MGB & GT Forum
vented oil filler cap.
 New Jersey, Oak Ridge, NJ, USA
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 Cambridge, ON, Canada
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Apr 21, 2024 01:02 PM
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 Joined 18 years ago
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 Great White North, QC, Canada
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Apr 21, 2024 02:02 PM
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 Geelong Victoria, Australia
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Apr 21, 2024 02:15 PM
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New Jersey, Oak Ridge, NJ, USA
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Great White North, QC, Canada
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Apr 21, 2024 04:24 PM
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In reply to # 4787705 by 74chromebumper
For pure aesthetics is why.
if that is the reason, get rid of the aftermarket downdraught and install dual SU.
B
Life's most persistent and urgent question is, "What are you doing for others?"
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Apr 22, 2024 02:37 AM
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Be careful messing round with the fuel tank vent. In the UK the tanks are vented through the filler cap. Just after I bought my GT I got a lockable filler cap from a well known MGB vendor over here. Couple of days later the car wouldn't start. It sounded like a lack of fuel but the gauge said 1/4 full. Being used to Austin Healley gauges I thought the tank must be empty. I undid the fuel cap and heard a rush of air into the tank. No mmore problems.
A few days later I was inspecting the underside (new car) and noticed that the bottom of the tank had lifted about an inch. The vacuum had destroyed a new tank.
There are two types of fuel cap. Vented for the UK and non vented for the US. They sent me the wrong opne.
AJ
A few days later I was inspecting the underside (new car) and noticed that the bottom of the tank had lifted about an inch. The vacuum had destroyed a new tank.
There are two types of fuel cap. Vented for the UK and non vented for the US. They sent me the wrong opne.
AJ
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IMG20220925122918.jpg 28.5 KB
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Apr 22, 2024 03:16 AM
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X2 on the filler cap being vented if the OEM venting system is dismantled. In my case the engine shut off, but the tank fortunately did not distort.
You can convert a non-vented fuel filler cap to a vented one by cutting a part of its rubber seal away, which I did in the end
Looking back I am still happy with the removal of the airpump, gulp valve and the attachment to the block, but maybe I should have left the venting from the gastank and the carbon canister as it was OEM. Still at the time the gastank needed renewal and at the time this special version was n.a. . Gastanks for a vented system not only have the attachment to the expansion gastank in place, but also possess a complicated internal modification
You can convert a non-vented fuel filler cap to a vented one by cutting a part of its rubber seal away, which I did in the end
Looking back I am still happy with the removal of the airpump, gulp valve and the attachment to the block, but maybe I should have left the venting from the gastank and the carbon canister as it was OEM. Still at the time the gastank needed renewal and at the time this special version was n.a. . Gastanks for a vented system not only have the attachment to the expansion gastank in place, but also possess a complicated internal modification
In reply to # 4787838 by mgtf328
Be careful messing round with the fuel tank vent. In the UK the tanks are vented through the filler cap. Just after I bought my GT I got a lockable filler cap from a well known MGB vendor over here. Couple of days later the car wouldn't start. It sounded like a lack of fuel but the gauge said 1/4 full. Being used to Austin Healley gauges I thought the tank must be empty. I undid the fuel cap and heard a rush of air into the tank. No mmore problems.
A few days later I was inspecting the underside (new car) and noticed that the bottom of the tank had lifted about an inch. The vacuum had destroyed a new tank.
There are two types of fuel cap. Vented for the UK and non vented for the US. They sent me the wrong opne.
AJ
A few days later I was inspecting the underside (new car) and noticed that the bottom of the tank had lifted about an inch. The vacuum had destroyed a new tank.
There are two types of fuel cap. Vented for the UK and non vented for the US. They sent me the wrong opne.
AJ
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New Jersey, Oak Ridge, NJ, USA
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Cambridge, ON, Canada
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Apr 22, 2024 04:38 PM
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My charitable donation:
Your engine breathes, like this:- Fresh air into the engine through the charcoal canister, therefore the non vent oil filler cap. Dirty air, including oil fumes/vapour, out through the combustion chamber via the tappet cover vent, slight vacuum required.
Oil as a liquid is supposed to be captured inside the tappet cover which is filled with a curly steel wool type material to facilitate this part of the breathing process. The tappet cover cavity should be cleaned out from time to time to prevent liquid oil from being drawn into the carburetor.
Edited 1 time(s). Last edit at 2024-04-22 04:46 PM by lewk.
Your engine breathes, like this:- Fresh air into the engine through the charcoal canister, therefore the non vent oil filler cap. Dirty air, including oil fumes/vapour, out through the combustion chamber via the tappet cover vent, slight vacuum required.
Oil as a liquid is supposed to be captured inside the tappet cover which is filled with a curly steel wool type material to facilitate this part of the breathing process. The tappet cover cavity should be cleaned out from time to time to prevent liquid oil from being drawn into the carburetor.
In reply to # 4787911 by 74chromebumper
Will do...right after I accept your charitable donation ! Like the old adage say, " If it ain't broke don't fix it". The car runs great with the Weber, no Cat, new exhaust and fuel tank. It sounds like I may go the route of a new vented filler. I might as well stir the pot some more... what is the advantage of leaving the tappet line to the carb only to have it accumulate a mist of oil? With a vented oil filler cap and leaving the canister line to the valve cover will that be redundant?
Edited 1 time(s). Last edit at 2024-04-22 04:46 PM by lewk.
Attachments:
BH_18V vents.JPG 71.3 KB
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