My Zenith Stromberg metering needle adjusting video
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- čas přidán 7. 09. 2024
- 1979 Triumph Spitfire 150CD4T, tag number 3961 (1977 onward). My engine is rebuilt, new gaskets, no vacuum leaks or timing problems. I had some soot on my spark plugs, on the first thread ring. The book said that soot on the ring indicated the carb was set rich. I don't have a CO analyzer, so adjusting the metering needle was my next step. Elevation here is at 4,350' my metering needle is a 45N. The 45M is for high elevations (plan to change later). I'm adjusting for best needle position with the engine at running temperature, to see if the soot will clean up. I changed spark plug heat range, using NGK BP6ES now, for 9:1 compression ratio engines. The California CR was lower at 7.5:1 and used a hotter heat range spark plug. I was hearing pre-ign/det with those hotter plugs, another video. Zenith-Stromberg Adjusting Tool for the metering needle. allen with the guide that holds the rubber center from twisting. Zenith-Stromberg carb parts suppliers should have this in stock, possibly with their own name for it, but that is what it does.
great video thank you. I am currently restoring a 78 myself after its been locked away fro 20 years. i hope to learn a lot from you.
Actually, your going to learn a lot from that 78.
When you turn counter clockwise, does it mean the needle goes down and less fuel going in (leaner)?
@@QuangWynn2711 Yes. Clockwise is richer, pulling the needle up. Just remember left for lean and right for rich.
I try that but not helping at all .
Thanks heaps for this Calvin.
Cruising the higher elevations above 6000, I found the engine acted up when driving around in 2nd at low rpms. Further needle adjusting leaner corrected that, and it was around 2.25 CCW total adjustment when I finished..
Thanks a ton for this video!
Interesting, maybe this adjustment is what mine needs. I have a 1978 Spitfire and the only way it will run is to take a piece of thin cardboard and completely cover the air intake. Once it's running I can move it enough to let more air in and it runs fine. If I remove the cardboard the engine dies.
Check the float bowl fuel level, if the level is too low the fuel is not up into the jet as needed. The cardboard is causing the engine vacuum to pull fuel from the carb. Cleaning all carb passages is the next step. You should not need to block the opening.
Calvin, whe I try to turn the allen key there is a massive amount of resistance to the movement of the tool. what could be causing that..?
Chris, If turning the allen clockwise, the tool is turning a screw in the piston, as the screw raises the jet needle the screw runs out of thread, and bottoms out. Counter-clockwise extends the reach, and will turn out from the needle, turning free till it releases the screw, and separates.
Great video! I have stromberg 175cdt-u for Mercedes 1978, I've try to adjust mixture but when I try to lift the valve up the idle drop & engine is shut off. The rpm is already on the high idle. Is there other screw to adjust the idle? I have no problem with the power of my engine but when I checked the spark plug its full of carbon (Back then my spark plug is brown & fuel economy is great)
Adiemobs, I'm not familiar with the175cdt-u. Spark plugs covered with carbon is usually too much fuel, could be the choke not fully releasing. My water heated choke was causing me trouble so I installed the manual choke. This carb in my video here is running with the 10% ethanol blend fuel, engine ran well. When the non-ethanol mix fuel become available again I overfilled my tank (my bad) in Montrose before driving from over Red Mountain (twisty high elevation roads). When I got home I found the carbon canister was soaked with wet gas, and my spark plugs carboned up the worse I had seen. I cleaned the plugs and used the ethanol mix after that. Engine ran better, no heavy carbon build up. I edited most of my earlier reply out, sometimes too much info is confusing. You had good coloring before, could be something you recently changed. My 150 did have another screw, on the rt side of the carb, for adjusting the mix when smog testing. I think it was fine tuning the internals I'm not sure. Mine was set a few turns out. My choke was most of my troubles.
My car runs very rich, should I turn Clock Wise to make it leaner?
Calvin, all the way clockwise the needle stops, will it stop if adjusted far enough counter clockwise. Mine just spins and spins…Wondering if my diaphragm is ripped.
you can drop out turning it CCW, just lift the piston up with your finger and turn the adjuster CW to pick it up again. I check my diaphram while it is out, gentle stretch and a light behind it would show through a hole.
So I just installed my carb and it revs like its wide open throttle. I've checked the cables, the carb at rest, the gaskets are new and the bolts are tight. Where do I begin from here? And what's that port above the mouth of the carb?
Jim, gasoline makes the engine rev higher, check the float level setting, piston needle position, choke fully off? Look at where that port goes and what it effects on the carb.
Like I said the cables are at rest, no pulling. It revs like the throttle is wide open, high enough I dont want leave it running to red line the RPMs. I know Kehin and Makuni carbs just not zenith. I assume the opening above the mouth is idle air intake ? I can see as much as when I fire off the slide is still down.
@@jamesteeter5345 Throttle and choke cable at rest. So something is holding the throttle open. The fast idle adjuster screw or choke screw holding carb butterfly open. Raise the piston, look into the carb see if the butterfly is closing or if the metal plate is off center contacting the side of the throat. If throttle or choke screw adjusted tight turn that screw counter clockwise to close the carb butterfly. I swapped a butterfly plate from another carb, did not fit correctly, so it was holding the carb throttle from closing.
If the idle speed slows or stumbles when the piston is slightly lifted, the mixture is too lean.
Don't forget to watch the spark plugs after making mixture adjustments. Assuming there are no vacuum leaks or open lines into the intake manifold for air to lean the fuel mix. If the electrode's insulator is white after driving awhile, either the plug heat range is too hot (burning off all the fuel trace, aka color) or the mix is a bit lean. Dropping in spark plug heat range should bring back some light brown color, letting you know your in the right heat range. I find these carbs and cars have more than one problem happening when it comes to proper spark and fuel. A very lean mix can cause hotter running engine temperatures, not the best thing for aluminum pistons.
Indeed, Sir. After i fitted a "sports filter" on my car, the Zenith did´nt get enough vacuum so it just got too much air. Plugs looked like they had´nt been runing at all afler several miles.
When you turn counter clockwise, does it mean the needle goes down and less fuel going in (leaner)?
CW is up, more fuel.
Yes CCW is down, less fuel, lean mix.
I have a Stromberg 175 CDT on a car in Europe that's runs terribly when you hit the gas hard. Also doesn't want to idle. Assuming I get the fuel system cleaned out and it still runs the same what would you look for?
I would guess that the diaphragm has a tear. It would be best to get a carburetor rebuild kit for it.
Triumph Spitfire & GT6 Forum
My idling speed is way to high on my w123...which parts should i adjust? Im using zenith cd150
3 places to check: throttle cable adjustment for proper slack, choke adjusted correctly off, and the idle screw on the left side near the choke that moves the throttle. There are vids on UT of those items, and the web has pictures of the carb's left side screws named. Your manual is very helpfull, it you don't have one ebay does.
Is this needle - once in right position - fixed to the round cilinder or can it still move in and out?
fixed to the adjustable screw you adjust in the top using an allen wrench and special tool preventing the inner diaphragm from turning.
isnt there an extra air screw that says to not touch it. i would adjust that after you have adjusted the main jet.
CO needle is on the radiator side of the carb, is that the one your referring to?
actualy i dont own a car like this but i only know it by my neighbors car. in that one its burning too rich like the choke is on. spark plugs are black. he doesnt know what to do. since i have a diploma in mechanics i have a good idea. he adjusted the main jet and did not do anything. there are only two other adjustments. one says do not adjust and another one beside it. one of those is the one thats adjust the total air through the whole opening range of the main flap. and yes try the co adjust see what it does you cannot hurt anything cus only adjusting air and fuel! the neighbor is too scared to touch them! its better than running that engine rich. cus that causes carbon buildup! not good!
im a new mg owner..what tool are you using to make those adjustments
It's a special tool - Google "Stromberg adjustment tool" and it'll pop up. Costs about $13 on eBay.
I just ordered my metering needle tool today, but before I mess with it I've noticed something John Twist said about the needle. There is a pin inside that if it's missing will allow the metering needle to spring up into the valve. (Which mine does with about a 1/4" of play.) Where would this pin be? He says a piece of paper clip works fine to replace it. How much movement of the needle is normal and why is the spring in there? On the SUs on my Z car the needles are solid in the pistons and no diaphragm.
the pin is touching the top of the needle, the needle sits on a spring, all 3 are part of the needle holder. That is why you can pull the needle down about 1/4". The needle holder threads onto the allen wrench adjuster screw.
Just got done messing about with it. Either my needle and jet are very worn or I have a mismatched pair. I placed a copper shim between the needle and adjusting screw so the needle is pushed all the way out of the valve assembly and down into the jet. It still blows a little smoke, but it will at least hold an idle and it didn't load up while holding 55. I think my understanding of the mixture may have been flawed as well. When you adjust the screw, the boss that the needle (and the jet it goes into) never change relation. So you aren't reducing the fuel metered into the engine by running the needle into the jet (as I have done with my shim), you are increasing the airflow by actually raising the piston with the needle valve assembly to allow more air into the mix. Am I correct in my new understanding? Either way, I'm looking for a new matched needle/jet assembly as the needle is very sloppy in the bore of the jet.
No your not correct, adjusting the needle with the allen tool is not supposed to raise the piston, air flow across the bridge under the piston causes the piston to lift, and pulse up & down. A CCW allen turn moves the needle down into the jet or CW up but not out of the jet. Think of it as a tapered rod and the taper is blocking the fuel more and more as it goes down into the jet hole causing the mixture to air to be leaner. The adjuster can detatch from the needle holder when your turning it CCW, just lift the piston and turn the allen CW and it will reconnect. Other things can cause the exhaust to smoke some too, oil leaking down the valve guides, a mis adjusted float if too high will raise the fuel level into the jet, air valve on the carb gaskets, ect ect ect. U-Tube is not the best quick answer, try the spitfire>6 forum, usually someone is online and help out. Be sure to post the year of the car in question, it helps.
I've been viewing the University Motor vids on the Stromberg as well. I have adjusted the float and auto choke per John's instructions. The only thing I can't figure out is the needle valve. If you turn it clockwise it will pull the whole assembly up into the damper which opens up the jet, but the needle assembly can't go any further than flush with the bottom of the damper. (I've had it completely free from the piston to check its fit in the seat which was very sloppy!) After that the shoulder of the needle valve assembly is making contact with the top of the bridge and the only thing left to happen is for the piston to raise. (This being when it is not running that is.) At least this is what is happening on my car. (78 Midget 1500.) Is the shoulder of the needle valve assembly supposed to fit inside the large hole in the jet so the actual needle can descend into the smaller hole further down in the jet? My needle says 45O but I may be misreading it as the only ones I can find at Moss are 44A, 45K, Q and R So I think I probably have a 45Q. I can't find a seat at all. I will be replacing my diaphragm. Even though it doesn't look like it has holes it still may have them. John had one off of the carb from a TR6 and he had stretched it so we could see the perforations. Thanks for suffering my lack of knowledge. I will say I like my SU's On my 260Z much better! Even though they operate on the same principal, they just seem easier to understand!
When mine is flush, I can adjust it higher into the piston. I don't recall mine adjusting so far down it hits anything, before disconnecting. I have adjusted mine up to richen my mix. If your adjusting it down your trying to lean out the mix. Is the jet too big, is the needle/jet a matched pair, did someone drill it larger, or is it just worn out ? Has it been taken apart and reassembled before, and did they not use the correct parts ? Slow answers to more questions. Like jpatt, I find youtube limited in what it can do. A video gets published, more questions come up, then we spend more time searching, viewing, and still have unanswered questions. I recommend the Spitfire & GT6 forum. On the forum, your not waiting days for answers, and photos can be posted to help show solutions. I find multiple answers to some questions because problems can have multiple causes. Hope to read more questions about this carburetor on the forum jpatt.
What's procedure on 2 carburetor set up
Zenith Stromberg owners workshop manual.
You haven't O-Ring on cover piston ?
boot is seal
What is the yellow screw on the right of the carb? I know I need to adjust my carb as it is running really rich but I cant figure out what that yellow knob does.
that plastic cover is on the fine adjust screw for air/fuel mix. It is only adjusted when a gas analyzer is connected to the exhaust to check carbon monoxide levels. If your engine has the smog equipment still working. If the engine does not have pollution testing in city, the screw is not used.
Thank you!
Where can I get This ajusting tool? Whats that tool name?
Zenith-Stromberg Adjusting Tool for the metering needle. allen with the guide that holds the rubber center from twisting. Zenith-Stromberg carb parts suppliers should have this in stock, possibly with their own name for it, but that is what it does.
Calvin, thanks for the detailed video. I just ordered this tool today, but I got to thinking there might be different ones (sizes) for different cars/carbs? I couldn’t seem to find any differences in the ones I found. Is there just one version? I have the Stromberg 175 Cd for 1964 TR4...
@@timduncan1282 I would talk with that sales person about that to be sure. I don't have a 175 to check myself. 175 is 1/4 inch wider out, piston should be a tad wider, but it should be the same allen. I have the 150, not much different in size.
What in the world are you doing? Hard to read your mind sir.
You can read the spark plugs to see if your running too rich. If your plugs are too hot, run too white, change to cooler heat range. Fuel mix instructions at sea level change with elevation change. I adjusted leaner for higher elevation. Plugs are cleaner, MPG improved, engine response improved. The engine stopped running rich when I crossed 10,000 elevation summits.
Jess, short answer is: I'm adjusting the air to fuel ratio for my elevation. I had removed the Calif epa restricted camshaft and installed the MKIII higher performance camshaft in 2015. I did not change the needle attached to the piston, just the position of it to the jet by turning the adjuster with the allen tool. HTH