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HIF 550 Carburetor Float Bowl O-Ring Seals

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2003JAG Avatar
2003JAG Gold Member Chuck Hassler
Monument, CO, USA   USA
1968 MG MGC "Blue Boy"
1980 MG MGB Limited Edition (LE)
Replaced the HIF 550 float bowl lid seals today. The old float bowl lid seals were of two designs; one was a round seal and the other was the square type provided in rebuild kits. None of the seals were leaking, just time to clean the carbs and replace rubber parts. The round seal looked like it filled the float bowl lid seal channel better. Anyone have a problem with a new square seals leaking?

Chuck

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barry s Avatar
barry s Silver Member Barry Stoll
Alexandria, VA, USA   USA
1972 MG MGB GT
1974 MG MGB
1976 Triumph TR6
1980 MG MGB
They both work if lids have not been deformed by over tightening. Generally the square profile are preferred.

2003JAG Avatar
2003JAG Gold Member Chuck Hassler
Monument, CO, USA   USA
1968 MG MGC "Blue Boy"
1980 MG MGB Limited Edition (LE)
Thanks Barry!

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PaulP Avatar
PaulP Gold Member Paul Peterson
Seattle, WA, USA   USA
1973 MG MGB GT
1974 MG MGB
I started my '74 for the first time in 3 months last weekend. I got halfway out of the garage and got a strong smell of gas. Turned out the float bowl on the rear carb was leaking (significantly). The carbs were rebuilt in ~'06. The seal I pulled out was round. I had an old rebuilt kit on the shelf with a square cut seal. It worked fine.

barry s Avatar
barry s Silver Member Barry Stoll
Alexandria, VA, USA   USA
1972 MG MGB GT
1974 MG MGB
1976 Triumph TR6
1980 MG MGB
In my experience, the bowl cover seals/o-rings fail by becoming brittle over time. Removing and replacing the cover and reusing the same seal can accelerate this process. I think that the square profile may have a bit longer anticipated life that the round ones.

riley1489 Avatar
riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
Com'n chaps ...............

If the SU carburetor designers had called up a round section 'O' ring for this cover then the groove in the cover would have been machined accordingly. Use the correct square/rectangular intended seal.

Don't tempt fate, The SU instructions tell all. (below)

B



Check your ego Amigo!



Edited 1 time(s). Last edit at 2018-03-14 07:22 AM by riley1489.


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BH_HIF_seal.JPG    10.4 KB
BH_HIF_seal.JPG

Steve S. Stephen Strange
Harrisonburg, VA, USA   USA
1972 MG MGB MkII "The Mouse Trap"
Chuck-
I have to go with Bruce on this one. I have a spare rebuild kit that I ordered from Burlen Fuel Systems, the SU manufacturer over in the UK. It includes a square-cross-section sealing ring for the float bowl. That makes good sense, since it gives a larger sealing area than a round-cross-section O-ring would.

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