Have this G62 that ran great for a while but has got to the point where it just will not idle down lower than 1800 to 1900 rpms..now I know that is not to bad an idle but the throttle plate is completely closed and it should not be running at all. I'm sure it has a vacuum leak but where..I have replaced all the gasket and overhauled the carburetor. I started with the needles both at 2 turns out and in or out doesn't seem to solve the problem. I considered the throttle shaft might leak air by but it is not to loose..

any thought out there...

Sounds like a throttel issue. maybe you have something slipping? Do you use a bell crank set-up. I have a G-62 on my Stinger that you see on the left. I had high idle issues, But was able to get it to a nice low idle using a 440 rod for throttle and using a home made bell crank system. Look and see if there are any binds gfoing on. Check the throttle crank on the engine..Did you take the spring off?

Try to redo the throttl;e linkage all together. I know I did...Where I have my 625 servo was an issue up aginst the Fuse and I had to really secure it in there!...DO NOT USE GOLD ROD!

Use 440 rod and ball joints if all possible.. If not 440 clips...Sloder the ends on. You will have a throttl;e system that will last longer than the plane I
I'll bet!

Remove the carb, with the throttle closed hold it up to a light. You should not see any light, any light you see is an air leak.
DID you remove the throttle spring??? If so you probably have beat up the edges of the buterfly and that where the leak is.

apart from the butterfly valve fit, and only after checking that, check the crank shaft seals and cylinder foot gasket. At idle, air may be drawn in preventing a low idle, and also increasing the effort needed for starting.

All good suggestions ..already have 4-40 linkages and ball joints and have taken throttle loose while running and held the throttle closed to make sure it is closed fully..I replaced the butterfly cause the old one did have some very small dings where it had over time rubbed against the throtle bore..looking through the bore the only light is the small notch at the bottom of butterfly which is factory.

The carb didn't have a spring on the shaft when I bought it but the slack was taken up with a nylon washer so the butterfly would not move back and forth. I have replaced all gaskets including the carb base gasket. The engine starts great and runs good at high RPMs

The crankcase halves gasket does appear to be wet and might be leaking but not sure if this would cause idle problems. I even sprayed WD40 on the throttle shaft and other gasket areas while running to see if there was a vacuum leak and didn't detect any change in RPMs.I'm out of things to do..anyone else have any more suggestions/

Hey Ralph do you have any suggestions?

Lokks like you covered everything...Maybe the bore is worn slightly from the throttle plate rubbing at the edges, wouldn't take much...If it is you could try to solder the small notch closed...

Ralph,
That is an excellent idea headed out to shop to try it..be back later to report results.

Problem is fixed!! There is some wear in the bore where the butterfly in the past has rubbed and scratched the aluminum. I didn't notice it earlier cause it was right up against the shaft and side of bore..I repositioned the butterfly so it fit tighter on that side and it idles much lower..maybe not perfect but much better

thanks Ralph your suggestion got me to look closer in that area and thanks everyone for your response.. I know I can go back and fill the notch in but plan to try it at the field first.

Super Ralph to the rescue.. Faster than a speeding G-62,, leaks er, leaps over tall buildings etc.