts
are all in one piece?


I must admit that I have attempted to fire up an engine timed so the
plugs got their sparks at the top of the exhaust stroke. Not a Twink, a
BMC A-series, my first ever engine rebuild -- from which I learned a
significant number of lessons....


Mike
--
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mikecauser
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Posts: 107
Joined: 15 Jun 2005

PostPost by: "nebogipfel2004" » Tue Jun 21, 2005 9:10 pm

Thanks for the input

It was the throttle pump jets blocked


John
"nebogipfel2004"
 

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