7 replies to this topic

[dsgoody]

I have some questions with the Carb plumbing (HIF38) and the Charcoal Canister system on my 1993 British Open Classic. The previous owner had some starting issues so the garage he took it too appears to have disconnected the Charcoal Canister and the breathers from the Carb leaving the fuel overflow exposed and put a cap on the breather connection.

 

I’ve ordered up a Y piece to reconnect the breathers to the Carb rather than having them vent to air but I’m unsure how the Charcoal Canister system reconnects. I have two pipes coming out from the inner wing, one appears to return to the fuel tank and the other is just loose sitting behind the Carb. Looking at the parts diagrams I should have a thermostatic switch and I don’t see one anywhere. Would I be better off just fitting a traditional fuel overflow? Does anyone have any photos or diagrams of how the system is supposed to connect up?

 

Dave.

[RedRuby]

Have a look at the fourth picture on sprocketmans explanation of how the spi works under his pinned thread having trouble with spi's. My understanding is that there is a pipe coming from the charcoal canister through the near side wing to the purge valve bolted just in front of the wiper motor an emission pipe on a standard set up then comes off the other side of the purge valve and connects to the emissions rail running across the back of the rocker cover area. Not sure if that is still there with your carb set up. The only two pipes in that area running to the petrol tank are the flow and return, again this is on the spi set up. Hope this helps.

[dsgoody]

Looking at the diagrams available the SPi setup seems different, http://www.somerford...age=page&id=177

 

Their isn't a Purge valve and the canister has some extra stuff on it, plus the thermostatic switch.

[Ethel]

The thermostatic switch is in place of the purge valve. Afraid I don't have a piccy handy, but there are basically "ins" for collecting fumes from the tank carb & engine. The "out" to the inlet manifold is controlled by a vacuum actuated valve on the canister that's hooked up to the inlet via the temperature switch so it only draws when the engine is hot enough.

[cal844]

my 1993 carb(HiF38) car has 3 pipes going through the inner wing, 2 go direct to the carb(different bore), the short one to the tank return. 

[dsgoody]

 

There are two small vacuum pipes that you can see.
The first runs from the carb to a T piece on a thermo switch, under the thermostat housing.
and then connects to the distributor advance.

From the other side of the thermoswitch there is a small vacuum pipe that runs off to the charcoal cannister
in the left wing.
The idea is that once the thermostat opens , the thermoswitch is made and any fumes collected in the charcoal cannister
get sucked back along the small pipe and back to the manifold.
It does this to avoid overfuelling if the engine is cold.

There are two other pipes to the charcoal filter:

The first is the overflow from the float chamber (collects fumes)
and the second collects fumes from the fuel tank and brings them along in a solid pipe
(next to the fuel line under the floor) 

 

Found this info so I probably answered my own question, although if anyone has any pictures that would be very helpful.

 

I will have a look tonight but reading about it far too much of the system is missing for me to put it back to standard.

[Mighty made]

Beat me to it

 

 

On the carb, there are two inlets for fumes to the canister :

 

1. from the tank ( runs alongside the normal fuel line under the floor

2. from the overflow (float chamber vent) on the carb

 

There are two outlets from the cannister, one vents under the wing

and one connected to the breather system.

 

There is a valve that lives on the cannister that is operated by a small bore vacuum  

pipe that connects via the thermoswitch ( under the thermostat housing) and is teed into the

 small bore vacuum advance pipe betweeen the capsule on the disy and downstream of the carb.

 

The way it works normally is that fumes from the tank and the carb overflow are absorbed by the carbon.

Until the enginne is warmed up, the thermoswitch remains closed and there is no vacuum applied to the

canister.

When the thermoswitch opens (80 degrees or so)  the small vacuum pipe allows the pulge valve on the canister  to open, allowing fumes absorbed by the carbon to be drawn into the engine and burned.  

[Mighty made]

From the OP, it seems you have a large pipe missing, and maybe the small vacuum line too.

 

There should be three big pipes going to a carb cannister.

 

1 from the tank,- in place

 

1 from the carb overflow and

1 return to the breather system.

 

When it's cold one pipe will be blocked by the purge valve- that goes to the breather system

if the pipe isn't blocked (when it's cold) then it goes to the carb overflow.