• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

carb question

Share this page

walshja

walshja

Jedi Warrior
Offline
I have twin SU carbs, and the plungers keep unscrewing on me.

If I tightne them too much, it seems like I go past the point where it hold, and I have to start all over again.

Wondering if anyone has this problem? and a solution !!

joe
 
Plunger?
 
If I understand what you're saying, when you try to tighten them they never really get tight and will turn forever. Sounds to me like the plastic threads are shot. New ones are available. (Doesn't really matter what you call them)

Marv J
 
the threads are fine, and it tightens fine.

but, if I keep turning them, they will pop out of the threads, but I can get them to a point where they shouldn't be backing out. I can really get them tight, but after a few trips out in the car they both loosen up and unscrew completely and are bouncing around.

weird . . .

joe
 
If you "keep turning them and they pop out of the threads," it sounds like the threads aren't fine and it's not tightening fine. They may look OK, but if they don't hold, they are not right. The threads on the plastic caps do wear and then they get loose easily. Easily fixed; just replace them. The threads in the carb body are probably OK.
 
No-one has mentioned: they ~should~ have fibre washers between the carb and the cap as well.
 
And if the threads on the plungers (dampers) are fine...how do the threads in the chambers look?
 
The set of Carbs I purchased on eBay and just finished rebuilding had thread locking lock tight on the dampers. After removing the loctite they acted as you described. A little loctite may get you by. Another thing I noticed was the throttle shafts were worn and the PO used JB Weld on the ends of the shafts to stop air from leaking in. Naturally I have rebuilt them with new parts but I thought that was some low cost quick fixes that are quite clever.
 
Back
Top