Zenith Carb Choke Plate screws stripped

[Wuudie]

They won't budge.

Used PD Blaster for last couple days-spraying each screw twice a day. Did the Throttle plate Screws, and the Choke plate Screws.

Throttle plate screws came out
Choke Plate screw can't even get the screw driver in to bite anything.

Can't get the drill bit in straight to get them out.

Suggestions?

[Fordlane Wayne]

I've used a center punch to get a drill started, then used a small drill to begin followed by a drill size that is close to the screw size. The throttle shaft will be useless because you'll destroy the threads, but if careful you can save the throttle plate. Good luck.

[dave in australia]

The screws are normally peened over so they'll need more than penetrant. Try filing the thread ends.

[Tom Endy]

heat the heads of the screws with a torch until they are cherry red then dunk the carb in a bucket of cold water. The screws should then easily unscrew. This is the secret of disassembly of other Zenith parts frozen together, especially the brass parts.

Tom Endy

[Dave in MN]

I can picture your problem....
Try heating the shaft and plate with a propane torch. Get it pretty hot and then apply paraffin wax to the screw. Apply additional wax as it continues to cool...at the correct temp, it may pull some of the wax into the threads. If it pulls it in, the wax will lubricate the threads. Let it cool completely before you try to remove the screw. Try to refresh the screw slot with a file...you won't have much to work with.
If the previous method won't work, do you have a die grinder? If so, a small carbide tipped burr would remove the screw head allowing the removal of the plate. With careful work, after the plate is removed, the screw could be taken down to allow the removal of the shaft from the carb body.
After the shaft is removed, you could grind, drill and re-tap the shaft. Or you could look for a donor shaft for the choke assembly rather than attempt the last bit of work.
Tom Endy's method works good also...but I'm always a bit fearfull of the cold water dunk of the surrounding cast parts!
Good Day!
Dave in MN

[dave in australia]

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Just been informed that they're not normally peened, but I'd still try filing the thread ends anyway. It's always worked for me, I've never had to drill a screw in the carb or apply heat yet, but Ive only disassembled around thirty or so carbs.

[Dennis L Oberer]

Take a small hack saw blade and saw off the choke shaft on each side of the plate (it usually can be slid back and forth). and junk the parts and replace with a new choke shaft and plate.

There is a lot of moisture for some reason in this area that gets these screws good and rusted tight.

Most choke plates that I have seen are rusted and pitted because they are steel; while the throttle plate is brass.

Any looseness in the shaft to housing isnt important as it does not affect the engine running like the throtte shaft fits.

Dennis L Oberer
Green Bay WI

[Wuudie]

Please note- when you put a torch to it, make sure you clean the spider webs from inside the carb - spider webs are very flamable.

I did the drill bit, solution
Even after I drilled out both screws, and the peice of arm between the two bolts fell off on both sides the plate was still stuck, I had to use needle nose to pull it out. Once I pulled it out, I pushed both arms in so not to scar the sleeve

Plate is totaled.

Thanks all

[Tom Wesenberg]

Originally Posted by Tom Endy

heat the heads of the screws with a torch until they are cherry red then dunk the carb in a bucket of cold water. The screws should then easily unscrew. This is the secret of disassembly of other Zenith parts frozen together, especially the brass parts.

Tom Endy

Yep, this method always works for me, and it only takes a propane torch.