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lonewolf900

1929 Buick Standard Marvel Carb - Will Only Run With Choke

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My 1929-27 Buick Standard with Marvel carb will only run with choke on

I have had the carb apart numerous times, the jets are clean, I am using a large fuel filter, float level looks good, I have sprayed with WD40 looking for vacuum leaks.

Any ideas?

Thanks!!

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Hmmm, don't know why I'm jumping in on these older Marvels, choke on, full ? Heat Riser holes ? You say float level looks good, I would re-think that as I;'ve said the same. It seems the float level is perfect when it runs perfect and that depends on the car, IMHO. Marvels seem to have a mind of their own. A hair readjustment , sometimes is all it takes. Tons of other factors, like warped pot metal.... etc. Just takes time, eventually it will run with a Marvel, without burning down. Jets clean, really clean etc. Lot of brain damage.OCM

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The steel tube within the cast iron "Heat Riser" is often rusted through and allows exhaust into the intake.

I suggest you check that first...

Do a search for other posts on Marvel carbs...

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Other than the heat riser tube, you have a plugged metering jet or jets. It does not take much. You need to run a appropriately sized wire through both the short and long metering jets. Pull them out of the body and try to blow into them. You will soon find which one is plugged. Compressed air may not dislodge the the blockage. I also use carb cleaner spray to finally get all the gunk out of them.

Here are pics of my carb. You can see the debris in my bowl. It does not take much to muck up the carb. You can then see both metering rods. Make sure they still both have their red fiber washers. You can see the debris on the top of both metering rods. I had just cleaned the carb three months prior. Debris will find it way into the carb even if you have a sediment filter.

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Thanks for replies!! I have removed rusted out heat riser tube and plugged with freeze plugs. After initial carb cleaning, the engine ran well, then went to the condition of needing full choke to run I will pull carb again and clean jets, passage ways and double check for fiber washers.

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Just remember to plug the hole behind the riser tube to the exhuset too(that`s the way it goes in to the inlet).You can use a 1/16 copper plate.Then it will work well for the rest of your live.

Leif in Sweden.

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On 8/1/2013 at 12:49 PM, lonewolf900 said:

Thanks for replies!! I have removed rusted out heat riser tube and plugged with freeze plugs. After initial carb cleaning, the engine ran well, then went to the condition of needing full choke to run I will pull carb again and clean jets, passage ways and double check for fiber washers.

Hi Lonewolf

Did you ever get to the bottom of this as I'm having the same issue and have worked on the car for 3 days now but still need the choke to prevent it from backfiring into the carb. 

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