Throttle linkage adjustments?

[MHunter]

Is there a standard procedure I'm not aware of to adjust the throttle cable so the carb is fully open just when the pedal touches the pedal stop? I loosen the cable, then ask a friend to hold the pedal to the pedal stop, then I manually open the carb, adjust the cable so it is tight and screw it in. My assistant then releases the pedal and when he floors it again to test it, the carb doesn't open fully, there's still about 1 cm of movement available. It gets worse if I install throttle return springs, then the carb opens up maybe 50%. The cable isn't sliding at the linkage.

Thanks

[ROWDYRENAULT]

You have to be very careful how you align the cable going into the pedal it needs to be as straight a shot as possible. I would start by pulling the cable and applying the appropraite lubricant just to make sure and keep the cable as straight as possible at both ends. Lee

[Steve_D]

The whole system has an element of stretch to it so starting with the pedal down is not taking up any of the stretch.
From where you are now just take up a little more travel at the carb and have your assistant take the pedal to the stop. If the carb is not fully open have the pedal released and take up a little more slack and try again.
There will be very little difference in performance from the last few degrees of butterfly opening so best to set it up so you can just open the carb a fraction more when the pedal is down. Do all of these adjustments with the return springs in place.

So now you have set WOT you must now go back and check closed throttle. You need to ensure that the cable has some free play (lash) when closed. If you don't then when the engine bay gets hot the cable outer expands and starts to open the throttle preventing the engine from going back to idle.

If you have issues where you cannot achieve WOT and idle with one setting then you will have to start fine tuning both the idle and WOT stop positions at the pedal. You may also have even bigger issues where the ratio of pedal movement and carb movement is mismatched in which case you may have to drill new fixing points at the carb lever.

Steve

[MHunter]

Ah, thanks. that makes sense. Adjusting the cable so it is as straight as possible going to the pedal will be interesting, with the car completed. Can someone explain where that element of stretch comes from, with an aircraft-quality steel cable? Just how it moves inside the jacket, and maybe the jacket itself flexing a bit between the pedal and the carb?