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Old 10-11-2019, 10:27 AM
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tgreese tgreese is offline
Join Date: May 29, 2003
Location: Medford MA USA
Posts: 11,203
Originally Posted by aerocorey
Do you think the vent pressure would exceed 1 PSI?
No. The bowl vents are always open to the air horn (top area of the carburetor, inside the air cleaner). When running, the solenoid valve is closed and the bowl vents are active. When the engine is off, the cold air door comes down to block the air cleaner snorkel, and the solenoid valve opens. The canister is now a less restrictive path for the vapors to vent, but no way is the air cleaner door going to seal enough to hold 1 psi of vapor pressure.

I think TW's advice is good - just block it and leave it in place if you need to retain factory appearance. If you worry, you could block open the cold air slightly and let the vapors from the bowl vents freely vent through the cold air intake.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination ATs, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
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