Zenith Wont Idle

[DesignerV]

Well, This morning I went out and checked, set and rechecked the Tappet Clearances, with the engine hot. It was fun, but it seems to run about the same. I will probably check them again soon.

Then I thought I'd have a look at the spark plugs. I found that they are all Bosch Super RO's, but they each have different numbers on them. Two are 562, one is 662 and one is 371. I'm not sure what this number means, but it's odd to me that they'd be different. So, for my next trick, I will replace them all with Champion RN11YC or NGK BP5ES plugs.

Here is a vid of how it runs today, seems a bit out of time, with some pops and chuffs.
Thoughts?


Have a good weekend everyone!

[darbsclt]

Hmmm... that does sound a bit choppy...

Suggestions...
- Depending on when you last did it... tackle some of the easy, routine maintenance stuff first (just to eliminate them as possible culprits, or having them compound symptoms). By that, I'm talking Plugs, Wires, Rotor, Cap, etc.. I think I recall you having an electronic ignition... so gap your new plugs appropriately for your unit. Also, if you don't know how old your coil is... it may be time for a new one.

- Next I'd focus on timing. Fortunately, I've never had to muck about with mine... but my understanding is that on Series rovers (depending on the engine's age and history) it can be more of an art than science. Some folks over in the UK at the Series 2 Club (HERE) swear by the "Pint Method"... whereby a pint of your favorite ale is set on the wing and the distributor is adjusted slightly - to the point when the engine smooths out and causes the least disturbance in the glass. Even if it never smooths out - you still get rewarded for your effort.

- Since I'm also no help with Zenith Carbs ( I have a Rochester)... I, again turn you towards the Series 2 Club. A quick search on their forum reveals a wealth of experience & they are a helpful bunch.

Good Luck!

ps... nice vids! - they are a great way to illustrate an issue.

[DesignerV]

Hey thanks!
With cell phones and computers now it makes it easier to post pictures and videos than to describe with words!

Replaced the plugs today with a set of NGK BP5ES. No change in the running, but at least I know what's in it now...
I looked at the coil based on your suggestion, its an Accel 8140C. Not sure if that's quite the right one for this setup, so I may look at what should be paired here. (I'm already in way over my head reading about this stuff )

Thanks for the forum referral, will start poking around over there too!

I'm starting to think the Carburetor isn't even the issue anymore. Perhaps this should have been apparent sooner, but, had to start somewhere. I have a feeling that the previous owners never quite got all the electronic ignition and engine timing dialed in.

Once I figure this out, I'll put a few pints over on the wing! Sounds like a good method!

[DesignerV]

Well,
This morning I attempted to reset the timing, and, at least I don't think I made it much worse. I started by lining up timing mark on the pulley between the 3 and 6 deg BTDC mark, for the rotation when the rotor would be hitting the contact for cylinder one. Then I adjusted the optical sensor to just barely be triggering at this point. So, I think this is the basic equivalent of setting static timing for electronic ignition...

Then I manually rotated the distributor both directions in tiny increments to gauge the response. I got it to raise the RPMs by advancing the timing a bit, but slowly adjusted that and lowered the idle speed/reduced the choke. Made a tiny bit of progress, but overall it's not running any better, and I'm a bit worried that I could be causing more issues if it is messing with the mixture. Now though I want to try fiddling with the idle mixture screw and see if that makes a difference. I forgot to try that.

After being frustrated with that, I changed the oil.

I also ordered a vacuum gauge and a compression tester, when those arrive and I have a chance to try them out, I will update this thread.

Something I did notice today, was that at some times the level of fuel in the fuel filter is very low. I figure this might be because the carb floats are keeping the needle valve closed and the system is just building up pressure. When I rev the engine the level will rise. Does this look normal?



Thanks everyone, enjoy the rest of the weekend!

[darbsclt]

I'm no expert... but that fuel flow doesn't look right to me. It almost looks like you are pumping air.
I assume you are running a stock mechanical pump...?...

- Do you smell fuel?
- Have you checked the tightness of all your hoses & pump fittings?
- Have you connected a pressure gauge to the line? Is the pressure good & consistent?
- You might try disconnecting the fuel line from the carb & submerging it in a mason jar of fuel - then crank the engine - see if air is being pumped with the fuel. It's possible to have air enter the system without fuel leaking from it. If so, you might need to rebuild the pump.

Just some random thoughts...