I use one of these
as the throttle body on my RV8. More pics of it here https://picasaweb.google.com/dave.g.smith/4BarrelThrottleBody#, here https://picasaweb.google.com/dave.g.smith/FuelInjectors# and here https://picasaweb.google.com/dave.g.smith/ManifoldSwap#

My problem is that it is reluctant to completely close. The car will be idling circa 900rpm, I'll poke the accelerator, and it will drop back to 2000rpm. I can push it closed fully by pushing on the lever arm. It isn't the cable binding as I've set it up with a bit of slack in it. The required arm travel to correctly close it is <1mm. It feels smooth to operate by hand. I tried lubricating the butterfly pivots (WD40, 3 in 1 etc), but that seems to get washed away by the petrol as at idle the injectors fire onto the closed face of the butterflies.

Any ideas? It makes it quite nasty to drive at the moment.

Regards,
Dave

Stronger throttle return spring required.

Second the throttle spring, looks like a modified Holley carb, most cars over here have two throttle return springs (Muscle cars).

It does already have two springs, one on each side

h
Have you tried recentering the butteflys on the spindles.

+1 for adjusting the flaps so to speak, also check the linkage isnt binding, try taking it off and seeing if it returns home without it.
you may need to bend the linkage slightly to allow both throttles to close fully
Ray

[Edited on 12/2/11 by RAYLEE29]

Thanks all. The springs are tensioned by twisting them rather than stretching, so I've preloaded one of them with an extra twist. See how it goes tomorrow. I've tried getting the flaps off before, but the are held on with slotted screws and I was beginning to strip the head without them shifting. I think there is some serious threadlock in there.

Regards,
Dave

just seen pic of the install check the throttle pot isnt holding it off
Ray

Try squirting the mechanism and butterflies with a little WD40, then exercising them.

quote:

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Originally posted by MakeEverything
Try squirting the mechanism and butterflies with a little WD40, then exercising them.

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I know you say the cable is free but do you have a return spring on the pedal or are the carb springs doing all the work ?

quote:

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Originally posted by scudderfish

quote:

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Originally posted by MakeEverything
Try squirting the mechanism and butterflies with a little WD40, then exercising them.

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I tried lubrication and manipulation but it provided no lasting satisfaction.

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u can actually find springs the same length,but harder,or if you cant find harder ones,double them,