Carbs
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Harlequin
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do you have a fuel regulator fitted ?
Harlequin
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Should have a regulator...your 34's like to run at 2.5-3psi ...your stock pump can push out 7-8psi
Harlequin
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mattd1984 said:
Holley with gauge in-line
Harlequin
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got a pic of it in my engine bay...
Not really Matt, the cylinder heads will be hot enough for combustion for a couple of minutes after the ignition is turned off as long as there's a fuel feed.
It's called "dieseling", that's why there's fuel cut-off valves on standard carbs.
It's called "dieseling", that's why there's fuel cut-off valves on standard carbs.
fire3500
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Could also be a result of excessive carbon in the combustion chambers, possibly due to running rich. Used to affect cars running on Four Star in "the olden days"... how are the plugs looking? Used to have to "decoke" old BL clunkers from time to time as a result of that...
Mentioning this as I'm not entirely sure, but fairly confident, that Weber ICT's don't have a fuel cut-off valve and so unless you're meeting that somewhere else in the fuel system (e.g. within fuel pump / regulator or dedicated valve) you might not have that, and with even modest carbon deposits building up and remaining hot enough to ignite the fuel even once ignition is shut off dieseling might be caused.
Pull a plug and have a look... if it's blackened / sooty then I'd give this theory at least a little credence, if it's tan or grey then ignore me (but deal with the grey as that'd be a lean engine).
Mentioning this as I'm not entirely sure, but fairly confident, that Weber ICT's don't have a fuel cut-off valve and so unless you're meeting that somewhere else in the fuel system (e.g. within fuel pump / regulator or dedicated valve) you might not have that, and with even modest carbon deposits building up and remaining hot enough to ignite the fuel even once ignition is shut off dieseling might be caused.
Pull a plug and have a look... if it's blackened / sooty then I'd give this theory at least a little credence, if it's tan or grey then ignore me (but deal with the grey as that'd be a lean engine).
That's why I've got a fuel cut off solenoid fitted under the tank with an fused ignition feed.
Not if the engine's still turning, it's driven off the distributor drive shaft.
Trikky2
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mattd1984 said:Yer that was a pretty dim question thinking about it now!
A regulator and cut off wont cure the problem because even if you cut off the fuel to the carb it will still run on from the fuel in the float chamber.
Thats why stock carbs had a cut off valve that shut fuel off to the jet - not to the float chamber.
With modern fuel its unusual to get running on however.
As already posted, either you have a lot of carbon build up or your engine is overheating a bit.
Have a look at the plugs to check for carbon. It can build up from over rich running or from burning oil.
The excess carbon should normally burn off if you give it some welly but if it keeps coming back after a bit then you need to investigate further.
Plugs seem fairly black and sooty. It has been setup to run quote rich. Black mark on the bumper etc.
This was how the guy who set the carbs on the rolling road set it up.
How can I go about removing the carbon build-up?
This was how the guy who set the carbs on the rolling road set it up.
How can I go about removing the carbon build-up?
fire3500
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Well, if you get the mixture right then it should decrease the issue but it's better that it was running rich than lean
As for removing carbon build-up the only way to see it and to clean it off by hand would be to pull the heads. However, there are treatments available that claim to chemically do this... my experience has been variable (and importantly I've not had this problem with aircooled VWs but with Minis). Your motor is still quite new though and is a Morena engine? You did quite a bit of touring with it and so I'd seek the input of the engine builder... not in a "WTF" kind of way, but more to get the benefit of their experience and perhaps knowing what you were looking for and building for reliability could be why it's erring on the rich side.
I'd hate to give you "definitive" advise that damaged your engine, and without seeing it'd be a real "guess" rather than anything substantive. So either get the spanners out or / and talk to your engine guy
As for removing carbon build-up the only way to see it and to clean it off by hand would be to pull the heads. However, there are treatments available that claim to chemically do this... my experience has been variable (and importantly I've not had this problem with aircooled VWs but with Minis). Your motor is still quite new though and is a Morena engine? You did quite a bit of touring with it and so I'd seek the input of the engine builder... not in a "WTF" kind of way, but more to get the benefit of their experience and perhaps knowing what you were looking for and building for reliability could be why it's erring on the rich side.
I'd hate to give you "definitive" advise that damaged your engine, and without seeing it'd be a real "guess" rather than anything substantive. So either get the spanners out or / and talk to your engine guy
