Needle valve base height

[edd]

My carbs have never performed and am now hoping to resolve a long standing problem. The engine revs lovely but on blipping it fads away and cuts out. I'm sure it has no air leaks.
I have enriched to the max with needles maxed out. Has anyone got the measurment of the female end of the needle.
It's very frustrating having lots of friends but all miles away so I might as well be in Australia.
looks like I have to cancel my Mot next week now.
Edd

[LAMBRETTLAD]

Sounds far too rich . If i pull my choke out with engine running = instant cut out .
From memory if you screw in to max ,then count the flats till minimum and start at half way to give a good starting point

[staginhiding]

Just to get everyone on the right track.
Edd needs the measurement of the jet below the surface face..

[dasadrew]

The Haynes Stromberg manual says to assemble, the top of the jet should be flush with the bridge in the carburettor bore. Thereafter, remove the damper and hold the air valve down. Then screw the jet in until it contacts with the undersurface of the air valve. Then screw out the jet adjusting screw 3 turns to set an approximate height.

All of the above only quotes from Haynes. Surely Alan (157,7) is the man for this question?

Drew

[edd]

The Haynes Stromberg manual says the top of the jet should be flush with the bridge in the carburettor bore.

That's interesting as mine is at least 2mm down
Gulp

[dasadrew]

That's interesting as mine is at least 2mm down
Gulp

Accidentally pressed the post button before I was finished! see above!

[milothedog]

That's interesting as mine is at least 2mm down
Gulp

They should not be flush Edd, 0.100" as I seem to remember. so 2mm is not far off. 1mm = 0.040" roughly. but there is a question as to where you measure that from. top of the jet body or in the middle where the jet hole is? Like I said on the phone screw in fully the trim screws by the temp compensators and set the mixture via the needle adjustment for now.

Ian.

[staginhiding]

That's interesting as mine is at least 2mm down
Gulp

Changed my mind on commenting..

[milothedog]

The Haynes Stromberg manual says to assemble, the top of the jet should be flush with the bridge in the carburettor bore. Thereafter, remove the damper and hold the air valve down. Then screw the jet in until it contacts with the undersurface of the air valve. Then screw out the jet adjusting screw 3 turns to set an approximate height.

All of the above only quotes from Haynes. Surely Alan (157,7) is the man for this question?

Drew

That reads how to set the older type with fixed needle, ours are the other way round the jet is fixed and the needle adjusted.

[Seaking]

Edd
a zenith stromberg manual is on e bay about 3 hours to go
I have the same book that I am willing to lend to you pm me your address and I will post if you wish

cheers Glenn

[Seaking]

Manual reads fixed jet adjustable needle
the jet assembly is pressed into the body and is not adjustable or removable. The needle assembly hight is adjustable through a limited range by an adjustable screw fitted in a special air valve guide rod. A key way and peg arrangement replaces the conventional needle locking screw and permits vertical movement of the needle assembly whilst preventing its rotation in the socket, thus maintaining the correct angular relationship with the jet.

Cheers Glenn

[dasadrew]

That reads how to set the older type with fixed needle, ours are the other way round the jet is fixed and the needle adjusted.

Yes. I thought Edd might have that type as he was asking about the jet position. My Stag had adjustable jets although I'm suspect that they were robbed off a TR6 by a PO. Or did some Stags have the adjustable jets by chance? This sheet out of an original Stromberg manual interestingly shows the Stag with adjustable jets.

Stromberg Parts Manual pic.jpg

[milothedog]

I suspect that the early Mk1's were like that but am not sure? maybe someone can confirm. I do know for sure that the re conditioners don't take them as exchange so it would make sense that, that is the case.

[edd]

A bit happier today . I went back to basics and checked for air leaks around the peddistool with wd40 so thanks to Sam for that tip .I decided too drop my needle valve base a few more thou to enable a richer mixture . Ian ran me through on the phone the balancing set up which I thought I was doing correctly until he mentioned re fitting the linkage. I had already adjusted the linkage a while ago and expected this not to have changed much to but my surprise connecting it turned the left hand carb a little I think this made a good difference. My mixture is set to max still and I,m finally ticking over but if I weaken by half a turn the same problem exists and the car dies on returning to idle . Until I get a co meter on the car I will have to see if I can further increase the mixture but for now it means I can at least test drive the car .
Many thanks to all that posted and tried to help even if not directly helping brainstorming is by far the best way rather be in a cold garage on your tod thinking am I ever going to get to drive this car .
Edd

I have just found this link that explains my problem , I,m glad Alan157.7 mentions to drop the base down to 3 mm as I was worried about it .

http://socforum.com/forum/showthread...t=running+weak

[flying farmer]

I had a serious misfire, backfire and spluttering fit in the Stag engine estate a few weeks ago, dropped on to 4 cylinders when booted. I stripped the float chambers expecting a serious float or blockage problem, everything checked out OK but they have only done a few thousand miles since a needles and jet rebuild.

I never removed the temperature compensators when I rebuilt the carbs ( the coffin shaped bits on the side), so I thought I would have a look at those. On the RH carb (the source of the problem), the rubber seal under the end was split, and the LH one was not far off splitting. Lacking the correct rubbers, I substituted a couple of appropriate sized O rings and reassembled.

Could not believe the difference, it starts better when cold and pulls a lot better at full throttle. Wether this was the problem I cannot be sure, or if I had disturbed something else, but it goes better now than it ever has.

When I first fitted the jets I had to knock them down a bit further to get the mixture within an adjustable range.

Neil