rough idle on 74 eldorado

[Viator Trudeau]

Rough idle on my 74 eldo seems to be a vacumn leak. I have isolated all the usages.
Starting fluid into the secondary bore rt.side causes engine speed up.
I figured air bleeding   past secondaries would lean the mixture.
I removed the throttle plate on bottom of carb.
I saw light around between the plates and the bore.
When the plates are closed how much space should there be?  Air tight???
Does any one have any information on this?
Thanks,  V. Trudeau

[The Tassie Devil(le)]

These plates should be closed shut.

Allowing air past them will have an affect on idling.

But only increasing the idle by squirting on the one side would indicate a problem that needs correcting.

Bruce.

[Gene Beaird]

Yep, secondary butterflies should fit tightly against the base plate bores.  There are a number of possible issues that can cause them to not close completely, most of them usually mean someone's been messing with the butterfly plates themselves, and not in a good way.  Can you post pictures of what you have? 

[Viator Trudeau]

Gene:  The throttle plates are closed tight, but holding a light on one side and viewing the other side a bit of light can be seen in about 15-20% of the circumference of the plates. should they be air tight or air tight?
I think any little bit of air by passing can be balanced out W/ the idle needles.
V.Trudeau

[R Schroeder]

What Gene said.

There should be no light seen through the bores.

[TJ Hopland]

Worn throttle shaft bores can cause that.  There are enough springs and linkage things that if the bore is worn it wont hold the shaft centered so one end of the blade hits the bore sooner.   In theory the blade is supposed to wear before the bore so what ever side was hitting has just worn down leaving a gap at the other end. 

You can buy repair kits for them but they are fairly expensive so its usually cheaper to have a shop do it than buy the kit if you only have one or two carbs to do.   The kits have special stepped drill bits to make it fairly easy and can be done with a hand held drill.