Weber air leak?

PostPost by: JHE007 » Tue Jan 31, 2012 1:36 pm

I have a problem(s) with the Webers on my +2, there are two symptoms which may have a common cause. The symptoms are that the engine will not idle below 1300 rpm and that one of the idle mixture screws has no impact on idle speed (the other 3 are fine). The one idle mixture screw was feeding the first cylinder. Unsuccessful attempts to isolate/fix the problems so far are:
Serviced both Webers, replacing all gaskets
New o?rings and thackerys for the connection to the inlet manifold
Blanking off the vacuum take-offs for headlamps and brake servo.
Swapping over the position of the Webers. Same idle mixture screw still having no effect on idle.
From reading the other posts I think this points to an air leak somewhere in the carb. The fact that swapping the Webers over had no impact would suggest to me the leak is not around the o?rings. When servicing the suspect carb the butterfly valve seemed to seal as well as any of the others. Looking down the inspection hole showed it in same position as the other valve at idle. So my question is how to trace the leak (if it is one), and could it be anything else?
Any suggestions would be much appreciated.
Regards
John
User avatar
JHE007
New-tral
 
Posts: 6
Joined: 14 Jul 2010

PostPost by: quaybook » Tue Jan 31, 2012 6:10 pm

Hi John

Do the carbs balance ok? Mine wouldn't and it turned out to be a twisted butterfly shaft. I'd inspected it visually through the progression drilling access and also by shining a light through the choke and I couldn't see a problem, but that is what it was. My only other thought is the startup enrichment device - if the plunger on that choke is not sealing properly.

Vernon
Elan S2 26/5614
Alfa Romeo Alfetta Berlina 1974
Westfield 7SE
quaybook
Second Gear
Second Gear
 
Posts: 128
Joined: 24 Aug 2009

PostPost by: prezoom » Tue Jan 31, 2012 7:26 pm

Difficult, but check the leather seals on the throttle shafts. Mine were completely dead, dried out and had shrunk away from the shafts. Installed new ones with new caps, but before, saturated the seals with with leather conditioner.

Rob Walker
26-4889
Rob Walker
26-4889
50-0315N
1964 Sabra GT
1964 Elva Mk4T Coupe (awaiting restoration)
1965 Ford Falcon Ranchero, 302,AOD,9",rack and pinion,disc,etc,etc,etc
1954 Nash Healey LeMans Coupe

Owning a Lotus will get you off the couch
prezoom
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1176
Joined: 16 Mar 2009

PostPost by: DeanG » Wed Feb 01, 2012 11:19 pm

Spraying carb cleaner around the can help show leaks. If the rpm changes after a shot of carb cleaner it is a good indication that you have found air leak. The 2 previous posts are in line with my experience. Good luck.
DeanG
Second Gear
Second Gear
 
Posts: 90
Joined: 16 Apr 2011

Total Online:

Users browsing this forum: Fred Talmadge and 30 guests