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Author Topic: SU Float Levels  (Read 1759 times)

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  • American MGB Association
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  • American MGB Association
    • American MGB Association
SU Float Levels
« on: May 06, 2018, 06:35:08 PM »
I have twin SU HS4s on my MGB and Im very confused about Float levels. The needle valve is spring loaded, NEW,  and the manual  tells me I should use a 1/8 inch drill bit to set the level and the gas level in the bowl  should be just below the jet.
The problem is the float level without the spring compressed, as the manual says, is about inch and the float bowl  is about half the level it should be.
Any ideas?
Thanks and use your videos a lot!
D. Noel
American MGB Association
phone/text: 773-769-7084

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Re: SU Float Levels
« Reply #1 on: May 06, 2018, 06:49:02 PM »
The float height is measured without the spring collapsed.  Sometimes the spring is very weak and the weight of the float will collapse the spring.  In that instance, turn the float bowl lid from vertical to horizontal, stopping just before the collapse and check the height.

There are two types of floats adjustable and non-adjustable.  The adjustable floats often need the hinge tightened but they can be adjusted to whatever position necessary.  The non-adjustable hinge holes are sometimes badly worn requiring new floats.  If the float height is lower than it should be (your situation), remove the needle and seats and remove whatever washer has been fitted between the seat housing and the float bowl lid.  Refit the needle and seat and check again.  Sometimes you can tighten the needle and seat another turn to change the float height.  If all this fails, then use a sandpaper block and 80 grit paper to remove some of the plastic at the top of the float.  Do this slowly and judiciously, frequently checking the float height.

Hope this helps!

John H Twist
John H Twist
University Motors Online
100 East Beltline Avenue SE
Grand Rapids, MI  49506


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