Stromberg Needles

[thebrookster]

Sorry guys, I simply have too much thinking time on my hands just now, so plenty of questions rolling in!

In Dave's "Ideas" thread I gave a brief description of one issue I have with my Mk1, namely I have had to set the jet a ridiculous number of turns down in order to get proper running. This has caused comment that I have the wrong needles fitted, with which I agree!

Richard has suggested that I try the Mk2 GT6 needles. So I have done some research and tried to find out the needle profiles for the two needles in question, namely the 6J I have fitted and and the 6AC from the GT6.

Now, have I got the right diameters? Cause it would appear that the Mk2 needle (6AC) is leaner than the 6J!

So can anyone please explain? Have I got the right profile dimensions? I have ordered the needle book from Burien, but this is bugging me know lol.

Cheers

Phil

[dazzer]

I think there is something fundamentally wrong Phil if you are on reasonable standard needles and you're having to take it a full seven turns down!

Firstly are you on 150 CDs and are they the early type you adjust from below. One turn down anticlockwise (from below) being 360 degrees, not one flat?

If its yes to all of the above then I'd check the needles and jets are correct and matched (will have a small 6j imprinted on the needle shoulder that locates in the piston. Then check you are starting with the needle shoulder flush with the piston and the jet absolutely level with the bridge, not protruding above.

Take it a full three x 360 degree turns down on both carbs. See if it will run OK. If not and precluding any huge air leaks I'd be inclined to purchase new needles & jets as there are different sizes of jets in strombergs between 150s and 175s. So you might have correct needles but incorrect jets or some mismatch.

Hope this helps

[thebrookster]

I can't actually recall how many turns down my jets ended up, but I can recall being slightly concerned about having the adjuster fall out!

Back to the start - yes I have 150's fitted, and yes they are the type that adjust from underneath.

Going by your thoughts Dazzer, which were heading the same as mine I wonder if I have the right bits fitted. If the jets are the wrong size that could explain it. I got the rebuild kits from Chic Doig, but I already had issues with them as I found that I had two differing float chambers fitted, which meant gaskets were not quite right. In the end I cannablised the carb from my Herald (same type) and gaskets from a set of mk2 carbs from shed1969 and got it running after a fashion (ie enough to pass the mot!).

When I get home I shall look into ordering some new gaskets, new needles and jets (the needles fitted are the originals) and also some new floats. I am starting to wonder if I have buggered up the float height somehow, as logic tells me this would also affect fueling!

I need some spares anyway to replace the bits I stole from the mk2 set, which I have semi promised to someone already! Think I might give Burlen a holler, they appear to know what they doing with stommies from appearances, and have a good rep online.

I shall also continue playing with a rather funky spreadsheet I found that compares stromberg needles, albeit minus a massive number of types. Be nice to have something that works similar to the mintylamb su needle tool!

Phil

[DJB_Harvey]

Also be aware that different weight diaphragm retaining rings were used ... Some light , some heavy ... Theses were originally matched to the needles / cam Etc

[thebrookster]

Blimey! They don't make things easy do they?

I do suspect it may well be the kit I got from Chic that was suspect, though probably unwittingly. Looming back through my old threads on the subject I have noted that the kits I bought were CDSK11, for a 150CDS carb, and according to Burlen's site the carbs I have (albeit one is an odd number they are the same physically) I wanted a CDSK1 kit for a straight 150CD carb. Might explain a few things I guess?

I see no reason why I should not be able to get back to normal running, these carbs were working fine for radders when he had the car, and worked fine for me since until I started meddling!

Another point I found when searching the old threads is I am at 6 turns down on the jet (initial 3 turns plus 3), so something is not quite right.

Phil

[thescrapman]

The set you got from Andy should have been fairly close without any adjustments.

Yes they were Mk2 carbs, but they were running well.

They might have been a bit "off" higher up the revs, but should have been fine at lower revs.

[thebrookster]

No arguments there Colin! The only reason I didn't use them in the end was because I would have to have converted over to cable throttle (mine is still rod) and I did not have the time or the parts to do so at the time.

I could still go this route, but one the original carbs worked before so no reason to not work now, and two I am not going to be beaten by set of ruddy carbs! I've got this far so I'll darn well finish 😎

Phil

[GTRoger]

I found this Stromberg needle chart, maybe it's of any use to you.

http://www.lotuselan.net/w/images/1/10/Stromberg_needle.xls

[thebrookster]

Roger - it is indeed!

In actual fact I found this the other day, and have no updated it with all the needle profiles I could find, courtesy of Vitesse Steve's very useful site of manuals which included a stromberg manual!

I have also ordered the Burien book, so will update with any additional needles found there. I will then (or now,if anyone needs it) make said file available as a counterpart to James' Mintylamb SU needle tool. If i get the time and the tools I may attempt to convert it into Java so it can be run as a mini program.

Cheers, and Merry Christmas

Phil