Rebuilding 1904 - Need help

[Cheyladd]

Ordered by rebuild kit from IHPA and jumped into the process yesterday. 63 Scout 80 completely original with presumed 50k on it. It was leaking from a number of places so I opted to rebuild. Carb is mostly in great shape. Still has the heat shield under the carb. The bowl is not bent at all and the carb cleaned up well.

My questions:

1- economizer is no good. The spring is messed up and the pin seems pretty worn and was stuck in a down and crooked position when I opened it. The top of the seat area also seems to be a bit bent. IHPA doesn't show the "fixed" one from Robert kenney being available but I will call them to verify. Any suggestions?

2- my throttle linkage is in the outer "cold weather" hole and appears to have been there it's entire life. Just a guess. If I move it to the regular hole, it appears that it is not allowing the accelerator pump to fully disengage. It is close but I might not know until I install it. If it is not fully disengaging I am assuming it is going to constantly be dumping fuel but I could be wrong. Thoughts? It was running fine in the outer hole but I was also getting 10mpg.

3- I am in socal and the main jet is a 62. I read a number of sites that mentioned 59 as the standard. Ok to start with the 62 or is it going to be too big?

I have read the numerous threads, all very helpful. Thanks in advance for any help.

 

[ojh]

They made a few different 1904's, it'd be best if you posted pictures of what you have. There are parts and pieces of those that don't interchange, esp the linkage pieces and how they operate the accelerator pump and the pieces that make up the accelerator pump itself - I recall there being 2 different lengths.
I've done a good number of them and even ganged 3 of them up for a 6cylinder so I can help you but pictures are needed.
Oj

 

[Cheyladd]

I will get some photos taken. I am pretty sure the accelerator pump is correct because the other one is quite a bit longer and mine is only off by maybe 1/16 of an inch.

 

[Cheyladd]

Photos:

 

[ojh]

Sweet truck!
If you need another 'metering block' I have a few spares, as far as I know they are interchaneable. I recall something about an internal check ball being different, it is accesible from the other side - it has been a couple years since I did one of those and my memory is vague.
What about the operating shaft that sets down on top of the 'economizer valve' is that piece ok?
Have you figured out how take the accelerator pump shaft apart? The lenghts have to be exact, you mentioned a 1/16th difference.
The linkage plates and some externals are different from the 1904s I have worked with, probably proprietary to IH's.
There were a couple different linkage pieces to operate the accelerator pump, the early ones were steel and later were plastic. A link rod will actuate it and it'll act as a bellcrank to operate the accelerator pump arm - is yours in good shape?

 

[Robert Kenney]

Nice Scout, welcome to the IHPA forms.

You are probably good with the hard parts that you have. You have the correct plastic accelerator pump cam and linkage.

The metering blocks have a 4 digit number stamped into them that references the calibration that is built into it. You don't want to swap them around.

The economizer valve is an unfortunate issue. I used to rebuild piles of them that michael mayben sent to me and I sent them back. That service ended when mm retired or whatever you want to call it. Now I only do my own. It May be revived some day but for the immediate future it does not exist.

You say it was running well other than the leaks so that's good.
Install the rebuild kit and you should be good.

One detail is the accelerator pump push rod. It attaches to the diaphragm with a tiny steel ball. They disconnect only after sliding free of the bore. Some times they will stay together and pop apart, the ball is then launched into the twilight zone, never to be found again. Be careful and if you want, place the carb in a 1 gallon ziploc bag while you remove the pump rod.

 

[Cheyladd]

Thanks to both of you for the compliments and insight. I think I am going to put it back together and see what it does. I have already pulled everything apart and managed to retain the ball so we are good.