Good evening everyone,
UPDATE 29.3: The constrictions are at the end of the metal pipe feeding the carburetors , the hole is relatively large with near 3mm diameter. Thanks to Colin on UK Forum) I added a photo, last one
Related to a previous post of mine, this is the scheme of the US crankcase ventilation I found on the UK site.
I disassembled the pipes connecting the carburetors to the crankcase ventilation. The whole pipe from crankcase to the Strombergs is about 8-9 mm internal diameter, including the Stromberg entry point, just after the butterfly (that surprises me, I never expected to see such a large opening in that part of the carburetor )
On the A bank, the rubber elbow connectors to the carburetors had a 5 mm hole venting the carburetor to the atmosphere (!) . The upper part, to the metal pipe connecting to the other bank and to the crankcase, was blocked by a ball from a bearing (Only on the right side) . Courtesy of a previous owner, as rightly suggested by @MarekH
. Purpose unknown.
I have installed new elbows at the Strombergs entry points, but the engine developed a ´sinusoidal´behaviour when idling, with rpm increasing, then decreasing, the amplitude increases until it then stops. I kind of understand this: increased rpm, more blow-by gases, incrased rpm, then mixture gets leaner , rpm drop, gets richer again and the cycle goes on until in one cycle the mixture is so lean that the engine dies. Will re-check carburetors balance now that the air leak on the rubber elbows in Bank A is gone.
By the way, instead of the elbows I used a 10 mm internal diameter gas pipe and it works fine. If you think SNG sells each elbow for 18 USD . That makes 180 USD / meter of regular gas pipe …
Many thanks
Rui
(before , it had only a very slight sinusoid idling behavior)
Also , this.is how the connection.to the cannister looked like . There is a tiny conical filter that was of course obstructed . You may want to check yous, this will prevent the canister to work as it should and lead to gas smell in the garage .
Up, the restrictors on the pipe connecting to the carburetor rubber elbows.