1929 Master engine won't run

[Rooster]

I'm helping my widow friend with her 1929 Roadster 121.  I try and keep on top of things by taking it for a drive now and again.  It sat for some time and I could not get it to start.  Drained old fuel and put fresh stuff in, still nothing.  No fuel getting through so I changed out the pump and inline filter.  Managed to get it to fire and run on full choke but when push the choke in it stops.  I'm now down to thinking there is a blockage in the carb. I don't know anything about the original because my 1929 Standard is converted to a down draught and has run flawlessly for 30 + years. I don't want to upset the settings on the original carb so reluctant to pull it off but will if I have to.   Just asking here is there anything else I should look at before doing so.

Edited February 25 by Rooster (see edit history)

[Roger Barrett]

One possibility is the thin steel sleeve in the Marvel heat jacket between the carburetor and intake manifold is rusted through which creates a vacuum leak that can’t be diagnosed with conventional methods. It will drive you crazy trying to get the engine to run. The only way to investigate it is to pull the heat jacket of and inspect it, trying to punch holes in it with a pick.

[Rooster]

It is driving me crazy Roger.  If I end up taking the carb off will check that sleeve for sure.

[raydurr]

More than likely carburetor blockage. If your car has the original carb be aware that it is super fragile. They crack very easily. The potmetal used was about as bad as it gets. Heat riser sleeve is a possibility. As far as the settings, you can always count the turns, as you screw the settings in to bottom,then record. I can usually reuse my gaskets each time. If not they are easy to make. I check the flapper clearances and movement while I am in there. Occasionally a float will no longer float. I dont adjust the float unless necessary.

Edited February 25 by raydurr (see edit history)

[Hubert_25-25]

Ken, 

    Did you let the car warm up?  Old cars have 2 hand adjustments.

Choke - should only be used for a cold start.  Once the engine has started, it needs to be open.  Failure to do so will foul the plugs. 

Throttle - This is necessare to keep a cold engine running.  Expect to use an increased throttle off idle for around 5 to 10 minutes. 

 

Before touching the carburetor.  Use some fine emory paper and clean the points.  Check the gap.  The easiest thing to do is set a dwell meter on the car to verify the point gap. 

 

Here is an article to take you thru rebuilding and checking the carburetor and the heating system.   

https://forums.aaca.org/topic/372573-1920s-buick-marvel-carburetor-rebuilding/#comment-2311177

 

Hugh

    

[28Buick]

Roger makes a good suggestion with the heat jacket. Perhaps check a few items before surgery.

1- Remove the float bowl cover (three screw flat cover plate) and see if the bowl has fuel in it. Push down on the float and you should be able to momentarily overflow the bowl. If the float does not float it must be replaced.

2- Thoroughly spray Gumout through the carb as it sat with old fuel for some time. 

3- Remove the low speed fuel needle (the big bottom wheel) to inspect and clean. Reset by fully seating and one turn open.

4- You said changed out the pump? Is this an aftermarket or is it the original vacuum tank? If original pour a few ounces of fuel into the vacuum tank, that should flow freely into the Marvel, or run the aftermarket to verify fuel flow to the carb.

5- Blow or push compressed air into the fuel line to the rear tank. Somebody with an ear over the open fuel cap should hear bubbles. Or pull a vacuum (suck) on the fuel line and only fuel should flow, no air.

6- You said inline filter? Where is this located and can it be bypassed? The glass bowl fuel screen should be cleaned. The bowl should have no crap in it.

7- If it is the heat riser Hugh posted excellent instructions on how to fix that with a bypass, modern fuel does not need to be pre-heated.

8- Here is a direct quote from Hugh's powerpoint: "There is a fuel filter screen on the plug on the bottom of the Marvel carburetor.  It is located below the fuel inlet.  Trash collects around the filter and the fuel travels up the center to the needle and seat.  The filter is to keep trash out of the jets.  On many Buicks, this filter is missing, as it may have been plugged and then removed to get the car started and never replaced.  The filter is Sierra part number 18-7832 or Mercury (as in outboard) 1399-3938. "

9- This technology is a Marvel, eh?

[Mark Shaw]

23 hours ago, 28Buick said:

4- You said changed out the pump? Is this an aftermarket or is it the original vacuum tank? If original pour a few ounces of fuel into the vacuum tank, that should flow freely into the Marvel, or run the aftermarket to verify fuel flow to the carb.

29 Buicks have mechanical rubber diaphragm type fuel pumps.  If the original diaphragm is still in the car with modern ethanol fuel, it will fail and put particles into the filter and carb.

[Rooster]

Looks like I'll have to pull it off next time I am around her place.    There is fuel getting to the bowl, I know that because the float was stuck and fuel went everywhere.  I warmed engine best I could but still won't run without full choke.  Didn't like to run it too long with all that fuel washing the piston wall.  It's frustrating because the engine has always run like a swiss clock.   Thanks everybody.

[Mark Shaw]

Also note that the air adjustment knob should be about even with the end of the ratchet spring as a starting place.