Plugs
- Thread starter stina
- Start date
stina wrote,...
So with the engine idling, doing this makes no difference but pulling the choke out will see it rev cleanly?
Nothing to lose so I would put back the original needle valves etc then they can be ruled out.
Ron.
So with the engine idling, doing this makes no difference but pulling the choke out will see it rev cleanly?
Nothing to lose so I would put back the original needle valves etc then they can be ruled out.
Ron.
Hi Stina,
So with the line disconencted from the top of the fuel filter and the engine cranking over, you do see fuel spurting up quite significantly? If so then that will essentially rule out the fuel pump and all before as being the problem.
What level did you set the floats too?
Ron.
So with the line disconencted from the top of the fuel filter and the engine cranking over, you do see fuel spurting up quite significantly? If so then that will essentially rule out the fuel pump and all before as being the problem.
What level did you set the floats too?
Ron.
Oh Dear!!
I thought at last contact you'd got it sussed, Stina.
Seems to me that drastic steps are needed now! My next one would be to beg, borrow or steal an electric pump to nail the fuel supply question once and for all.
I'd also want to go through the other things that can draw air into the inlet manifold one more time, ie the one way valve to the servo hose, the servo hose itself, the servo (tank holed and drawing air slightly?), the take off to the distributor, the pipe to the distributor and the vacuum advance unit on the distributor.
I suppose it must be possible that the manifold to head joint has failed and you are drawing in air there too. But I really don't like that one.
Then It's set the fuel levels in the float chambers - it must be possible to get that wrong with the wrong combination of float type and needle valve type?
After that the only thing I can think of would be wear in the throttle spindles allowing air draw, and /or the butterflies not seating correctly in the throttle opening.
Have you now renewed needles and jets?
Chin Up!
Chris
I thought at last contact you'd got it sussed, Stina.
Seems to me that drastic steps are needed now! My next one would be to beg, borrow or steal an electric pump to nail the fuel supply question once and for all.
I'd also want to go through the other things that can draw air into the inlet manifold one more time, ie the one way valve to the servo hose, the servo hose itself, the servo (tank holed and drawing air slightly?), the take off to the distributor, the pipe to the distributor and the vacuum advance unit on the distributor.
I suppose it must be possible that the manifold to head joint has failed and you are drawing in air there too. But I really don't like that one.
Then It's set the fuel levels in the float chambers - it must be possible to get that wrong with the wrong combination of float type and needle valve type?
After that the only thing I can think of would be wear in the throttle spindles allowing air draw, and /or the butterflies not seating correctly in the throttle opening.
Have you now renewed needles and jets?
Chin Up!
Chris
stina
New Member
Hi guys . Don't know if i've found the problem but i've found "a" problem . I'll try to explain . I took Rons advice and took the outlet pipe off the top of the filter . Other half spun the motor over and the fuel spurted up about 18 inches , i guess ruling out any pump problems . Started it up and still running rubbish . After letting it warm up i fiddled with the mixture to get the best tick over i could find . With it running like this i screwed the left carb mix screw right in and it picked up a little , screwed it right out to the point that the screw would of been off the bi metal jet assembly and it still kept running . I then repeated the same process on the other side . Screwed the left carb in rich enough to keep it running then leaned off the right carb and it stopped . I repeated this proses enough times to make sure it was consistent . Removing the dash pots and looking at the jets the left hand wont drop as low as the right by a fair amount , i think pointing to either a bent , wrongly seated or broken bi metal jet adjuster . I have bits here to change it so i'll be doing that tomorrow pm ( ran out of time today . I know the guy with the lpg conversion had this trouble a while ago ( cant find your name at the minute , sorry ) At the weekend i changed the right carb as i had i good borrowed spare . I had a left but wasn't sure of the condition so just put my old needle valves back in the original . If this turns out to be the problem i cant understand how it ran so well the day after i did the needle valves and float levels on a 30 mile run . Also it did run o.k for a brief spell over the weekend . guess i'll know tomorrow .
Also i have totally lost my mixture settings now . Where is a good starting point . I know i've read level with the bridge then down two turns but is this the alloy bridge on the body or the top of the brass jet bearing ?
All a bit garbled i know but i've done so much in the last week !
Also i have totally lost my mixture settings now . Where is a good starting point . I know i've read level with the bridge then down two turns but is this the alloy bridge on the body or the top of the brass jet bearing ?
All a bit garbled i know but i've done so much in the last week !
Hi Stina,
The mechanical pump certainly moves a bit of fuel doesn't it... :wink:
So it looks like you have narrowed it down to one or both carburettors, and yes the initial setting is two turns down from the top of the aluminium alloy bridge. From there it is a matter of fine tuning, using the lift pins as a guide when the time comes. It is necessary that both can be identically adjusted. If this is not possible, then you have found a problem that needs rectifying.
Ron.
The mechanical pump certainly moves a bit of fuel doesn't it... :wink:
So it looks like you have narrowed it down to one or both carburettors, and yes the initial setting is two turns down from the top of the aluminium alloy bridge. From there it is a matter of fine tuning, using the lift pins as a guide when the time comes. It is necessary that both can be identically adjusted. If this is not possible, then you have found a problem that needs rectifying.
Ron.
stina
New Member
O.k guys . Now were getting somewhere . As i posted last night the jet in the left card wouldn't screw in enough to get a rich enough mixture . Removed the carb this afternoon ( again ) to check the bimetalick jet locater / adjuster . On comparing it with a spare there was no differance . I screwed the jet out to full rich with the float cover off then tried the lid , it wouldn't fit ! I removed the jet to compare with a spare and it was about 5 mill longer . Spoke to the su carb company and they say all the jets are the same size ( length ). So all i can think is the 90 degree elbow on the bottom of the jet had come adrift and slipped down thus not allowing full adjustment before it hit the float chamber cover . I fitted the spare jet ( cheers jules )and refitted the carb and it runs great again . It did faulter a little under load but i weakend the mix a little and went for a test run and it,s good . It'll need setting up but i've ordered two service kits including new jets so no point until i fit them . ( carbs off again , I can do it in about 10 mins now 
) It is drivable again and sounds lovely . I would love to know why the jet elbow dropped , and suspect Phillipe who posted under " bad fuel " a few weeks ago may of had the same problem .
I wish i,d spotted this 10 days ago , but then i wouldn't of had all this fun eh ??? :?
) It is drivable again and sounds lovely . I would love to know why the jet elbow dropped , and suspect Phillipe who posted under " bad fuel " a few weeks ago may of had the same problem . I wish i,d spotted this 10 days ago , but then i wouldn't of had all this fun eh ??? :?
Stina, I think I'm as relieved as you are to hear this news. I do suspect this may be a fairly common fault, as I've heard numbers of people with experience in HIF SU fitted classics react to a badly running engine by changing the needle and jet assembly. Perhaps, now we know why!
Well Done!
Chris
Well Done!
Chris
What a strange thing to have happen Stina.. :shock: Glad that you found it. The process of elimination will also lead to a result!!
Ron.
Ron.
stina
New Member
Hi all .
Dismantled and rebuilt carbs over last three afternoons ,with full service kits and set them up with minimal equiptment . Have her running sweet on a test run , ( About 8 miles ) , I will try to write a full idiot proof guide to what i've done .
IE : i,ve read so many times how to balance the carbs , but only just realised you need to disconect the two carbs on the connecying fork then set the fork to the correct spec in the manual there after . Will do some mies this weekend then report back , !!!! Hopfuly
Found so many little thinge wrong , the odd perished O ring in the choke system , seal in the throttle shaft etc . One choke not totally shutting off .
I,ll try to write it up in a way that may help
stina
Ps Got my tame carburetter guru booked in next Sat for fine tuning :? He knows stuff :?
Dismantled and rebuilt carbs over last three afternoons ,with full service kits and set them up with minimal equiptment . Have her running sweet on a test run , ( About 8 miles ) , I will try to write a full idiot proof guide to what i've done .
IE : i,ve read so many times how to balance the carbs , but only just realised you need to disconect the two carbs on the connecying fork then set the fork to the correct spec in the manual there after . Will do some mies this weekend then report back , !!!!
Hopfuly Found so many little thinge wrong , the odd perished O ring in the choke system , seal in the throttle shaft etc . One choke not totally shutting off .
I,ll try to write it up in a way that may help
stina
Ps Got my tame carburetter guru booked in next Sat for fine tuning :? He knows stuff :?
