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Discussion Starter #1
The engine ran when I got the car, so I was surprised when, after much work on various systems, it simply wouldn't start even with starting fluid. This morning, I was mentally reviewing what I had done and I think I know why now. There's spark, at the proper cylinder at the right time, and there's fuel in all 4 cylinders, so it must be too much fuel.

Now that I think of it, putting a set of mufflers on the header and putting gaskets on the header, replacing the broken rear fuel pump, replacing the leaky brake booster hose, and tightening down the carb mounting nuts are all going to enrich the fuel circuit. Question is, what to do now?

The OERs were sold by IAP, supposedly with the right jets. I guess I could start throwing jets at it, but that's expensive and difficult to do with the engine not currently running.

Is it safe to assume that an OER carb, which is a new version of the SK, which is a clone of the Weber DCOE, would take the same jet sizes as an actual Weber DCOE? If so, can anyone tell me what they use in a pair of Weber DCOEs with a 40mm venturi on a car with a basically stock exhaust? (Headers with stock mufflers and pipes) I'll be pulling the carbs this evening to verify venturi size and current jetting.

One final question--even if it is over-jetted (which is what I suspect) shouldn't it run on the idle circuit if I can find the right idle mixture screw adjustment and resist the temptation to mash the accelerator pedal before turning the key?
 

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I agree with Richard that it sounds like high fuel pressure. If you car is a US model then it originally had a high pressure pump for the SPICA system. Your car could have been modified one of two different ways. It could have retained the original pump with the fuel return line to the tank or it could have received a low pressure fuel pump that is designed for carburetors. In either case you need a regulator but there are more things that could be giving you grief if you have retained the original style pump.
 

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Discussion Starter #4 (Edited)
I note you said you changed the fuel pump. Now instal a fuel pressure regulator and limit pressure to 3 lbs.
Sorry--should have mentioned that. I have the "Petrol King" installed, set to what the PO claims is 3.0. I've ordered my own gauge so I can double check.

It has a Carter booster pump in the tank and a "Mr. Gasket" pump at the midway point, both rated at 3 lbs. I'm not sure if that doubles the pressure, but I'll know Wednesday when my gauge arrives.

I agree with the advice both of you are giving--I won't mess with the jets until I'm sure it's not a fuel delivery problem.
 

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Is it safe to assume that an OER carb, which is a new version of the SK, which is a clone of the Weber DCOE, would take the same jet sizes as an actual Weber DCOE?
I strongly doubt that an OER brand carburetor would be jet-compatible with Webers. But I honestly don't know; I had never even heard of OER before you started this thread. Since IAP sold you these carbs, I would suggest posting that question to them.

can anyone tell me what they use in a pair of Weber DCOEs with a 40mm venturi ...?
I don't think you mean "40mm venturi" - the carburetor size is 40mm, right? (45mm would be the other choice). The venturi is typically ~80% of the carburetor's diameter, or about 32mm.

When people ask about venturi & jet sizing, I often point them to the paper at: http://www.dvandrews.co.uk/ (click on "View Selection and tuning of Weber DCOE/SP Carbs"). While not perfect, that procedure will get you close ( a dyno + O2 sensor will bring you closer).

it simply wouldn't start even with starting fluid.
Does the engine fire at all?

- If "no" then I'm guessing you have a bigger issue. An incorrectly jetted engine should at least fire (especially if the engine ran previously with this combination of jets). If for example, you are running 140 main jets and should have 135's, it should still start - power & economy might be off, but it would certainly start and run.

- If "yes", but it just doesn't stay running, then the issue might be something like fuel pressure or a major vacuum leak. I'd put my energy into double checking fuel pressure, gasket integrity, spark and compression before worrying about air corrector sizing.
 

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Discussion Starter #8
Lots to respond to here.

Venturi size--I'm not sure how to measure it. The number cast on the carb is 45, but I know these carbs had interchangeable venturis. I didn't buy the kit and IAP doesn't stock them anymore. I'll check in and see if they have any information. The jets on these are interchangeable with Webers with the exception of the accelerator pump jets. What's being measured to get the 45 or 40 designation? The OER is just a new name for the SK, which was a Weber DCOE copy that used Weber jets.

Firing--I get a stumble every once in awhile. Starting fluid in #4 will provoke a stumble, but has no effect when sprayed in the other three. That's why I thought it had to be flooding. If there's proper hot spark and compression at the right time (all verified) then the only thing I know of that would prevent firing would be excess fuel in the cylinder.

Was running fine--I corrected some major intake leaks and added significant back-pressure. I figured that would have the same basic effect as changing the jetting. I can't think of anything else that would prevent the engine from running, since there's properly timed spark, even compression, and fuel in the cylinders.

Mr. Gasket--I'm running a 42S, rated at 2-3.5 lbs. I've installed a return line coming off a tee with a 1/16" drilling. The bowls have fuel in them.
 

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But Mad North-Northwest
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Return line? You shouldn't have a return line with Webers.

How exactly is your system set up? The petrol king regulator is single inlet/single outlet, correct? With that set to 3psi it should go pump > regulator > carbs , no return line needed.
 

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In rereading your post, you didn't tee in a return line between the pump and the regulator, did you? If you did, that's your problem.
 

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Discussion Starter #11
In rereading your post, you didn't tee in a return line between the pump and the regulator, did you? If you did, that's your problem.
The problem predates the return line, which I just put in yesterday. I get a lot of conflicting information depending on who is responding, but I was told that with these vane-style pumps it's a bad idea to deadhead them because they're constantly running and they need to move the fuel or they overheat. The pumps sound happier with the relief line.

The line goes:

In-tank pump--filter--chassis-mount pump--tee (5/16 to carbs, 1/16 to tank)--regulator--tee at carb inlet--single carb inlet.

There's fuel in the bowls and in the cylinders. I don't think it's a fuel starvation problem due to the bypass line robbing fuel from the carbs. I guess I could move the tee to after the regulator, but I was emulating someone who put it in before.
 

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but I was told that with these vane-style pumps it's a bad idea to deadhead them because they're constantly running and they need to move the fuel or they overheat.
Do not accept anymore advice from that person.
 

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No, you shouldn't have the tee at all. Before or after the regulator, you're going to lose all your pressure down the unrestricted line. That's just wrong.

If that's a low pressure carb pump it should be fine being deadheaded. Any doubts, check with the documentation. If it cant be deadheaded you should switch to something like a Facet Gold pump.
 

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Discussion Starter #14 (Edited)
I think the usefulness of a relief line is a matter of opinion, but I should make a few things clear. First, it's not "unrestricted." It's 1/16, as compared to the 5/16 through line. The 1/16 section is 3/4" long, providing what I would think would be significant restriction. Second, this car was converted from SPICA, so I have to use an in-tank pump and can't use the Facet alone. Well, I can, but I'd prefer to not have to periodically pressurize the tank with a leaf blower if I lose prime.

The problem I'm trying to solve was there before I installed the tee. There's fuel in the bowls. There's plenty of flow to the carbs. Whether or not the tee is there, the engine shows identical symptoms. I appreciate the advice, but this is an argument that's been hashed out in other threads with no resolution. I chose not to deadhead my pumps. The relief line works for some people, and it's not the cause of my current problem.
 

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Discussion Starter #15
I strongly doubt that an OER brand carburetor would be jet-compatible with Webers. But I honestly don't know; I had never even heard of OER before you started this thread. Since IAP sold you these carbs, I would suggest posting that question to them.



I don't think you mean "40mm venturi" - the carburetor size is 40mm, right? (45mm would be the other choice). The venturi is typically ~80% of the carburetor's diameter, or about 32mm.
I just heard back from IAP. They were selling these in 2006 when Weber was on strike. It's a 45mm body with 40mm chokes. They're also supposedly jetted for this particular engine.
 

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I might agree with you IF you were still running the SPICA pump. That's a high pressure / high flow pump.

If you switched to the 3-4 PSI Mr. Gasket, that's a LOW pressure pump. It's not going to work the same, even with the same return line setup.

Did it ever run properly with the Mr. Gasket pump, or is that one of the things you changed between when it worked and when it didn't?
 

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Discussion Starter #17 (Edited)
Did it ever run properly with the Mr. Gasket pump, or is that one of the things you changed between when it worked and when it didn't?
It never ran with the Mr. Gasket pump. I added that after it stopped working. Before the problem emerged, I hadn't done anything to the engine except adding mufflers and gaskets, and tightening down the carbs which had their bottom nuts finger-tight. After that point, I couldn't get anything but a stumble. New lines and pumps, in case it was a fuel volume problem--no change. Electronic ignition in case it was a spark intensity problem--no change. I started by draining the tank and re-filling it with fresh gas before I even tried to start the engine.
 

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But Mad North-Northwest
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Then that is a problem. The Mr. Gasket is a low pressure carb pump: completely different animal from the SPICA pump. If there's any return line between it and the regulator I suspect it's never going to build up enough pressure to open the 3 PSI regulator.

Not saying it's your *only* problem, but it's not good. For starters try pinching off the return line, see if that makes a difference.

So the start of this whole thing was that the original SPICA electric fuel pump died? Ideally you should have gone with another SPICA-type pump, or stayed with the LP pump and yanked the return line. The Facet Gold pump is self-priming up to 18" lift and *likely* does not need the in-tank pump with your car when used with carbs.
 

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I think the usefulness of a relief line is a matter of opinion, but I should make a few things clear. First, it's not "unrestricted." It's 1/16, as compared to the 5/16 through line. The 1/16 section is 3/4" long, providing what I would think would be significant restriction.
I agree that the return line isn't what is causing your car to not start. I've lost track of what sort of fuel pump(s) you have - some types of pumps don't like to be dead headed (if the logo on your grille looks like the one below, then deadheading is OK {yes, that was a joke}). But the T fitting + restrictor set-up you describe is probably OK - perhaps not necessary, but probably OK.

Cheburashka said:
I just heard back from IAP. They were selling these in 2006 when Weber was on strike. It's a 45mm body with 40mm chokes. They're also supposedly jetted for this particular engine.
That is a HUGE carburetor for a 1,962 cc engine. I'd suggest that you go through the venturi sizing procedure in that Dave Andrews paper that I referenced in post #5; that'll indicate a venturi of about 32mm for 1,962 cc's running at "street" rpm's. Keep in mind that the AREA of the venturi is what matters, so a 40 mm venturi is 56% larger than a 32mm (40/32^2 - 1)

How well did the engine start and run before? Would it idle at low rpm's? With such a large venturi, I'm wondering how much airspeed you are pulling through the carbs when cranking; if your gas is at all stale, it may just not be atomizing. Still, it should fire with starting fluid (you're using spray ether, right?).

Cheburashka said:
Venturi size--I'm not sure how to measure it.
Each of the four barrels in your two carburetors should have a device inserted into it that looks like the part pictured below. That's the venturi. The OD will measure 45mm if you have 45mm carburetors. The ID is the venturi size - I guess 40mm in your case.

 

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But Mad North-Northwest
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Jay, the point is the car was apparently running, then it suddenly wasn't. That's not a jetting problem, or a venturi problem, or a carb size problem.
 
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