For the record the stock zenith gets advance vacuum from the right front corner of the frontcarb above the throttle plate, retard was hooked to rear carb on driver side under the throttle plate with manifold vacuum.
Ignition timing questions.
- Thread starter Larry Louton
- Start date
Mike Goble
Well-Known Member
My vacuum advance connection. Lots of advance at low load conditions makes the engine run cooler.
Hello to all, To Dick Stienkamp, On the charcoal canister question, So the two pipes from canister, one goes to the fuel tank and the other one goes to the fitting under the air filter housing? OK, I can correct that. Sure wish I had a vacuum schematic. When I first started setting the timing on this car the vacuum advance was hooked up to venturi vacuum. The company said that it should be hooked up to manifold vacuum. So I set the ignition timing accordingly. Vehicle still surges at low speed. This is the distributer that came with the car, What ever vacuum advance mechanism program it has is the one I have been using. If it has a programmable curve? Perhaps that is what it needs. I have ports for either manifold vacuum or venturi vacuum. Both carbs are on the bench ready to be disassembled, cleaned and measured. More on this later.
Thank you for your insights.
Larry Louton
Thank you for your insights.
Larry Louton
No vacuum of any kind for tuning - cap all ports at carbs (2 each). It appears you have the early switched version of the 123, unscrew the hex cap on the side of the dist and take a pic or tell us the setting on the micro switch position. Don't sweat the cannister either until your engine is running well.
Yes. But not directly to the fuel tank. That pipe goes to the plastic accumulator container on the right side of the trunk between the wheel well. and the fender. From there to the tank. If you had this hose hooked up correctly and the other hose coming out of the charcoal canister hooked to the intake manifold vacuum port, that would account for the "whooshing" sound when you opened the gas cap. It was trying to create a vacuum in the tank and at some point would have probably stopped fuel flow to the carbs.
As Steve indicates, this is not that important at this time as long as the charcoal canister is not hooked up to manifold vacuum and the fuel tank is able to vent.
Hello all, As I explained in the beginning, The vacuum hose to the canister from what I thought a welded up fitting on the intake was capped off with a golf tee. I fixed the welded up fitting and attached a new hose to my new port. Dick says this wrong it should go to a fitting on the under side of the air filter housing. I will correct that tomorrow.
Steve, I removed the cap/plug on the distributor and the pointer is on the letter "A". One carburetor is nearly done, The nuts that hold the carb to the manifold were all loose.
The nuts that hold the primary carb linkage were loose. The float level was at 45mm. I saw a thread that I can't find momentarily about plugging the vent for the power valve.
It's here, somewhere.
Thank you.
Larry Louton
Steve, I removed the cap/plug on the distributor and the pointer is on the letter "A". One carburetor is nearly done, The nuts that hold the carb to the manifold were all loose.
The nuts that hold the primary carb linkage were loose. The float level was at 45mm. I saw a thread that I can't find momentarily about plugging the vent for the power valve.
It's here, somewhere.
Thank you.
Larry Louton
Correct...as long as you mean charcoal CANISTER and not vacuum advance CANISTER.
Be sure that new port in the intake manifold is plugged.
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Hello, Just did a fuel pump volume test before installing the carburetors. While cranking, two psi and about 3/4 of a pint in 30 seconds. Sufficient?
Thank you
Larry
Thank you
Larry
More than sufficient.
3/4 of a pint in 30 seconds is .094 gallons in 30 seconds. That would be 11 gallons/hour. Obviously with the motor actually running and driving much more fuel than that would be supplied to the carbs, but if you went 60 MPH using that much fuel you would only be getting 5.5 MPG. You probably use less than a teaspoon every 30 seconds idling. If you did the pressure test with the fuel line open (not connected to the carbs), the measured PSI would be lower than when the fuel system was assembled with the carb float bowls full.
3/4 of a pint in 30 seconds is .094 gallons in 30 seconds. That would be 11 gallons/hour. Obviously with the motor actually running and driving much more fuel than that would be supplied to the carbs, but if you went 60 MPH using that much fuel you would only be getting 5.5 MPG. You probably use less than a teaspoon every 30 seconds idling. If you did the pressure test with the fuel line open (not connected to the carbs), the measured PSI would be lower than when the fuel system was assembled with the carb float bowls full.
Hello Dick, Before I put the carburetors back on, I was looking at maybe a low volume/ lean condition. I did get the car started and tuned/ synched somewhat. The idle has improved, Both mixture screws work now, The stutter and violent hesitation is gone. Tomorrow I will be settling on the proper ignition timing and choose to use the manifold or venturi vacuum. I really didn't find any thing wrong with the carbs except that all the flange hold down nuts were loose. But they sure are clean now.
Thank you for your time.
Larry Louton
Thank you for your time.
Larry Louton
Larry. I know only enough to be dangerous 
@Stevehose is an expert on the 123 Dizzy (and many other M30 topics). @HB Chris has forgotten more than I will ever know about these motors. @Mike Goble is an all round great mechanic with lots of time with Bavarias. There are plenty of other guys here with lots more knowledge than I have.
If you think you are close to having the carbs dialed in, let Steve lead you through setting up the 123. Take him up on his offer to work with you on getting your car running right. Re-read the article Mike linked to. Venturi vacuum does not play a role in this issue. Your choice is manifold vacuum or ported vacuum. You are getting plenty of fuel to the carbs. It's still possible to have a lean condition, but it's not due to lack of fuel.
@Stevehose is an expert on the 123 Dizzy (and many other M30 topics). @HB Chris has forgotten more than I will ever know about these motors. @Mike Goble is an all round great mechanic with lots of time with Bavarias. There are plenty of other guys here with lots more knowledge than I have.If you think you are close to having the carbs dialed in, let Steve lead you through setting up the 123. Take him up on his offer to work with you on getting your car running right. Re-read the article Mike linked to. Venturi vacuum does not play a role in this issue. Your choice is manifold vacuum or ported vacuum. You are getting plenty of fuel to the carbs. It's still possible to have a lean condition, but it's not due to lack of fuel.
Larry - just to reiterate, I would ignore vacuum advance on your initial install and concentrate on your idle and transition first. You want to make sure you are not introducting too many variables at one time