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Twin Webber Trouble


Guest Top Cat

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Guest Top Cat

Hi all

 

After doing a bit of porting to a std head and fitting a piper 285 cam to my 2.0 lte pinto I fired it up and went for a run to see the power gains I had managed to get. After i while lost some power and seemed to running on only 3 or even 2 cylinders, next thing I have fuel pouring out the trumpets on the front carb (twin 40 dcoe) this is feeding the cylinders that arent firing.

I checked the plugs and am getting a good spark.

Even after I turn the engine off I am still getting fuel pouring out. I am thinking this could be the floats sticking but would this afect the engine firing??

When the engine is running on two, the front carb is still sucking but fuel is pouring out.

Has anyone had this before?

 

Thanks

Trev

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Sounds like the float valve is stuck open , just give the carb a tap as that may release it, then if in doubt replace them with new ones but note the size marking on the valve.

 

The above is assuming that you have the correct fuel pressure at the carb approx 2-2.5 psi. and not too high a pressure.

 

Mike

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Guest Top Cat
Sounds like the float valve is stuck open , just give the carb a tap as that may release it, then if in doubt replace them with new ones but note the size marking on the valve.

 

The above is assuming that you have the correct fuel pressure at the carb approx 2-2.5 psi. and not too high a pressure.

 

Mike

Thanks for reply Mike, I dont know what pressure I have. I am just running a standard pinto mechanical pump which gives me enough to get the rev counter round to 6500 rpm under load

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Guest Top Cat

Ok Ive just been and checked the float valve, doesnt appear to be sticking

however the engine is not running on pots 1 and 2 and that carb is not sucking like the other one.

When I put my hand over one of the trumpets it then starts leaking fuel out of it

 

What the hell is going on here????????

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Have you checked to see if the butterfly valves are opening when you push the throttle and that the coupling linkage between both carbs is ok, if your engine has been flooded you may have to dry the plugs out,

 

Seeing you have changed the cam, i trust all is ok in that department, cam lobes lubed up and run in as per recommended,(if it is a new cam) spray bar doing what it should, etc etc

 

Mike

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Guest Ian & Carole

Are the carb balanced?

 

1st thing is make sure that they are....

 

I agree with Mike you have a needle valve problem.

 

Did you have the 40's on the previous engine? if so where they OK then???

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Guest Top Cat
Have you checked to see if the butterfly valves are opening when you push the throttle and that the coupling linkage between both carbs is ok, if your engine has been flooded you may have to dry the plugs out,

 

Seeing you have changed the cam, i trust all is ok in that department, cam lobes lubed up and run in as per recommended,(if it is a new cam) spray bar doing what it should, etc etc

 

Mike

Yes Mike the linkage is ok and the nut at the end of the butterfly shaft turns when the thottle is pushed so that part of things is ok.

 

I suppose I will have to remove the rocker box cover and make sure the cam is opening the valves properly but there are no nasty noises coming from there so dont think that will be the problem.

 

When I take out a plug it is dry!

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Guest Top Cat

Hi Ian

 

Yes the carbs were on this head prior to the new cam being fitted.

 

I didnt have them proffesionally tuned though, I intend taking the car to dave bogg in north yorkshire for tuning but need to get it running on all 4 first

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Did you check to see if the float was floating as they can puncture with age, as i have had this a couple of times in the past, plus not sucked anything like a mouse in the bellmouths i hope. Piper foam air filters have been known to fall apart and cause a blockage thats why i threw mine away and made my own bellmouth filters.

 

Check the carbs out well first and that you can see all the butterflies are opening together, before ripping the engine apart, seeing as it was running ok to start with.

 

Mike

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Guest Top Cat

Just checked that the cam is opening and closing all the valves, all is ok. the clearances I set are .010" exhaust .008" inlet.

Still not running on pots 1 and 2. carbs seem to be operating fine and a good spark. Helpppp!!!!

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Guest mower man

Hi not trying to upset you but had similar problem with apinto awhile back the head gasket had blown between 1and 2 plugs were dry but now power !,do acomp test with all plugs out I think you may find low comp on 1+2 HTH mowerman

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Guest Top Cat
Hi not trying to upset you but had similar problem with apinto awhile back the head gasket had blown between 1and 2 plugs were dry but now power !,do acomp test with all plugs out I think you may find low comp on 1+2 HTH mowerman

 

Thanks mower man, I was trying not to think down that route but you could be right, would that not show traces of water in the oil and some sump pressure as well?

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