Tale of woe....

[Justmike]

Just needing to vent. Been chasing an off idle stumble problem for a long time. New plugs. Valve lash done. Air filter done. Fuel filter done. Throttle bodies synched. Timing checked. Compression good. Temperature sensor tested. Finally tracked it down to incorrect injectors installed by PO. Installed correct injectors and noticed immediate resolution. Yippee!!!
As a last step performed the lean drop tuning of the air flow meter and had it set just perfect. Because I'm anal, I decided to wind the bypass screw in and count how many turns it was set at so I could record it in my maintenance records. Started to wind it back out......and it started getting stiff. Turned it back in and started to back it out, and it got stiffer. Squirted some lube down the hole and tried again. Tighter. Disassembled the airbox, took the meter out, sprayed in some carb cleaner,M sprayed in some lube, tried turning again.....now it's locked up solid, about a half turn from fully closed. WTF!!!!
How to go from high to low in about fifteen minutes.
Is this thing now a paperweight, or has anybody been through the same issue and managed to salvage it?

[Poconoeagle]

Sounds like the carb  cleaner got the threads the gall.   Try a better lube like kroil  or even PB blaster

[Laitch]

How to go from high to low in about fifteen minutes.

Maybe this is a sign for you to quit being anal. Certainly the view would improve. :giggles

[Justmike]

Maybe this is a sign for you to quit being anal. Certainly the view would improve. :giggles

Ain't that the truth!

[Justmike]

Figuring I had nothing to lose, I decided to drill out the old plug. With a lot of luck, it drilled out very easily, and I managed NOT to bugger up the seat at the bottom of the hole 😅
What surprised me even more was the presence of an o-ring ABOVE the threaded area, so any of the cleaner, penetrating oil or lube I was spraying in there had no way of reaching the threads. I'm presuming this would also have kept any dirt out of there, so what caused the threads to bind up solid is beyond me - just lucky I guess.
31/64" drill and a 9/16-12 tap later, the original buggered threads are gone and I've got a nice clean threaded hole ready for a new plug. Just gotta find a 9/16-12 X 1-1/2" long set screw to start with and I think I've got a good chance of getting this thing to work again.

[Poconoeagle]

McMaster-Carr.  Is a source if all else fails.

[bocutter Ed]

McMaster-Carr.  Is a source if all else fails.

Canadian Tire I  think ...

Gotta wonder tho, why not use a metric tap size. Next owner will be cursing somebody.

[rbm]

Canadian Tire I  think ...

Gotta wonder tho, why not use a metric tap size. Next owner will be cursing somebody.

Agreed.  Keep it metric.  If CT doesn't have it, try Aklands-Grainger, or Bolts-Plus, or Brafasco.

[Justmike]

Canadian Tire I  think ...

Gotta wonder tho, why not use a metric tap size. Next owner will be cursing somebody.

Ummmm...not sure why. What are the chances of having to replace that metering screw again?

[Justmike]

McMaster-Carr.  Is a source if all else fails.

Found just what I wanted at McMaster-Carr. 👍
Placed the order, and was later notified they cancelled it as they to not sell to "private" consumers in Canada.

[Poconoeagle]

What is the part number? If you want I’ll get it and send it to ya or seek a local machine shop or industrial plant and see if they will...

[Justmike]

What is the part number? If you want I’ll get it and send it to ya or seek a local machine shop or industrial plant and see if they will...

Extremely kind offer Poconoeagle. Good to know that's a option.
I had already tried the retailers others in this thread had suggested - I certainly would have thought that at least one of them would have it, but apparently 9/16 set screws are a real oddity. If only I had gone metric like others suggested - Ackland-Grainger had all kinds of M14 set screws 😂
Waiting for a call-back from Bolt&Nut - fingers crossed.
If all else fails, I retired from an industrial plant five years ago - where I used to buy tons of stuff from McMasterCarr! Pretty sure my replacement would be happy to order from them for me.
Thanks again for the offer.

[Poconoeagle]

Your welcome. Anytime.  There is the helicoil or threadsert Avenue as well if you still want Metric..:)

[Justmike]

Your welcome. Anytime.  There is the helicoil or threadsert Avenue as well if you still want Metric..:)

I was looking at the thread insert bits at McMaster-Carr as well - was considering a needle and spring setup, but the sizes and space available were a little questionable, so I figured the KISS approach was the way to go - why look for (more ) trouble 😄

[Justmike]

Success - but I sure wish I had a lathe. As it was turning out to be too difficult to acquire a 9/16" set screw, I ended up just using a bolt (and found out that they're not an easy thing to come by either) and drilled and tapped one end so I could install an Allen screw to use for adjustment and incorporation of an o-ring seal, and grinding the metering end on a disc sander.
Adjusts the mixture just the way it should, although the coarse thread requires less turns to get where you're going.
Bottom line, off idle stumble and rich mixture is gone - runs like a top just like I remembered it.

[Poconoeagle]

Hurrah! That’s the ticket!! Nice 👍