spunkymonkey
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Post by spunkymonkey on Jun 10, 2008 10:16:17 GMT
The carb on our 33 has what appears to be a solenoid valve which is energised direct from the ignition coil. It's not shown or mentioned in the Autodata book so does anyone know what it is? I'm guessing that it's an anti-run-on valve to shut fuel to the jets when the ignition's off & have plans for it if it is but don't want to mess about with existing wiring unless I'm sure and don't want to strip the carb just to find out. Anyone know for sure
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Post by dafdaffer on Jun 10, 2008 12:52:53 GMT
HI, as you guessed it is an anti run on valve, ask Richard B he is an expert on this Valve ;D
a few weeks ago i went to rutland and my car started missfiring and cutting out, i checked the points and most other things but couldnt see what was wrong, richard told to check the wire to the valve and it had fallen off.
the valve is powed ffrom the ignition circuit so when you turn off the key the valve shuts off.
most 33's that i have seen and 44's have the valve.
Paul
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spunkymonkey
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Post by spunkymonkey on Jun 10, 2008 14:45:13 GMT
Thanks Paul. I'll try to remember a photo for you later today, John - may be some UK special fit The plan, btw, is to look at an over-run fuel shut-off. No throttle (will need a switch) + engine speed high enough (needs speed sensor) to guarantee a restart (around 1200 revs) = shut off the fuel. As soo ans throttle is opened or engine speed drops = supply fuel again. Effectively infinite mpg any time you're coasting which adds up to quite a lot overall. Vacuum should still be available cos the engine is still sucking but pure air rather than air / fuel. A lot of modern cars with injection use it & can't see any reason why it wouldn't work with a cut-off in the idle ciruit on a carb. If anyone can think of any big reasons why not can you say now before I start designing speed sensors etc?
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Post by Richard DAF Webmeister on Jun 10, 2008 16:24:57 GMT
HI, as you guessed it is an anti run on valve, ask Richard B he is an expert on this Valve ;D Ha!! Well yes, I have had some experience with these strange little valves. The Blue Bullet's had a tendency to work loose from the carb, due to the vibration of the engine, therefore losing the electrical connection. The result was that the engine would "run rough" and cut out at junctions/traffic light stops etc. Then I also discovered that the thin cable that connects it to the thingies, was breaking up inside, again causing hit and miss electrical connection. A new cable, clip and a firm tighenting of the valve into the carb, seems to have sorted that little issue out - so far! I believe that Chairman Alex may have taken a pic of me "advising" Paul at Rutland... Fortunately we have yet to see the evidence!
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daf44
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Post by daf44 on Jun 10, 2008 21:11:18 GMT
hi joe.
speed sensors are easy. most rev counters run straight from the points anyway. As long as the valve opens and closes fast enough you should not have a problem. you may need a different solenoid to achieve this as the original may not cycle fast enough but i cannot see this causing you any major problems.
good luck
paul44
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spunkymonkey
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Post by spunkymonkey on Jun 10, 2008 21:58:58 GMT
Cheers, Paul. Not sure it'll make a whole lot of difference but with prices as they are, every drop helps! And there is something nice about heading down hill in the Colt with the trip computer saying "99 mpg" John, here's a pic for you in case you ever come across one over there...
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spunkymonkey
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Post by spunkymonkey on Jun 11, 2008 8:34:36 GMT
It's not for sped, John. It's a solenoid valve that shuts off the idle circuit inside the carb when the ignition is off so fuel stops flowing as soon as you turn the key off to prevent any chance of dieselling / running on.
My plan is to fit a speed sensor and a throttle position switch so that it will also shut the fuel off when you have no throttle and the engine is turning at more than about 1200 rpm - which should only happen when you're slowing down. As soon as you move the trottle, or the speed gets low enough, it will allow fuel again and bump-start itself - hopefully without you even noticing!
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Post by veeruk on Jun 11, 2008 10:04:41 GMT
Good idea to save fuel. However, if the engine goes down to zero revs (stops running) then your clutch shoes will retract. This means that it disengages the engine from the rolling parts i.e. the variomatic. It will not bump start as the clutch shoes only engage again when the engine revs above a certain speed. You'd have to start it with the key. Well, that is my theory.
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spunkymonkey
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Post by spunkymonkey on Jun 11, 2008 11:13:31 GMT
Except that the engine will still be spinning. On over-run the wheels are turning the engine rather than the other way round. The clutch doesn't care what's making it spin just as long as it's spinning. As long as the (wheel driven) engine speed stays above 1000 revs or so there's still a connection - that's how you get engine braking!
It'll be sparking all the time so, as long as fuel starts flowing again before the revs drop low enough for the clutch to disengage (around 900 rpm???), it should simply carry on burning where it left off.
Certainly, on the Colt, there isn't even the slightest hint that it's doing it - but that is with injectors that can cut the fuel at the point of delivery rather than upstream in the manifold.
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Bob Scrivens
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Post by Bob Scrivens on Jun 11, 2008 22:15:34 GMT
Hi Joe well it sounds good to me, might have to make the unit adjustable initially, to allow you to experiment with the cutting in speed. Could also be a saving on the brakes on a down hill run and improved engine cooling? Will be interested to see how you get on with the project.
Bob.
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spunkymonkey
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Post by spunkymonkey on Jun 12, 2008 10:19:24 GMT
Will do. Probably need to get the MOT etc sorted first though - it's a little hard to get above walking pace off-road where it is which isn't really enough for any over-run on flat ground - but I'll update when I get a chance to experiment.
At the prices we're reacing now any extra helps (just saw £1.32 / litre for diesel. That's $9 for one of your gallons, John!!!)
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Post by starider on Jun 12, 2008 22:44:56 GMT
Hi,this electo magnetic jet is very important to ensure the engine idles properly.In the early 70,s there were moves to reduce emmissions from these engines, silencers were fitted with a 3/8" diameter pipe so that dealers could remove a rubber cap on the end and connect to a exhaust gas annalyser,and as someone has said, this jet/valve was fitted to prevent fuel draining from the carb.when not running.At the same time the ignition timing was altered also as part of an attempt to reduce emmissions.This valve is not unique to DAF's,many manufacturers who used Solex carbs used these. You can check if the valve is working by turning on the ignition and pulling the connector of the terminal,when you re-connect you should hear quite a loud click.It is quite common for the connector to vibrate off,and as said previously the engine will then cut out at tick-over and not tick-over at all. starider.
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spunkymonkey
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Post by spunkymonkey on Jun 13, 2008 19:19:22 GMT
I'd love to look at developing a full management system, Mac, but Sian wants her Daf as original as possible - and certainly able to be switched back to "vanilla" at the roadside. For the sake of less than a tenner in components (at a guestimate) I reckon this is worth trying.
Having just commented about £1.32 a litre a couple of days ago, had to top up at £1.35 today. Something that can save it's own cost in a matter of a gallon or so of fuel has to be worthwhile!
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