Joe, I think the air/fuel mixture change for increasing the bore is not the problem. Diesel engines have essentially a fixed air intake volume for each revolution as there is no control of the air inlet as used on a petrol engine. The amount of fuel injected varies with the governor setting, thus the air/fuel mixture alters by a large amount between full power and low power (so rack position) and at low power the air fuel ratio is very lean. At full power the ratio should be approaching the ideal ratio between air and fuel. Excess fuel flow would cause smoking but this is more often caused by poor combustion, e.g low compression or defective injectors. I suspect your problem was due to the various throttle/ governor adjustments not being set correctly. The recent adjustment by the owner may give higher power but could be disguising other governor settings that are a bit off. I would recommend setting up the governor as per the Gardner Manual and then trying again.
Hi Joe I reckon something was sticking in the governor and twiddling the idle screw freed it off. For a given load the fueling will effectively self compensate since the governor will move the rack until the weights and springs are in equilibrium but a hair more throttle, hence a hair more fuel maybe required to achieve the desired RPM. Increase in displacement unless dramatic will only impact at full load conditions if the fuel system can longer deliver enough fuel to maintain desired RPM i.e you run out of rack travel. Remedy for this would presumably be higher capacity pump elements and / or injector nozzles. I think the previous comment is slightly incorrect presuming lean mixture at low rpm. Displacement is fixed however air flow behaviour is dynamic so at high rpm the mass of air in the combustion chamber will be very different to the mass of air at idle speed despite displacement being a "geometric" constant. I think this why you get a blast of black smoke when opening the throttle quickly, the fuelling increases pretty much instantaneously but the rpm and hence mass of air in the combustion chamber take much longer to build and get the fuel air ratio back where the designer intended. Just my view, I'm no expert either😂. Keep up the good work!
A 30 thou over bore will have a negligible effect on the air-fuel setting - I'd ask what has been replaced & whats been re-adjuste? it could be the new injectors more restrictive or higher pressure shut off though it's more likely to be adjustment
Hey Joe read the LW manual re setting up injection pump and governor linkage. That idle adjustment buffer stop has no effect on power or max engine speed.
We all know from our experience, of the huge difference in power that we get from having the mixture set exactly and so we know that this is very sensitive. On most engines we can do this by simply adjusting the fuel delivery until we hear the best pick up in speed and do it to suit each engine. Using this normal technique will give best performance regardless of the condition of the engine & injection system at that time, no matter what. The problem therefore, in this case, is simply finding or understanding, what is or was preventing you from adjusting the fuel delivery.
Bronze trunnion blocks and worn pins in governor weights, sticking governor weight sleeve, the 2 x small ball races in the end of the gov sleeve even a sticky gov spring sleeve will cause that problem. Seen LW pump tops on LXB's and they have a 6mm plunger against the LXB 7.5mm so therefore a lot less fuel with factory setting but engines still ran to its rated high idle.
Joe, I think the air/fuel mixture change for increasing the bore is not the problem. Diesel engines have essentially a fixed air intake volume for each revolution as there is no control of the air inlet as used on a petrol engine. The amount of fuel injected varies with the governor setting, thus the air/fuel mixture alters by a large amount between full power and low power (so rack position) and at low power the air fuel ratio is very lean. At full power the ratio should be approaching the ideal ratio between air and fuel. Excess fuel flow would cause smoking but this is more often caused by poor combustion, e.g low compression or defective injectors. I suspect your problem was due to the various throttle/ governor adjustments not being set correctly. The recent adjustment by the owner may give higher power but could be disguising other governor settings that are a bit off. I would recommend setting up the governor as per the Gardner Manual and then trying again.
Hi Joe I reckon something was sticking in the governor and twiddling the idle screw freed it off. For a given load the fueling will effectively self compensate since the governor will move the rack until the weights and springs are in equilibrium but a hair more throttle, hence a hair more fuel maybe required to achieve the desired RPM. Increase in displacement unless dramatic will only impact at full load conditions if the fuel system can longer deliver enough fuel to maintain desired RPM i.e you run out of rack travel. Remedy for this would presumably be higher capacity pump elements and / or injector nozzles. I think the previous comment is slightly incorrect presuming lean mixture at low rpm. Displacement is fixed however air flow behaviour is dynamic so at high rpm the mass of air in the combustion chamber will be very different to the mass of air at idle speed despite displacement being a "geometric" constant. I think this why you get a blast of black smoke when opening the throttle quickly, the fuelling increases pretty much instantaneously but the rpm and hence mass of air in the combustion chamber take much longer to build and get the fuel air ratio back where the designer intended. Just my view, I'm no expert either😂. Keep up the good work!
A 30 thou over bore will have a negligible effect on the air-fuel setting - I'd ask what has been replaced & whats been re-adjuste? it could be the new injectors more restrictive or higher pressure shut off though it's more likely to be adjustment
Hey Joe read the LW manual re setting up injection pump and governor linkage. That idle adjustment buffer stop has no effect on power or max engine speed.
When I was an apprentice the old boys used to file the "rocker arm" in the pump to increase rpm, not sure which bit, but it was common practice
We all know from our experience, of the huge difference in power that we get from having the mixture set exactly and so we know that this is very sensitive. On most engines we can do this by simply adjusting the fuel delivery until we hear the best pick up in speed and do it to suit each engine. Using this normal technique will give best performance regardless of the condition of the engine & injection system at that time, no matter what. The problem therefore, in this case, is simply finding or understanding, what is or was preventing you from adjusting the fuel delivery.
that applies to a petrol engine rather than a diesel unless you are talking about adjusting at max load?
Bronze trunnion blocks and worn pins in governor weights, sticking governor weight sleeve, the 2 x small ball races in the end of the gov sleeve even a sticky gov spring sleeve will cause that problem. Seen LW pump tops on LXB's and they have a 6mm plunger against the LXB 7.5mm so therefore a lot less fuel with factory setting but engines still ran to its rated high idle.
If you don't know what your doing seek out people who do know what they are doing ,gardener engines must have some mechanics still alive.
It would seem to me that a tight rebuilt engine compared to one with worn cylinders, would effect fueling requirements as well.
I wonder if you can install a P7100 on one of these.
Air density due to barometric pressure, temperature and altitude will have far far more effect on mixture than the 30 thou oversize pot....