1904 Rebuild

[brained]

Ok, my 1904 is peeing fuel out from underneath somewhere and I bet it's impacting how it drives as well as affecting the mileage.

Mm has sent me the proper wells rebuild kit for it and I'll start breaking it down over the next couple days here.

I've read this And this Several times (and printed a hard copy).

I also have two other 1904's I've acquired on parts rigs, one in known running condition.

I'll power time the dizzy tonite as part of the prep for the carb install.

Couple getting started questions.

Cleaning:
I have clean solvent I'll use for the bulk of it?
The lower throttle body assembly seems to be made of a ferrous material. What to clean it with to get the crud off? I'm thinking after a solvent soak and scrub with a stiff plastic brush of using the dremel with a polishing wheel and some fine jewelry type polish?

E10:
looking thru the rebuild kit I see at least two rubber diaphragms and the inlet needle is not solid metal (has a rubber or synthetic tip). Are these items known to have issues with e10?

 

[Michael Mayben]

The throttle body on that carb is cast iron. The rest of the metallic components are die cast zinc.

I soak all parts simultaneously in tyme cold parts cleaner which is safe to use on rubber components (including synthetics). Ya need to leave the stuff in tyme no longer than 24 hours and then do the hot water rinse immediately, then blow dry. Longer than 24 hours will lead to deterioration of the surface finishes.

Then I mechanically clean the surfaces/passages with an assortment of about ten different pattern steel brushes, either mounted in a drill press or in a pneumatic or electric die grinder, or dremel flexible shaft hand piece.

I also use many other cleaning techniques depending upon what it is I'm trying to sterilize! But never do I use an abrasive blasting process whatsoever!

Currently...e10 will scruu up anything over time. But I have 1904 carbs running throughout the us that have been in service (most sit for extended periods of time on project vehicles) for 2 plus years exposed to e10 or worse! I seriously doubt we'll ever see "e10-resistant" parts for these old carbs, there is simply no market for that stuff (or carburetors for that matter!). But the good point is...all the 1904 floats are brass!

The 1904 on my s80/196 test mule has now been in service (and sits for days/weeks at a time) for 16 months, and so far no e-10 related issues. The sight glass fuel bowl came off that carb last Sunday nite, all that was wrong was the gasket was bunged as always.

I've done n=5 1904 carb builds since the Binder Bee, only one of those was correctly assembled with correct parts at some time in the past, all the others had issues with wrong parts installed. While the 1904 carbs appear the same, there are many subtle design changes over the years, most especially the type of accel pump cam used vs. The type of "plunger" used on the pump element shaft and the length of the pump element shaft itself.

When ya have the carb totally disassembled into pieces, lay 'em out onna clean background and shoot some good pics so I can see what parts ya got and advise if anything is not right, that will save some grief and frustration down the line!

 

[brained]

Got one broke down tonite. This'll be called #3 since it's the 3rd one I've acquired. It's off a 66 that was used for mud bog racing until they tore the underneath up too much.

Tyme cleaner is unobtainioum locally, I'll have to get some shipped in.

You can view the full gallery of pics here - repeatedly clicking on each image in the gallery will progressively enlarge it beyond the mid size images posted below.

 

[brained]

I had wanted to get more pics up of the other two carbs but it was deteriorating so fast I couldn't even power time it and was going to be walking to work.

So I did the rebuild last night and here are the results along with some questions.

First timed it to 0tdc by hand.

Of the three economizer valves zero are in proper working order. One has a broken/missing spring and hangs open (#3), one (mine) sticks open (#2), and one doesn't have a poppet (#1). It has a small steel ball instead. It'll actuate fine with the tip of a screwdriver but there's no way for the power valve to do so since it's completely recessed inside. So #1 is permanently closed. It looks like all three have been slightly abused with a screw driver. I guess it does kind of look like a jet that should come out.

I installed #1 the thinking it would be the best for getting around town/back and forth to work.

The source of the fuel leakage from below turned out to be the accelerator pump gasket. It was passing fuel to the dry side of the gasket and each stroke shot equal parts fuel into the carb and out the vent hole on the bottom.

After putting the carb back on power timing went quite well. It now idles smooth, needs minimal choke to start, no stumbling when switching from cruise to acceleration, no backfiring when compression braking. Accelerator pump is on the long stroke for now, I'll probably move it back after getting the economizer valve working properly.

I have yet to confirm that the throttle plate is being opened all the way, too dark last night for climbing on the engine.

Inlet needles - two tipped with a solid body, one all steel (no tip) with a spring loaded contact on the bottom. One tipped solid body had a small spring in the inlet body that the float pressed against.

The inlet needle in the kit is tipped with a hollow body. After placing it in and attempting to set the float I noticed that all the action was coming from the retaining spring, the float wasn't even touching the needle. I kept the all steel needle w/spring contact and matching inlet body instead.

All three have a #62 main jet. Is this roughly appropriate for 3,000 to 6,000 feet? I'll get some new plugs here shortly so we can see how the burn looks.

The large steel ball in the kit goes where? Looks like part of the accelerator pump.

There is a port hole in the throttle body to intake gasket that leads nowhere?

Mm if you could see your way to sending out a replacement economizer valve I'll send a core and payment out Friday?

 

[Michael Mayben]

Sorry I've not caught up with posts today, lot's of action around here!

What you are seeing with that triple set of 1904 carbs is typical! Butchered and po'd at some point in the past!

The main well with the "check ball" economizer is actually wrong for a 1904. That one is used in the "early" version of a 1920...which was the "next generation" version of a 1904 as smog carbs began to take hold in the marketplace. And it's actuated by small, nylon pivoting plunger, it pivots from a cotter pin as it's fulcrum. The economizer actuator is the same though, even though the entire carb body is different. Some parts do interchange between those carbs. And...there were also Holley 1906 and 1908 versions in between those bookends! And then the 1940 1v carb was far more sophisticated/advanced than the 1904 and 1920, those were true emissions carbs with all the bells and whistles and complications!!

Look at post #23 in this thread and you will see the "single stage" main well assembly that should look like the one you have which is incorrect for the 1904:

http://www.forums.IHPartsAmerica.com/carb-tech/510-Holley-19xx-series-carb-stuff.html

The all-brass float needle vs. The synthetic tip version is not a dealbreaker. And some have a "spring-loaded" contact point or the float, some don't. What is important is keeping the parts that come in the kit together and not interchanging one needle with a different seat assembly. Remember, in past history several companies made service kits for these and many other carbs...and in many cases they actually made (or had manufactured for them) proprietary components like the needle/seat assemblies so they are not all alike.

Look very carefully in the packaging for that kit I sent you, you should see a tiny brass plunger along with a equally tiny spring, that is the rest of the components for the float needle that was in the kit!

The steel balls in the kit you will not use unless ya remove all the brass and lead plugs from the main well. Those are the accel pump inlet and discharge checks. The main well I'm sending you already has those inside.

Yes, the manifold gasket has a hole that is not used on a Scout 80. And the only holes in the flange on the throttle body other than the two mounting holes are also not active on that manifold interface. The gasket will seal those ports. This kit is used on many variations of these carbs, including Ford apps which use a vacuum-modulated "spark" control valve in the throttle body which the Scout 80 does not use...part of that circuit in your carbs should be plugged with either a brass plug or a thread-in plug.

#62 jet is correct for those carbs oem when used on the 152 app. For the altitude referenced, I'd jet it #60 and give it a try. I'll enclose a #60 and #58 jet in the package with the fresh economizer so you will have one of each to try.

 

[brained]

Economizer is in. #58 jet on it. Accelerator pump on long stroke (mostly cause the accelerator pump linkage wants to interfere with the throttle body and I didn't want to pull the carb off again to sort it out).

First impressions: took it for a test drive out at the local ohv and was able to pull grades in second that had required first before or had nearly stalled in second. A very slight stumble for just a second on hard acceleration when starting from lower rpm's.

Mm if you could layout the first steps of tuning I'll start working on it throughout this week. Thanks.