Cannot slowdown tickover

[A7novice]

Advice Please.
I have just rebuilt engine for 1933 RP.

Runs very well etc except for two minor problems.
I would welcome any suggestions from people more experience and knowledgeable than myself regarding these two issues.

1) The tickover is a little too fast. The slow running stop is screwed so there is no contact with the operating leaver, ie that is not the cause of the fast idle. Similarly, when choke is fully off, the screw that bears on the choke leaver that opens the throttle is also not in contact, so again, that cannot be the cause of the fast idle.
The only way I can slow down the tickover to a more reasonable speed is by retarding the ignition to almost TDC
Any ideas?

2) When revving fast, there is the (very) occasional spit back through the carb.
The plugs appear black, not wet, not sooty.
Again, any ideas how I can remove the spitting problem?

best regards
A7novice.

[Thowdfella]

Advice Please.
I have just rebuilt engine for 1933 RP.

Runs very well etc except for two minor problems.
I would welcome any suggestions from people more experience and knowledgeable than myself regarding these two issues.

1) The tickover is a little too fast. The slow running stop is screwed so there is no contact with the operating leaver, ie that is not the cause of the fast idle. Similarly, when choke is fully off, the screw that bears on the choke leaver that opens the throttle is also not in contact, so again, that cannot be the cause of the fast idle.
The only way I can slow down the tickover to a more reasonable speed is by retarding the ignition to almost TDC
Any ideas?

2) When revving fast, there is the (very) occasional spit back through the carb.
The plugs appear black, not wet, not sooty.
Again, any ideas how I can remove the spitting problem?

best regards
A7novice.

---

I have had similar problems recently with my Zennith carb. Also being very difficult to start. I found two very small holes blocked. One behind the progression jet which is on the body of the carb. The other one is at the top of where the slow running jet screws in. I also replaced all the gaskets whilst doing it and it now runs very sweetly. Other than that I would start to look for aur leaks as you have just had the engine down. Good luck.

[Reckless Rat]

If your car has a Zenith carb it may be drawing air at the carb to inlet manifold flange. It's a regular problem due to the soft alloy the carb is made from.
Take the carb off and rub the flange on some emery paper on a hard flat surface.

Either that, or the throttle spindle is worn. (also a regular)

[A7novice]

Thanks very much for both suggestions, I will investigate both suggestions later in the week.
Might be a simplistic question but... can you use sealant to help seal carb/inlet manifold joint (after first trying to true up carb flange), eg a copper based sealant as used on cylinder head gasket.

[Martin Prior]

If your car has a Zenith carb it may be drawing air at the carb to inlet manifold flange. It's a regular problem due to the soft alloy the carb is made from.
Take the carb off and rub the flange on some emery paper on a hard flat surface.

Either that, or the throttle spindle is worn. (also a regular)

I'd put a worn throttle spindle at the top of my list.  Try shutting the throttle further by directly turning the arm on the end of the spindle and at the same time check for unwanted movement.

[Reckless Rat]

If the mating faces of the manifold and carb are flat then there should be no need for jointing compound - the gasket itself should suffice, but belt & braces can't hurt if it makes you feel better - I use Loctite 5290.

[Tom the Blacksmith]

You can use hylomar or similar fuel resistant compound to seal the carb/manifold joint. One of the few places I use hylomar.

Tom

[John Mason]

I had problems of slow running on my Ruby. The problem was resolved by cleaning the small jet that comes out into the ventora tube just below the throttle butterfly. It's purpose is to allow a small amount of air to enter the carb when the throttle is closed.
I however am not sure if this is the model of carb fitted to your seven.

John Mason

[A7novice]

Very many thanks to all folks who took trouble to reply to my request for advice.
It will be a week or so before I can work through the suggestions, I have removed the flywheel prior to relining clutch.