[ROVERNET - UK] Balancing carbs

Steven Dibdin sdibdin at hotmail.com
Mon Oct 1 16:08:54 BST 2007

Hi Roger, 

It takes a couple of goes to get handy at balancing but once there you'll never forget it. I've used both the Gunson Carbalancer and the Uni-Syn meter for balancing SUs in the past, they are both fine for the job. 

[1] Check your ignition timing and plug gaps. If these are off you will not be able to get a decent set up on the carb's.

[2] Adjust the mixture, as per the book. Try and get things in the right ball park, you can fine adjust after balancing. Otherwise you could end up with just the front or the back carb' only supplying petrol. 

[3] You will need to make/get hold of a couple of short semi rigid tubes to fit into the the carb' inlets, otherwise the air filter housing studs get in the way of the meter. 

[4] Loosen the nut on the coupling for the butterfly spindles (It's near the back of the rear carb'), don't go crazy with these they fall out and then you spend the day on th egarage floor trying to find them. 

[5] Offer up the meter to front carb' note air flow on gauge and then chck the rear. If it's higher at the back, adjust the front idle control until they both read the same. Don't worry too much about idle speed at this point. 

[6] Once you have air flow balanced between the two carbs', you can retighten the spindle coupling mentioned in step 4 (Don't over torque these chaps, I have had them shear on me in the past) Just tighen enough that the spindles are clamped firmly.

[7] Check your idle speed, for a TC it should be 800 rpm -/= 100 rpm, if memory serves. If it's too high (propbably is!) adjust both idle controls by same amount (1/4 turn front-1/4 turn rear) until the speed is correct.

[8] Check mixture settings. They should be close but you'll be able to tell engine speed changes a lot easier now. 

[9] Tighten all lock nuts on idle and mixture controls. I made a 1/4" spanner with a 90 degree bend by the cresent so that I could get it into the stupidly tight spaces available.

[10] Replace airfilter housing.

[11] Have a cuppa.

Hope that helps some what. 


Steven D

> Date: Mon, 1 Oct 2007 19:25:22 +1000
> From: roger.matheson at bigpond.com
> To: rovernet at lyris.ccdata.com
> Subject: [ROVERNET - UK] Balancing carbs
> Hi guys,
> I want to balance my 2000 TC carbs as I think idle and mixture are out. Have contemplated various methods including pipe and ear, Gunson, mercury tubes, colour tune etc. Please advise dear colleagues. Should I make connections into the manifolds for vacume guages, or should I mow the lawn instead
> Cheers Roger
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