E3 2500 Zenith Cold Start Rough Running

The rear choke- adjust. It's rich if you look at the front. Slightly loosen the three screws and rotate clockwise 1/4" or so. Yes, adjust the flap slightly open. They should be even to each carb.

You say there's power to the electric chokes. I don't see it. It's usually a green wire and there's not a connection to either carb- the open spade.

I don't see idle solenoids either. You have early carbs.

The vacuum lines to the manifolds. there shouldn't be a Y connection. It's just a hose connecting the two. Where the Y goes I can't tell. But distributer is my guess. That requires ported from the other side of the carb not manifold pressure for early carbs.

Unfortunately, you can't use a carbmate unless you make up a cap(s) for the top of the carb(s) with a metered hole. You can tune by vacuum if that's all you've got. But a piece of hose and your ear will get you old school close. There are homemade versions of a manometer if your handy on youtube.

You can't tie the manifolds together until after you've sync'd.

Water and electric chokes are just heaters that operate a bi metallic spring that opens the flap. Unless you live in a really cold place- adjust to least amount of choke.
 
61porsche said:
The rear choke- adjust. It's rich if you look at the front. Slightly loosen the three screws and rotate clockwise 1/4" or so. Yes, adjust the flap slightly open. They should be even to each carb.

You say there's power to the electric chokes. I don't see it. It's usually a green wire and there's not a connection to either carb- the open spade.

I don't see idle solenoids either. You have early carbs.

The vacuum lines to the manifolds. there shouldn't be a Y connection. It's just a hose connecting the two. Where the Y goes I can't tell. But distributer is my guess. That requires ported from the other side of the carb not manifold pressure for early carbs.

Unfortunately, you can't use a carbmate unless you make up a cap(s) for the top of the carb(s) with a metered hole. You can tune by vacuum if that's all you've got. But a piece of hose and your ear will get you old school close. There are homemade versions of a manometer if your handy on youtube.

You can't tie the manifolds together until after you've sync'd.

Water and electric chokes are just heaters that operate a bi metallic spring that opens the flap. Unless you live in a really cold place- adjust to least amount of choke.
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Thanks but I have rectified the cold start issue, the rear choke unit was faulty and has now been replaced. The choke units have double spade connectors, the feed wires are connected to the bottom spade in the photo. The solenoid is mounted above the upper brake servo. The chokes are both functioning correctly now. The vacuum hoses are connected to a Y piece, the third branch of which is connected to a stub on the underside of the air filter housing. As this is removed in the photo this hose is just lying down below the manifold. The distributor advance hose comes from the opposite side of the front carb. Regarding the Carbmate Steve Josie shows this being used connected to the vacuum ports, not to caps on top of the carbs therefore I am trying to replicate his setup that does work for him. The vacuum hose arrangement is no doubt different as mine is a UK spec car however the setup principle for balancing the carbs should be much the same.
 
Stevehose said:
Plug the vacuum lines at the carbs and see what happens.
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Is this a different arrangement to your setup Steve ?. I don't know if mine is connected per original or if it has been modified. Certainly the connection to the underside of the air filter box looks correct but the two carb connections into the same y piece I'm not sure.
 
I don't have the 2 downdrafts any more, what I am suggesting is eliminating any chance of vacuum leaks/improper connections to solve your issue when reinstalling the air cleaner. As 61Porsche said the vacuum advance was hooked to the ported vacuum side, the retard function was hooked to the manifold side. I would eliminate both for now to get it running well. Either plug the lines from the carbs or cap them on the take-off's at the base of the carbs. Then worry about vacuum connections later.
 
Stevehose said:
I don't have the 2 downdrafts any more, what I am suggesting is eliminating any chance of vacuum leaks/improper connections to solve your issue when reinstalling the air cleaner. As 61Porsche said the vacuum advance was hooked to the ported vacuum side, the retard function was hooked to the manifold side. I would eliminate both for now to get it running well. Either plug the lines from the carbs or cap them on the take-off's at the base of the carbs. Then worry about vacuum connections later.
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I think we're getting crossed wires here. The car runs fine with everything connected as described. My issue is not being able to use the Carbmate to synchronise the carbs with the air filter housing in place as the revs drop down to 3/400. It works ok with the air filter housing removed but as the idle speed increases after refitting the housing I can't then resynch the carbs. I bought the Carbmate as I figured it was the best way to achieve this however it doesn't appear so. Ideally I'd like to make all of the adjustments with the filter housing on but I can't get to the front carb butterfly screw. Irrespective, I cant use the Carbmate with the housing on anyway as it screws up the idle speed.
 
E3_UK said:
I think we're getting crossed wires here. The car runs fine with everything connected as described. My issue is not being able to use the Carbmate to synchronise the carbs with the air filter housing in place as the revs drop down to 3/400. It works ok with the air filter housing removed but as the idle speed increases after refitting the housing I can't then resynch the carbs. I bought the Carbmate as I figured it was the best way to achieve this however it doesn't appear so. Ideally I'd like to make all of the adjustments with the filter housing on but I can't get to the front carb butterfly screw. Irrespective, I cant use the Carbmate with the housing on anyway as it screws up the idle speed.
Click to expand...

i think jerry (aka @61porsche ) told you well
when using the vaccum ports (i understand by these the two tubes that come out from the intermediate section of the carbs in the left hand side and that finally are connected to the Y piece and finally to the air filter box), you should place a cap on top of each carb to close the entrance of air except a hole of 18mm in diameter, this is the way to replicate the effect of the air filter box and to avoid such differences in iddle
 
deQuincey said:
i think jerry (aka @61porsche ) told you well
when using the vaccum ports (i understand by these the two tubes that come out from the intermediate section of the carbs in the left hand side and that finally are connected to the Y piece and finally to the air filter box), you should place a cap on top of each carb to close the entrance of air except a hole of 18mm in diameter, this is the way to replicate the effect of the air filter box and to avoid such differences in iddle
Click to expand...
I understand now, thanks. I thought he meant the Carbmate had to be connected on top of the carb.
 
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