1980 15 hp idle....not

[Joe Reeves]

9.9 Part needed.......

My email is gr49(at)comcast.net

Reply sent to email address.

[hairtrigger]

I located the trouble

First, after thinking about this, the extra fuel could only be coming from the low speed circuit. No air velocity to draw fuel from the main jet, the new float needle was closing off the fuel so it was not flooding.

I wondered if the low speed needle was truly seating. It looked good not bent clean and shiny.

I put black marker on the needle and run it in till it stopped and the needle was only clean on one side and only about 1/4 was clean. I thought it was coming up against one of the ledges on the shaft. So I put black marker on the two ledges one at the brass end and one just behind the needle.

Run it in again Nothing touched them. ???

Now I am in break it or fix it mode. I run the shaft back in until it seated (stopped) I am going to work this back a forth until I get the needle to seat.

Each time it would feel it seat (stop) I torqued a little harder about the 3rd or 4th time the shaft suddenly spun another turn closed !!! again I torqued hard when it stopped and I got another full turn !!! Then it really did stop. When I started to remove the shaft I could feel both of the hard places. Now the needle was rubbed clean of the marker.

I am not sure what is binding in there but it caused me to think it was closed when it was 2 turns open at the start ! Looking at the shaft just behind the needle it appears to be rubbing the side of the hole. No it is not bent I put in my lathe and it was not bent wobble maybe 2-3 thousands. I believe if I take a couple of thousands off of this part of the shaft that would cure the problem.

I hope this make sense. I know my blood pressure is lower.

It idles now and I can lean it down till it dies.


GR

[hairtrigger]

When I placed it in the lathe to shave it down I put a dial on it and at the shoulder behind the needle it was 6 thousands out. I didn't think it looked that bad the first time.

So the shoulder behind the needle must have been hitting the casting and preventing the thing from closing. To simple to see, I guess.

At $44 bucks for a new one I hope I can straiten it out!

Thing is how did it get bent in the first place?

I'll bet this is why the boat and motor was up for sale. A motor that loaded up and quit when idling would not be any fun to fish out of.

GR

[hairtrigger]

Nope I have it strait inside 1 thousand and I still have the tight spots.

I know I am pushing this but I want to run a tap down there if i can find the right thread size I'll grind off the tap so it will chase the entire thing. Something is causing the shaft to bind up before it bottoms out. Hope it is a standard pitch. Don't you want to know what the %^&* is going on? I do I really do. Is it something ground into the threads? or what? Down to about 2 inches of low speed adjustment shaft. Yes I chase every thing this way. This is why I don't get any thing done. (Ask my wife) And I just wanted to go fishing ............

GR

[hairtrigger]

Well I am done. I ran a tap in (1/4-28) and I run a die over the shaft and the tight spots are still there.


Any thoughts?

I am going to put it back on the engine and just live with it. It's a lot better with the adjustment knob on so it'll work for me. Inquiring minds would have liked to know why.


Thanks
GR

[Joe Reeves]

Yes, $44 bucks for a brass or SS needle valve is a pretty steep price I'd say.

I assume by what you've had to say that the tapered needle itself is bent somewhat but the rest of it is okay including the threaded portion? If so, that's quite strange UNLESS someone has at one time dropped it.

If you have it gripped in a drill, turning slowing....what you you see?

[hairtrigger]

Hi Joe

Joe I put it in my small lathe and straitened it. But I was gripping the entire brass part of the shaft in the chuck. The needle part was out by 6 thousand. I have it strait now with in 1 thousand. I thought when I did that it would work OK, but the final two hard turns are still there.

In saying that, what I needed to look at is the entire shaft end to end not just the needle. I am not sure how to do that. One would have to support the thick part of the needle and somewhere just as the threads start on the other end then get a dial on the middle. Keep everything steady to get a reading.

Yes $44 is to much.

GR

[Joe Reeves]

I wish you luck my friend. That is really one strange problem. If someday, you find out what is causing that tight spot, I'd like to know about it. (Joe)

[hairtrigger]

I now know what is going on down in that hole. After putting the needle back in the lathe and finding the tip bent 6 thousand again. So once again I straitened it. After screwing it past the two hard spots, I removed it, and it was bent a second time about 7 thousand.

The only way this could be happening is if the small hole that the needle tip was to seat in was off center.


The hard turning happens when the needle tip is being forced to the side (this case it was forced up) as it enters the small hole it is to seat in. During the last two turns.

How to check this? Or better yet how to fix it? Is it repairable?


I placed a #5? drill in the hole and it is drilled up from entry to exit about 5 or 6 degrees..UP! how did that happen?

This thing must have been made on a late Friday afternoon.


I am just happy I understand why this was going on.

GR

[Joe Reeves]

That is strange indeed but it does explain the mystery.

I wonder if, in the past, someone broke off the tip of a slow speed needle valve in that small hole (it does happen)... and then attempted to drill it out?

[hairtrigger]

Fixed !!!!!!!

I repaired the carb like this.......

This is a #57 in the low speed idle hole a tight fit but you can see it was drilled
off center about 10 deg.

[hairtrigger]

I made up a drill holder for a 1/8" drill that held the bit dead center.

Then drilled a 1/8 hole where the #57 hole was.

The set screw was 2-56 tuff to get it started !!

[hairtrigger]

Then I turned a small billet out of 3/16" aluminum rod.

to a press fit in the hole I just drilled.

Then I peened it in. I used my drill holder with a 1/8" drill shank in it

Bucking against a large drill bit that just fit in the chamber hole.

[hairtrigger]

Then I made a drill holder for a #57 drill with a short shank so it would not
wander around before it started then after it got a start I put a longer drill
bit in it and went all the way through the peened in billet

[hairtrigger]

A bit much I'll admit but I am retired and have the time and the equipment and

I "most" always get my man........


Who the hell drilled the original hole off center??

The engine runs at idle like it should now, that's all I was after

GR