Throttle Butterflies

[marcus1970]

Boring stuff, but how can I tell If the throttle butterflies are completely closed?

They look closed, but with a minor change in throttle position, to my untrained eye, they still look closed.

Any help appreciated.

MB

[Julian64]

They never do close, else your engine would stop

With them off you just shine a light in from the back.

On the car a syncro probably a good bet.

Otherwise big flat plate, and cover the throttle body inlet. If the car falters or revs decrease then you still have air going past. The bigger the change the more air.

[marcus1970]

Are they not completely closed when the car is switched off?

MB

[Julian64]

Don't think so.

Easy way to tell is to stop the engine, and pour a bit of neat fuel in the throttle opening, see if it goes through.

I have mine in pieces on the bench at the mo or I'd do it for you.

[trackcar]

they'll never completely close, they're held open by the throttle stop normally, but even if you wind this of completely production tolerances means there will always be a tiny air gap. You should be able to make teh car stall by winding the throttle stop off though, ie you should be able to make the air gap so small that there isn't enough air flow to keep the engine running.

[marcus1970]

trackcar said:

they'll never completely close, they're held open by the throttle stop normally, but even if you wind this of completely production tolerances means there will always be a tiny air gap. You should be able to make teh car stall by winding the throttle stop off though, ie you should be able to make the air gap so small that there isn't enough air flow to keep the engine running.

What should the pots read at this engine failure point? (ie throttle stop wound in and no/very little air going in - if any)

MB

[trackcar]

marcus1970 said:

trackcar said:

they'll never completely close, they're held open by the throttle stop normally, but even if you wind this of completely production tolerances means there will always be a tiny air gap. You should be able to make teh car stall by winding the throttle stop off though, ie you should be able to make the air gap so small that there isn't enough air flow to keep the engine running.

What should the pots read at this engine failure point? (ie throttle stop wound in and no/very little air going in - if any)

MB

that depends on what they were before you started winding the stop out .. but say they are 17% at idle they'd be somewhere around 14% fully closed, but depends how far they move, which depends how central they are on the throttle spindles so pretty much a useless number to try and aim for.