How to Tune Stromberg carbs?

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arcticrover
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How to Tune Stromberg carbs?

Post by arcticrover »

I have taken apart and cleaned my Strombergs and will be reassembling them as soon as the gasket kits arrive in the mail. What steps will I need to take to ensure that they are properly tuned? In the meantime I am working on polishing the carb tops. . .on the third application right now and only beginning to get somewhere.
glencoyne
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Post by glencoyne »

Strombergs in good condition should be reasonably easy to set up. A few things before you start:

1. While you have the carbs in bits, if they have the little spring loaded valves in the throttle discs, clean them up and then solder them shut using soft solder and a blowtorch. Otherwise you will never get the idle speed down to a sensible level.

2. It is worth replacing the needle and jet in each carb as they wear over time, making it impossible to set up the mixture correctly.

3. Make certain that all your ignition settings are spot on before you try to set up the carbs.

While you have the carbs in bits, set the needles so that the shoulder of the needle is level with the bottom of the dashpot. This provides you with a known starting point. Needle height is adjusted using a special tool which pokes into the top of the carb after unscrewing the damper piston.

After that, adjustment is 'by the book' and too complicated for me to go through here. Balance carbs and set idle speed first, then set mixture, then adjust idle speed if needed and recheck balance. You need to be patient and methodical. You may have to go through the loop of adjusting idle, then mixture, then idle, a couple of times before you get a setting you are happy with. Just remember (because the book probably won't tell you) that you screw the needle clockwise (with the special tool, looking from above the carb) to richen the mixture, anti-clockwise to weaken it.

Richard
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arcticrover
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Post by arcticrover »

Richard-

I will have to take a look through my manual to figure this all out. Thanks! What is the "special" tool? It looks as if a hex wrench belongs here?

Bobby
glencoyne
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Post by glencoyne »

If your vehicle has been fitted with carbs from an earlier Range Rover, they may have external jet adjustment, in which case you don't need a special tool. I found this page which explains the difference between the various Strombergs, and also how the special tool works:

http://www.roverklubben.se/stromberge.html

Richard
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arcticrover
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Post by arcticrover »

hmmmmm. . . .i took a long look at my damper cap and i'll have to try and describe it, because my wife stole my camera. the hole in the center of the slot in the plastic cap is perfectly round (not hex) and the (metal?) that I can see at the bottom of the hole has no pattern, grooves, inset, etc. It's just flat. I'm not sure if that tells me which carb I have. I did happen to find a decent stromberg/su technical specification from volvo. It might be worth a look.

http://iai.eivd.ch/users/fwi/cars/docs/ ... tuning.pdf
glencoyne
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Post by glencoyne »

You have to remove the damper cap and piston altogether. You then insert the special tool into the cylinder that the damper piston sits in. The tool has two parts - a central rod which engages with the upper end of the jet and screws it up and down relative to the dashpot, and an outer ring which engages with the top of the dashpot, to prevent it from turning when you adjust the jet, and tearing the rubber diaphragm. You hold the outer ring steady and turn the central rod to adjust the mixture.

Richard
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arcticrover
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Post by arcticrover »

Wow. Now the idea is coming together. I looked at the clyinder/needle have the idea down now. Now to find the tool . . . .
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samro
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Post by samro »

best way to tune sromburgs is to take them off & fit Su's!
"The very difficult we do immediately the impossible takes a little longer!"
1985 Range Rover V8 Auto [Rachel]
1981 Stage 1 V8 S/W [Custard]
1972 SIII 88" D S/W [The 88"]
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Basil
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Post by Basil »

I coudn't agree more, su's are far better than stromberg's
Landrover, If it don't leak oil, it's ran out.

Stage1 station wagon, 3.9 V8, galv chassis, parabolic's, lpg
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arcticrover
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Post by arcticrover »

I'm only concerned with getting these running to pass emission inspection. As soon as I get my two year sticker, I will be removing the whole setup and putting on my Edelbrock Mani with 470CFM off-road carb. I like the duals, but they are just too finicky versus a single modern carb.
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Post by primsil »

My rangie has SUs off a p6 but Im not happy with them. changing to a 2bbl holley soon. My stage1 will get the Edelbrock treatment.
1985 110, 3.9 auto
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arcticrover
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Post by arcticrover »

I can't wait to see how mine will perform with the Edelbrock/Holley stuff installed. It will most certainly need some brake work. By the way, after four runs on the old carb top with Brasso and a Dremel buffer I wasn't getting anywhere, so I decided to paint instead. . . I am not overpleased with the results, but it seemed to turn out allright . . .

Image
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Post by primsil »

I use 8" rag buffs that mount on a spindle on a 10" grinder, coarse and fiine mops and polish, does take a bit of patience though.
1985 110, 3.9 auto
llandes
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Re: How to Tune Stromberg carbs?

Post by llandes »

Hello, New member here from California.

I just bought a Stage 1. 1983 5 door. The truck needs some work and runs terrible at low rpm. I'll set timing first, but I'm certain I have carburetor issues. Is there a step by step tuning manual available anywhere for the Stromberg Zeniths? I've done the "idle, mixture, back to idle, back to mixture" set up on other carbs before but don't know how to get familiar with these carbs before I jump in. Any manual or step by step tuning or exploded drawings would really help me.

Thanks in advance for any assistance or guidance.

Cheers...

I'd attach an image, but clicking on "Img" doesn't seem to allow me to do so... Sorry.
disco2hse
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Re: How to Tune Stromberg carbs?

Post by disco2hse »

http://lmgtfy.com/?q=how+to+tune+stromberg

or Ron has provided this:
http://p38arover.com/misc_files/Tuning_ ... _Carbs.pdf

PS, it is better to start your own thread than hijack another when you have a new question. You might also like to take the opportunity to introduce yourself.
Alan

1983 ex-army FFR 109 Stage 1
2005 Disco 2 HSE TD5
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