TEA20 Governor Bumper spring

What are the symptoms of one of these breaking or losing it's spring?

Reason I ask is my '48 has always run really nicely with no surging. Couple of weeks ago it started stumbling and spluttering whilst using a topper. Lots of surging and eventual stalling.
It would barely run above idle. Turned out there was a grass seed stuck on the needle valve which was blocking the fuel flow almost completely so you had to let it idle and fill the bowl before it would run faster for a few seconds.

Once I fixed that and went through everything else it ran fine up to about a 1000rpm but then went into a mad surge cycle.
I've never messed with the governor as it never needed it but despite checking and rechecking the adjustment it still surged if the adjuster was set to just touch or to the 1-2 turns after touch I've read about.
The only way to stop the surging at higher revs or under load is to screw in the adjuster probably 5 turns.
That seems to cure the problem. (I presume this effects it's operation at lower revs)

Back it off and it will start surging again whether under load or not.

I'm wondering if the earlier surging and governor pulsing has put too much strain on an old spring and either flattened it or broken it partially?

Is there a way of telling without stripping the front of the engine?

With governor to carb rod disconnected it runs perfectly at all revs.

So it sounds like you have fixed the problem by turning in the Governor needle screw. You probably just have worn Governor parts, not a
spring. So turning in the limiter screw has fixed the problem as of now. In time you may want to pull the front off and replace/rebuild the
Governor to new which would then have you back out the adjustment to operate properly.

Check the ball joints at the top of the governor/ throttle linkage , these can stick or become.e so loose that they cause surging .
If the spring is broken it can be replaced with a piece of industrial hacksaw blade , it needs to be riveted on , I haven't seen them available as spare parts .

Yes it seems so, there don't seem to be any adverse effects to having it wound in further.
I've just been reading the workshop manual online and it mentions starting with up to a turn after contact but more turns to stop surging if required, doesn't refer to a maximum so as you say maybe everything is just worn and the recent problem has brought that to light more.


This post was edited by NKirov on 06/26/2022 at 12:28 am.

Ah that's interesting, I couldn't find it as a spare either which makes me think it's probably very rarely required.

A job for the future maybe at rebuild time!

If it's still giving problems, try this:

Back the bumper screw off. Set the dash lever to idle. Check the throttle at the carb. It should be held
tight against the idle stop screw. If it is loose, adjust the rod from the governor arm to the carb ever so
slightly so the throttle is against the idle stop screw.

Doing so takes the governor out of the picture at idle. You don't need it at idle, and it will try to self
correct resulting in surging. That's all the bumper spring does is limit the travel of the governor, but you
want all the travel you can get for it to work properly. It's really not even needed.

This will not change the governed RPM, that is done with the U bolt up above. You need a working tach to set
that, about 1300 RPM.

If it still tries to surge off idle, try a partial choke. If that stops it, the mixture is too lean.

The idle mix has very little effect on running, but adjust it anyway. The engine must be at very slow RPM,
down around 400 for it to have ant effect. Turning it out leans, in richens. It adjusts air bleed, so it's
backward of what modern carbs do. If it has no effect there is a blockage in the idle circuit.

Go ahead and try adjusting the high speed. To set it, idle the engine down, then soddenly open the throttle.
It should take sudden throttle without stumbling. Keep leaning the main until it stumbles on acceleration,
then back it out 1/4 turn at a time until it takes throttle without stumbling, a single puff of black smoke
is acceptable.

Of course all this is dependent on a properly tuned and healthy engine. If it's not tuned, points out of
adjustment, timing off, worn distributor, stuck advance... It won't run right with a perfect carb.

Same for compression, tight or leaking valves, vacuum leaks, clogged air cleaner mesh... Everything works
together!

A really simple and thorough explanation Steve .