slow idle on SU carb

Technical advice Q&A

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kgb123
Posts: 121
Joined: Mon Oct 08, 2012 7:41 pm
Location: Leighton Buzzard
Wales

#1 slow idle on SU carb

Post by kgb123 » Mon Oct 08, 2012 7:49 pm

Hi,
I am giving the carbs on my car some loving at the moment and noticed that the slow idle screw on carb 3 (nearest the front of the car) does not have a slow idle screw in place. I thought it may have been lost but on inspection the port appears to have a blanking plug fitted within the body of the carb. Is this a normal configuration? This carb also has the connection to the adv/retard on the distributor and I am wondering if this is why there is no adjustment on this particular carb.
Carbs 1 & 2 have the screws as shown in the various diagrams and manuals.
Is this a normal configuration...or do I have a problem?
Thanks
Kevin

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ChrisC
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#2

Post by ChrisC » Tue Oct 09, 2012 11:13 am

The front carb is correct in having the vacume feed to the distributor but is wrong in having a blanked off idle screw.

Its not a problem unless you are going full concours as its not original but it does mean that setting the idle speed on the front carb needs to be achieved using a different method to the other 2
1964 FHC 4.2
Etype restoration blog http://connor.org.uk

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christopher storey
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#3

Post by christopher storey » Tue Oct 09, 2012 6:06 pm

The screws and the neoprene inserts for the seat are easily available from Burlen Fuel Systems. Without this idle screw, you will have virtually no chance of setting up the throttle linkages to work properly because to get any reasonable idle , you are likely to have to have the front carb's butterfly opening well in advance of the other two , and thus the engine will run roughly throughout the range

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