Balancing throttle bodies

[allegro]

I have an SLR. I know they are lumpy at bottom end, especialy when cold, but mine appears to be getting worse. Is it likely that the TBs need balancingquestion.gif If so how is the best way to go about doing it question.gif

Many thanks

 

 

Andy Mac

teeth.gif Out of Control RED SLR teeth.gif

[oilyhands]

There is a balance screw on the linkage which moves the TBs throttle quadrants WRT one another. Measuring the airflow thru each barrel ought to be done with a manometer on the throttle plate side of the engine, but that isnt possible with the TBs.

 

The air can be measured at the trumpet using any airflow gauge, there are several types, some use an airflap and gauge, others a manometer style scale, alternatively you can use 18 inches of small diameter tube sitck one end in your ear and listen in each trumpet for the 'clack-clack' of the inlet pulse, when the volume of this pulse is ths same between the front and rear body then they are in balance.

 

It's not usually possible to belance each individual runner because they are generally joined together in pairs. It is usually convenient to compare the innermost two barrels between each TB since moving the gauge from one to t'other is easier. Adjust the balance screw until the two barrels are drawing the same amount of air, you may find you have to adjust the idle up or down as you do this.

 

There is a certain amount of air which is modulated via the IACV on some TB systems, this of course doesnt necessarily enter the engine via the TB trumpet ands hence will not be measured.

 

Oily