Zenith Carb. Issue

[stevests]

Which passage or jet might be plugged that only lets the engine run on near full choke ? Appreciate some guidance.

[Brentwood Bob]

Does gav have any affect?

[larrys40]

Look for a plugged cap and/or main jet.
Today’s fuels will gel fairly quickly if not run now and then.
They are the two jets that are in the Venturi opening when you separate the halves
Larry shepard

[stevests]

Thanks fellas' - it sat with pump gas for some time. I disassembled it completely & soaked it in carb. cleaner - looked clean but no go ! I can check the GAV but I set it at 1 & 1/2 open to start- starts up right away but needs near full choke to keep her running.

[1crosscut]

You don't mention if you used compressed air to blow the passages and jets out. If not I would suggest soaking again and blowing them out.

Possibly an intake manifold leak too. Check the tightness of the manifolds.

[Patrick L.]

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Just take it apart and soak it again. Use torch tip cleaners or a straightened paper clip and scrape out the passageways as best you can. Then spray thru them with Deep Creep spray [ or choke/carb cleaner] and finish off with compressed air.

[30 Closed Cab PU]

Possible worn Throttle Plate Shaft/Bushing? Check the shaft to insure it fits snugly in its bushing. Have heard this is also a source of a whistling noise.

[1931 flamingo]

Vac leak either at the manifolds or where carb attaches. JMO
Paul in CT

[stevests]

This was a new repro Zenith - I'll double clean & use the above suggestions - thanks !

[30 Closed Cab PU]

Since it was new, before messing with it much, call the vendor. They may have suggestions, and if it turns out to be the carb, a good vendor would want to be involved in case they want to exchange it. Once you have messed with it much, they may not want to exchange it.


Do you have access to another carb known good you could try?

[stevests]

Already replaced with the Zenith the car came with after I replaced the throttle shaft on it - it runs fine. The "new" one was in a box that the fella got with the car - the car had been sitting a while & who knows when the replacement carb. was purchased !

[30 Closed Cab PU]

another option in case a good cleaning does not work. Try swapping in a flow tested jet kit, Renner's Corner is frequently mentioned om the FB as having good flow tested jets. Is not expensive.

[larrys40]

Correcting my post to say Dave Renner is still supplying flowxtested jets, just not rebuilding carbs any longer. It’s amazing by flow testing you can realize not even all jets point the stream of flow straight . Highly recommend flow tested jets if you can.
Special thanks to Dave Slater for updating me.
Larry

[Dave Slater]

Larry I think you have that slightly wrong. Dave Renner STILL sells flow tested jets for the A&B carbs. He just does not REBUILD carbs anymore. Dave

[larrys40]

Originally Posted by Dave Slater

Larry I think you have that slightly wrong. Dave Renner STILL sells flow tested jets for the A&B carbs. He just does not REBUILD carbs anymore. Dave

Ok that is good to know... I spoke to him last year and he said he didn’t do any of them any more when we spoke last year. It sounds like I misunderstood . Good to hear he’s still supplying flow tested jets. I do my own and know he and I were mainly talking B carbs. I will fix my post.
Thanks for the update.
Larry