Posted By: Uberpube
Tuning the 440 , industrial style - 10/29/22 02:14 PM
I got a chance to work on 440 running on natural gas that is on an emergency backup generator. This machine hasn't been able to pass a load test for a while. It had a full tune up, plus points changed out for mopar electronic kit, but was still failing. This is essentially dyno testing the motor at a fixed speed (3600 RPM).
Ran the machine as is, runs perfectly fine at idle, but slowly bogs down and powers out as load as added, producing around 27 kw.
I inspected the first set of spark plugs(brand A), showed same color as new spark plugs(Brand B), and motor compressioned out at 110 psi hot, engine is stamped as 1977.
After a few checks and fiddling doing nothing big, getting to 30 ish KW , I convinced the owner to let me change the plugs to a different Brand, brand C. Machine now produces and holds 47 kw. We make a change to
the fuel pressure, we get 54 kw, we got our hands on a new mixer and the machine makes about 60 kw watts, which is the derated for altitude spec for this machine which is now about 42 years old.
Brand C is NGK.
I learned quite a bit about vapour fuels from that, even when we found it was overly lean, it never popped back through the carb like a gasoline motor would, and it never stumbled either, it just reduced the overall power output. Interesting that they only carb'ed a 440 with a 388 CFM carb as well. The engine got hotter making low power with bad mixture and plugs than it did once it was running at full power, which was interesting, I am assuming a lot of unburnt fuel combusting in the water cooled exhaust manifolds.
Ran the machine as is, runs perfectly fine at idle, but slowly bogs down and powers out as load as added, producing around 27 kw.
I inspected the first set of spark plugs(brand A), showed same color as new spark plugs(Brand B), and motor compressioned out at 110 psi hot, engine is stamped as 1977.
After a few checks and fiddling doing nothing big, getting to 30 ish KW , I convinced the owner to let me change the plugs to a different Brand, brand C. Machine now produces and holds 47 kw. We make a change to
the fuel pressure, we get 54 kw, we got our hands on a new mixer and the machine makes about 60 kw watts, which is the derated for altitude spec for this machine which is now about 42 years old.
Brand C is NGK.
I learned quite a bit about vapour fuels from that, even when we found it was overly lean, it never popped back through the carb like a gasoline motor would, and it never stumbled either, it just reduced the overall power output. Interesting that they only carb'ed a 440 with a 388 CFM carb as well. The engine got hotter making low power with bad mixture and plugs than it did once it was running at full power, which was interesting, I am assuming a lot of unburnt fuel combusting in the water cooled exhaust manifolds.