Zenith wizardry in TN/KY

[70roundtail02]

Looking to see if there is anyone between about Louisville and Nashville that could provide some instruction/mentorship on tuning the Zeniths on the Bristol RHD.

I’ve addressed and fixed a couple issue (vacuum and fuel) but still having trouble getting it to idle. The carbs don’t seem to the idle cut off solenoid, the spare set in the trunk does, but the mourned ones don’t.

Getting good fuel and spark, if i fill the carbs it will fire and run. It will continue to run under throttle but the second it drops down under 1k on the rpm’s it dies.

Appreciate any help info or guidance.

 

[YoAdrian]

I've had issues with it dying when the fuel line was old/loose causing the fuel pump to suck air. Another potential is the diaphragm inside the mechanical fuel pump -it is known to leak when the rubber ages and can struggle to provide enough fuel.

 

[stphers]

If I understand this right, both electric idle jets are not working on the carbs? to check them, make sure that there is power coming to them. It is easy to accidently ground one out and the fuse blows, check them as well. to check them, take a 12v source ( battery ) and after removing the idle jets, attach a wire between the terminal end of the jet and + on the battery and just ground out the case to the - post. It should click quite loudly ( opening solenoid inside the jet ) If all that works, blow out the idle circuit and make sure that with the choke off, the idle set screw is opening the throttle a bit and then try it

Thanks, Rick

 

[70roundtail02]

These carbs don’t seem to have the electric idle jets. Wondering if I’m getting a vacuum leak somewhere.

 

[stphers]

Is there a std jet in it's place?

 

[70roundtail02]

It appears so down in the base on each side. I’m going to spend some time working on them this weekend. With a little fuel in the bowls the car kicks over instantly. Keep the revs off idle and it will run just fine.

I think one of the water chokes on the front carb is off. They should be closed in the cold start position correct?

 

[stphers]

Yes, the choke butterfly should be almost completely closed when cold. There should be a small gap ( about 4mm ) clearance so some air can get in.

Thanks, Rick

 

[70roundtail02]

Got that sorted, now wondering if there are actually some disconnected vac lines. Base of the carbs drivers side. The front and rear are “Tee’d” together but then it’s connected to nothing?

 

[deQuincey]

Yes, the choke butterfly should be almost completely closed when cold. There should be a small gap ( about 4mm ) clearance so some air can get in.

Thanks, Rick

It should be completely closed
no gap at all
when you start the engine the vacuum produces the gap that is stated by the adjacent membrane and its limiting screw

 

[deQuincey]

Got that sorted, now wondering if there are actually some disconnected vac lines. Base of the carbs drivers side. The front and rear are “Tee’d” together but then it’s connected to nothing?

Must connect to the air filter
or capped

post pictures, you might have a mess of biblical proportions

 

[Stevehose]

Got that sorted, now wondering if there are actually some disconnected vac lines. Base of the carbs drivers side. The front and rear are “Tee’d” together but then it’s connected to nothing?

Cap all of them if not running distributor advance

 

[Stevehose]

It should be completely closed
no gap at all
when you start the engine the vacuum produces the gap that is stated by the adjacent membrane and its limiting screw

Secondaries should have some clearance to avoid binding - I forgot the spec - perhaps .1 mm?

 

[deQuincey]

Cap all of them if not running distributor advance

Talking about different hoses, my think

but essentially Is ok

 

[70roundtail02]

So I’ve capped the two lower ones on driver side (passenger because car is RHD) but will refer to it as if it’s normal driver side being left.

On the passenger side the front carb has one line going to the distributor. Car is running a UK/ based lumenition ignition system. The same port on the rear carb is capped off.

The knurled screw at the base of the carbs passenger side what does it control?

 

[deQuincey]

So I’ve capped the two lower ones on driver side (passenger because car is RHD) but will refer to it as if it’s normal driver side being left.

On the passenger side the front carb has one line going to the distributor. Car is running a UK/ based lumenition ignition system. The same port on the rear carb is capped off.

The knurled screw at the base of the carbs passenger side what does it control?

do you have stock air filter ? If yes why Capp the hoses ?

knurled screws are iddle screws

do you know how synchro ? And tuning ?

 

[deQuincey]

Some knowledge

Lan-Engine M30B30 tuning thread, steps, values, specs, and so on

Planing to do this complete process. please help and feel free to contribute it will involve: 1- VALVE CLEARANCE ADJUSTMENT 2- IGNITION 3- CARBURETOR TUNING AND SYNCHRONIZATION 1st- VALVE CLEARANCE ADJUSTMENT 10 N.m is the torque that should be applied to the securing nut...

e9coupe.com

Here also videos

LAN my renewed engine M30B30 Running in process

Howdy. This is the kind of things that i do best, providing useful hands-on documentation for people that love the emotion to have dirty hands and white smiles in their faces while taking care of their e9 coupes or e3 sedans I take the information comming from the blue books, and bring my own...

e9coupe.com

worth a watch

 

[boonies]

link to some published resources, the links to carb info is the fourth topic down.

Published Sources

e9coupe.com

 

[70roundtail02]

link to some published resources, the links to carb info is the fourth topic down.

Published Sources

e9coupe.com

Oh many this is super helpful. I somehow had missed this

 

[70roundtail02]

 

[70roundtail02]