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Stromberg Questions

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arbs_53

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I'm thinking about putting Strombergs back on the TR250 and placing these Webers on e-Bay but I have some questions that need answers before I decide which way to go.

I still have the original carbs. They are the early type, apparently set at the factory and lack the adjustments later Z-S's had. Can these be converted over to the adjustable needle without much expense and hassle? Would two carbs be enough to feed the engine I've got (GP-2 cam, 9.5:1 compression, headers, etc.) at least until I can replenish the funds in my Triumph cookie jar. The triple set-up is the way I want to go eventually.
 
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...They are the early type, apparently set at the factory and lack the adjustments later Z-S's had. Can these be converted over to the adjustable needle without much expense and hassle?...

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My only experience is with what you call the early carbs. I was under the impression that the adjustment was added to accomodate emmission requirements. The fixed needle set-up is oh so easy to get the mixture set that I would make sure there was some advantage to the later version before doing the switch.
 
Ok, I have to plead ignorance here. I thought these carbs had fixed jets and fixed needles. How does one adjust the air/fuel mixture?
 
Sorry, I was confused. I was thinking of the early-early ZS carbs which have an adjustable jet. Later ZS carbs had an adjustable needle.

I guess you're saying there was carb in between on which neither the jet nor the needle was adjustable.
 
That's what I understand, Geo. I was just searching the web for info on this and found a couple of articles that mentioned that the jets were not meant to be adjustable, but can be adjusted if the brass nut on the bottom is removed. I tried this years ago in order to move the jet but it is either a pressed fit or the threads were really stuck, I'm not sure which.
 
Dave: I also have a TR250 with these early emissions carbs. The jet assembly appears similar to the adjustable jet assembly used on the TR-4A, which has an easy to grasp knurled knob. The jet is spring loaded like the earlier carb, which would lead one to think that it can be adjusted, but the end of the hex nut is sealed with a plug so you can't get to the jet. The needle is fixed to the air piston and can not be adjusted from the top like the later ZS carbs. I emailed Joe Curto and he does not have replacement jets for these on hand but might make a batch if there were enough orders.
I prefer the ajustable jet as used on the earlier carb and I will explore either installing the TR-4A carbs or having the TR250 jet assembly modified to use the knurled knob. I bought a set of the TR-4A carbs on ebay to experiment. I tried to install the jet assembly in the TR250 carbs but its not that simple. The end of the jet assembly that goes into the bridge of the venturi is a different diameter, but it could be modified.
 
Andy, I have contacted a guy who rebuilds and micro-polishes Strombergs and sells them as a triple set on e-Bay. After seeing his name favorably mentioned on another forum for 6-pack Triumphs, I contacted him first by e-mail and then last night by phone. He tells me with these TR250 carbs he removes the needle and drills out the hole deeper to allow up to .020 of movement to the needle, which he says is the same amount the needle adjustable carbs get. They have to be adjusted maually, you can't use the adjusting tool, but he says it isn't a problem if ones takes care to measure the amount of exposed needle accurately when synchronizing a double or triple set-up. I also asked him about the feasability of replacing the fixed jet with an adjustable one instead and he says that he's found that the jets on the TR250 carbs usually gets damaged from being pressed out with a 5-ton press and the hole sometimes eggs. When he does replace jets, he keeps the jets in the freezer for a day and then warms up the float chamber in an oven before joining the two together.
I've decided to send him my two original carbs for him to go through and he is going to supply a matching third carb, all for $625. This morning I ordered the manifold and fuel line kit from Richard Good. I'm hoping this cures my present problems once and for all.
 
Dave,
Another option for the rebuild on your ZS carbs is Gary Martin out in South Dakota. You can Google him and find his listing in Hemmings. He rebuilt my trips and brought them up to new condition for a very reasonable fee (how much, I've forgotten. I forgot what I had for lunch yesterday, too.) Then there is always Joe Curto in NY.

Bill
 
As an addendum to the previous post, Dave, I had tried the cold air induction box that Richard Good makes for the trip Strombergs on the TR6 and just didn't like the way the big monster looked. I am sure that it worked well but I went back to 3" K&N individual filters (just had room) and I feel that I am getting enough air. Not really sure what kind of clearance you will have with the bubbled bonnet but make sure that the front carb has room for clearance (surely you discussed this with Richard before the purchase). I actually had to move the brace on the right underside over about 4" inboard, and went ahead and had that area of the bonnet over the three carbs louvered. That, of course, won't be an option for the Michelotti bonnet. It is interesting but the shafts on the triple setup are vitually touching each other and are linked with two spring connectors. There is zero play or spring between the shafts thus when you adjust one, you adjust all for idle. Very easy to keep the little monsters tuned. Too, you will only be able to choke two of the three but that works well. Have fun.

Bill
 
I have Richard's cam on order, plan to do the head along with it. Ran out of add-ons for performance, now time to open her up and really get going.

Bill
 
Dave: I read your post with interest. I wonder which model Stromberg your contact was thinking of. There were two models used, the earlier being the C3150, which I have on my car. The entire hex plug and jet assembly unscrews right out of the carb, like the earlier ones. Perhaps he was referring to the jet bushing, which the jet passes through. In fact I can quasi-adjust mine by screwing the hex plug out which lowers the spring loaded jet. This was not meant to be used as an adjustment measure, but a few turns out doesnt seem to hurt. This lets you enrichen the mixture but does nothing the lean it out if you have run out of adjustment, which is my problem as one of the jets is worn. Burlen in the UK has new jets, as I just discovered on their website. I am still going to look for another set of 3150 carbs to experiment with. Let us know how your setup goes, I for one am very interested in doing the same!
Regards,
Andy
 
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