Questions about '74 B210 air and fuel system

[SPECTRE]

I just bought my first Datsun. (w00t!) It's a '74 B210 and I have a couple of questions.

 

1) It will usually stall out if left idling, unless I give it gas. The last owner claims that it started doing this when he installed a larger exhaust muffler, if that's true then it seems that blocking off the exhaust pipe a bit would solve the problem because it would give it more backpressure. Is that a correct conclusion? (I had the idea of trying to set it to a higher idle RPM but someone told me that would burn out the clutch faster.)

 

2) A friend suggested another solution to the stalling-at-idle problem which is to install a dual carburetor. Would that also do the trick? It looks like they go for around $300+ on ebay.. is there a cheaper option for a dual carb from other make or model vehicles? I see KING RAT suggesting one from a sport bike in another thread but it looks like they have to be custom modified.

 

3) There is an air hose that runs from the block to the intake manifold inlet that is falling apart, it has huge holes in it. Is this an EGR system without a valve? Could this be part of the problem or would a solid hose make the problem worse? And what is this hose called exactly when looking for a replacement part? I've searched for things like "carburetor rebreather hose" and "carburetor recirculation hose" but haven't found anything similar. If I had to I could just get some high temperature rubber hose to replace it but it would be nice to know what it's called exactly.

 

[datzenmike]

1/ A less restrictive exhaust may run slightly leaner. There is an idle mixture adjustment screw for setting the idle mixture. It's located on the valve cover side in the center of the carburetor base. In is leaner and out is richer. The idle speed screw is more to the rear and only speeds up or slows down the idle. The idle speed or any engine speed has nothing to do with wearing out the clutch. Only the driver can do this.

 

2/ Dual carbs are much more complex to deal with and are not really a cure for fixing a stalling condition. You carb should be more than capable of working properly if adjusted.

 

3/ If it is from the block, it is the block vent pipe and it should connect to the PCV (positive crankcase ventilation) valve on the intake manifold. The hose could be called the PCV hose? Maybe the block vent hose?

 

The one circled is called a stove pipe and it directs exhaust manifold heated air to the air filter housing. The air filter has a temperature sensor and opens and closes a valve on the snorkel to mix cold and warm air and regulate the air temp to around 90 to 100 degrees no matter how cold it is outside. This improves engine running and performance in all weather. Most auto supply stores sell it by the foot. Or just duct tape it up.

[SPECTRE]

Thanks for the great info, datzenmike. I see now it was actually your comment in that other thread about dual carbs and KING RAT is just a title.

 

I've now tried adjusting the idle speed screw (rear) and the idle mixture screw (center). So far I've turned the idle speed screw 6 full turns counterclockwise and the idle mixture screw 3 full turns counterclockwise. It does seem to idle faster but it still stalls out the same as it did before.

 

I asked a muffler shop if they had anything to reduce the muffler hole diameter and the mechanic tried covering the muffler hole with his (gloved) hand so we could test the backpressure theory and that had no effect either.

 

I will keep adjusting the carburetor screws but since they don't seem to be having an effect on the problem, what else can I try to get it to stop stalling at idle? As you can see in the picture the fuel filter has already been bypassed with a fuel filter like a riding lawn mower would use. (This was something the last owner tried to fix the stall out problem.)

[SPECTRE]

I found another thread on it, I'll try what's suggested here and report back.

http://community.ratsun.net/topic/7222-carburetor-problem-pictures-help-wont-idle/

[SPECTRE]

I'm currently looking for a service manual for a the '74 B210. So far the closest I've found is for a '76 which is helpful but the hoses and wires that run to and from the carburetor, air cleaner, etc, are not the same. I've sent a PM to Dguy210. http://www.datsun510.com/is down until at least July, not sure if they have the manuals there. Someone told me I would find it at http://datsun1200.com but I don't see a manual for an A13 there.

 

Anyway, I have found that a hoses from the air cleaner are not connected to anything. I don't see anything for them to connect to either, except one hose behind the carb is connected in a loop which may not be correct. So I would like to find a manual to figure out the correct hose routing. There are also a couple wires that are not connected to anything. There are also 3 bolt holes around the sidewall of the air cleaner that are open and I'm guessing they should be sealed off.

 

Things I've tried so far:

1) Adjust idle and mixture screws.

2) Spray carb cleaner everywhere I can fit the little red straw; in the idle aND mixture screw holes, in the 2 bolt holes under the porthole that shows the fuel level inside the carb, in the carb inlet.

3) Replace stove pipe hose, replace deteriorating crankcase breather hoses, replace fuel line from pump to carb.

4) Inspect porthole in the carb that shows fuel level, it is a bit over half full.

5) Take a block of wood and hit it with a hammer on the carb inlet.

 

I have the idle and mixture screws so loose that I'm worries they will fall out while I'm driving.

 

Sooo.. I'm going to keep reading through the other thread on carb troubleshooting for stalling, but I think the most likely suspect currently is the misrouted/disconnected hoses and wires ,so if anyone can point me toward a '74 B210 service manual I would appreciate it.

[Dguy210]

Sorry, Spectre I only have phone no internet currently at my house so I don't see the pm's automatically unless I think to check for them. I don't think I have a spare '74 manual, and if I do it is currently 600miles away. I'm not sure I've seen a 74 pdf, I do have a 74' manual with me and can take pics of certain pages (at Canby now) later. Also, you are correct, the 74 is actually very different on the wiring and hoses (74 lacks the engine bay relay box thing). What did you need exactly?

[SPECTRE]

Sorry, Spectre I only have phone no internet currently at my house so I don't see the pm's automatically unless I think to check for them. I don't think I have a spare '74 manual, and if I do it is currently 600miles away. I'm not sure I've seen a 74 pdf, I do have a 74' manual with me and can take pics of certain pages (at Canby now) later. Also, you are correct, the 74 is actually very different on the wiring and hoses (74 lacks the engine bay relay box thing). What did you need exactly?

 

Hey Dguy210! Just the guy I was hoping to see. If you could take pictures of any of the following I would greatly appreciate it:

 

1) Diagrams of components and routing for emissions/fuel system(where it connects to the carb)/air cleaner/carb itself

2) Tune up procedures for those systems

3) Electrical diagrams and routing for those systems that regulate air and fuel valves/solenoids around the carb.

 

Sorry to bother you while you're busy, no rush, and thank you.

[Sierra]

Here are some diagrams, I found helpful when I was trying to figure out the emission system of my 78.

 

 

 

 

 

[Dguy210]

https://drive.google.com/file/d/0B8T_OnFOG-hVb05McW1iVmp4dFU/view

 

'74 Service bulletin, some useful stuff but not the service manual. Should have a wiring diagram at the end though. Looks like the only scanned manual I know of is for a '75 and I don't have access to a copy right now (on other computer at the old house). Haven't had a chance to take any pics of my '74 manual yet, unfortunately.

[SPECTRE]

https://drive.google.com/file/d/0B8T_OnFOG-hVb05McW1iVmp4dFU/view

 

'74 Service bulletin, some useful stuff but not the service manual. Should have a wiring diagram at the end though. Looks like the only scanned manual I know of is for a '75 and I don't have access to a copy right now (on other computer at the old house). Haven't had a chance to take any pics of my '74 manual yet, unfortunately.

No worries! Thanks Dguy210. I have the engine pulled on my Subaru right now so I haven't had time to dig into the Datsun's carb yet anyway.