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MG TD TF 1500 - To tickel or not to tickel
|Quote - "it should have read, "Wouldn’t it flood out the engine as the fuel will flow first to the intake manifold?" regards, Tom”|
Point taken Tom,
But there is a needle inside the main jet that restricts the flow of fuel to the engine somewhat normally . While the overflow path is possibly 4 time as big.
With the pump supplying unrestricted fuel under pressure to the float chamber [needle stuck/jammed whatever] I would put good money on petrol coming out the overflow before the engine splutters and dies.
If you have ticklers as well fuel will dispense onto the hot manifold.
Not guaranteed to burst into flame but a hazard either way you look at it.
If the only places Petrol can exit the float chamber is via the correct path to the engine or through the vent on top of the float chamber, you will be in a better place.
Why else would SU "not" drill out the tickler on new float chambers tops, but still give you the option of an overflow?
I have only ever had one incident with fuel on the manifold. - This ruddy petrol over here with 10% ethanol destroyed the rubber inside the armored hoses going to the carbs. It was spraying out in several places like a shower. My only indication was the strong smell that made me stop and look. Fortunately nothing caught fire - but if put the wind up me for a while.
blocking up the ticklers and routing the overflows to the front plate per Dave Braun's set up - just makes me feel a little easier.
|R. D. Jones|
|>Why else would SU "not" drill out the tickler on new float chambers tops, but still give you the option of an overflow?|
|As I was walking around the park I had this thought. |
If the float valve sticks, yes the fuel bowl will start to fill up and then the fuel will run out of the jet and flood the engine. But then the engine will stall. The key is still on and the SU pump is still running. The fuel bowel will then, eventually fill to the top and the fuel will run out the "Tickler" hole first. Where it will drip over the HOT exhaust manifold and could ignite.
Perhaps it is best to plug as has been suggested.
|Plugging them is safer. Not everything that was done way back then is better. Try explaining why MG chose to place leaky Zenith carbs 6 inches above cherry-red hot catalytic converters in late model MGBs?|
|Ira Spector (PA)|
|I don't know for sure, but my TF was in an accident many years ago where the right front was severely damaged, fender, broken control arm, right door and smaller bits. Due to the fact that the bonnet, especially on the right side and right side panel were warped from heat, I believe the accident was caused by an overflowing carb, causing a fire which in turn probably caused the accident during a panic situation.The rear carb bowl top, probably the culprit, was changed at the time with one without a tickler. The front carb has the tickler blocked off by the manufacture. Maybe these things were needed on very early cars with a gravity fuel feed, but there is no reason for them with a pressure system. I would not have a carburetor with working ticklers on it. If needed for show, I'd block them off so there's no possibility of fuel leakage. JMHO. PJ|
|I'm sure there was a reason they were there, since it would cost $ for parts and labor. My guess is sticky needle valves due to grit/poor quality fuel back in the day. Years ago before putting an in-line filter in (before cleaning the tank at restoration), I used them several times over the years to bump the float and free up a stuck open needle valve. They also work if it is really cold and your choke mechanism is frozen or broken- just hold the pin down for a second or two and that will flow some gas and richen things up. So I wouldn't call this a design flaw. Some replacement pins some years ago had a soft fiber-type washer under the circlip that would more or less seal the opening with the spring pressure. Mine are now for show only, JB Welded and sealed. George|
|George is absolutely right, the tickler was there to enable the owner to flush out any debris that was holding the needle valve open, due to dirty fuel (surly there are those in our group that remember when all gas pumps at stations had the word 'FILTERED' on the pumps). In a book that I have, The American Gas Station talks about the really dirty fuel that was once the norm at all gas stations and the need for filters on the pumps that served the public. |
All of the tickler pin sets (which are also used in the SU carburetors for later cars, starting with the TFs to lift the piston when checking the setting of the carburetor) now come with a rubberized washer that will seal around the hole in the float bowl lid for the tickler pin. I have not tried it, but I think that combining that washer with a hole made tighter with a layer JB Weld around the pin would make it such that very little fuel (if any) could escape around the pin in situations where the needle valve didn't shut off the flow. Cheers - Dave
|I have retained the tickler pins for the reasons stated above and two others: |
1/ They can be used to "feel" that the floats are in the right place, i.e. that there is petrol in the float chamber and the floats are indeed floating.
2/ To test that the the fuel pump is working.
This thread was discussed between 18/07/2013 and 19/07/2013
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