Bent Throttle Shaft

[dennisv]

It appears to me we have a bent throttle shaft. Is it possible that I would have success just replacing this shaft with a new one? Or is this merely a symptom of a more serious issue that needs professional attention?

I started rebuilding our Zenith 40 TIN carburetors. I thought I was just cleaning and replacing gaskets. Perhaps some jets. Removing the enrichment feature. I've torn down one carb. I noticed that the throttle plates would not return to closed by force of the shaft return spring alone. Above half way there is a bit of resistance. Investigating that, I found two bent throttle plates and now it appears the throttle shaft is bent too.



Not sure where to go from here...

[Nditiz1]

I believe Klassik automotive school replaces both the shaft and butterfly plate when doing Webers. This might be a case for that too unless the butterfly's are also fine. You can just buy new shafts and install them.

[dennisv]

Originally Posted by Nditiz1

You can just buy new shafts and install them.

That would be great. I guess I'm trying to understand what could cause the throttle plates and shafts to get bent in the first place.

[Flat Six]

Originally Posted by dennisv

That would be great. I guess I'm trying to understand what could cause the throttle plates and shafts to get bent in the first place.

Backfire, probably

[E Sully]

I wonder if trying to just replace them would work. Trying to remove bent shafts might damage the bores that it passes through, if they are not already damaged from the force that bent them.

[Nditiz1]

Good news if the bores are ovaled new bushings can be installed.

[digitaldgp]

I had my Zeniths rebuilt by Dave Cheney, they are a work of art!!
He line bored the throttle shaft bushings and installed new Oversized shafts, couldn't be more happy with now. I also had him upgrade my carbs to Sport, 32mm venturies and etc.

https://www.dccarburetorrestoration.com/

[porschedude996]

I’ve straightened shafts on DRLA Dellorto’s and Carter AFB’s and had great success.

[snbush67]

I think that the shafts can be bent by unequal and over torquing the carbs to the manifolds.

[snbush67]

Originally Posted by digitaldgp

Are the top gaskets in the right place? It seems they should be under the filter base.

[Nditiz1]

Possibly, on the Zeniths I just sold the K&N base plates had a slot for the gasket on top between the stacks and the base. These don't look like that type and should probably go underneath.

There is also an argument for both top and bottom unless it could be proved that the stacks to the base plate are perfectly flush.

[digitaldgp]

Originally Posted by snbush67

Are the top gaskets in the right place? It seems they should be under the filter base.

I had extra's so I installed them on top of and under the air filter plates.

[Nditiz1]

Perfectly acceptable especially since I have actually seen where flow through the syncro was off due to air being sucked in below the stack as the stack had been over tightened creating a gap. Tip: balance carbs with base plates and stacks removed in order to get correct readings at the top plate.