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Stromberg high altitude metering needles

M

Michael M

Donation Time
Does anyone know the needle number for the Stromberg high altitude (5000-10,000 foot) metering needles.

I would like to locate high altitude needles to experiment with here in Denver Colorado. Colortune shows my 67 Alpine is running rich at anything above idle.

The parts catalog shows the standard needle as a 5M with Rootes part number 5113831.

No 5M type number is shown for the high altitude needle but the Rootes part number for the high altitude needle is 5058887.

I have the "Haynes Weber Carburetor Manual Including Zenith Stromberg and SU Carburetors" that shows Stromberg needle sizes in appendix 4. Using that data I could make a guess at which needles might work but I would like to know what Rootes recommended or what someone is actually using successfully.

Michael
 
R

RootesRacer

Donation Time
Michael M said:
Does anyone know the needle number for the Stromberg high altitude (5000-10,000 foot) metering needles.

I would like to locate high altitude needles to experiment with here in Denver Colorado. Colortune shows my 67 Alpine is running rich at anything above idle.

The parts catalog shows the standard needle as a 5M with Rootes part number 5113831.

No 5M type number is shown for the high altitude needle but the Rootes part number for the high altitude needle is 5058887.

I have the "Haynes Weber Carburetor Manual Including Zenith Stromberg and SU Carburetors" that shows Stromberg needle sizes in appendix 4. Using that data I could make a guess at which needles might work but I would like to know what Rootes recommended or what someone is actually using successfully.

Michael
Click to expand...

Stroms in good condition will work fine at 5000 feet even with the std altitude needles.
You need the special needles (which you will never find BTW) for sustained driving at or near 10k feet.

In any case it is far more likely that you have a manifold leak or worn throttle spindles, which causes unaccounted manifold airflow at idle, causing you to put the main jet in an unacceptable location for main running. Common worn strom problem.

You will need to rebuild your carb (with new or reworked spindles) or switch to a different carb setup. Most folks prefer the latter but stroms can be made to work fairly well.


HTH
 
Mark B

Mark B

Donation Time
Michael-

I fairly routinely take my Alpine over some good passes here in Colorado and I love the fact that, unlike some of my previous cars, they do not slowly go rich and fail to idle, drop a ton of power, or gas me with huge fumes. I went up to the visitors center on the Peak to Peak above Estes this year and they ran like champs at 10-13K, unlike a few of the motorcycles I followed.

Racer is correct in that Stroms must be set up well to perform well. A can of carb cleaner with those red straws and some very careful spraying can help identify if you have intake gasket leaks or worn spindles, or other air leaks that cause symptoms like you describe. The drop test to "thunk" the pistons also identifies another common issue and will then point to worn needles or the "ring" seat the needles float within.

I always start with adjusting valves, timing and then working on all the subtle things that make Stroms idle well and pull through the range.

Good luck with the issue.

Mark B
 
M

Michael M

Donation Time
air leaks

Thanks Mark!

The Alpine actually idles and runs very well, thanks to RootesRich who was good enough to check my work of valve adjustment, timing, and carb adjustment. Thanks RootesRich!!

It does show more yellow color when observing the combustion using "colortune" type of spark plugs than is desirable. Rich did the carb cleaner spray test on the spindles and heard a slight change. The leak did not seem bad enough to warrant a rebuild of the carbs. I do not think we checked the intake manifold gaskets.

I was hoping to just compensate by dropping different needles in and readjusting.

The Alpine is running well enough that I will likely finish this Colorado "driving season" as is and chase the leak next year.

Thanks
Michael
 
B

beamdream

Gold Level Sponsor
Michael M said:
Thanks Mark!

The Alpine actually idles and runs very well, thanks to RootesRich who was good enough to check my work of valve adjustment, timing, and carb adjustment. Thanks RootesRich!!

It does show more yellow color when observing the combustion using "colortune" type of spark plugs than is desirable. Rich did the carb cleaner spray test on the spindles and heard a slight change. The leak did not seem bad enough to warrant a rebuild of the carbs. I do not think we checked the intake manifold gaskets.

I was hoping to just compensate by dropping different needles in and readjusting.

The Alpine is running well enough that I will likely finish this Colorado "driving season" as is and chase the leak next year.

Thanks
Michael
Click to expand...

Have you considered dropping the float levels a tad ?
 
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