Fuel Injection Timing- Static versus Dynamic October 11, 2020 07:30AM
We have a 5.9 Cummins and are running a Stanadyne rotary pump and I am confused on the injection pump timing. I compared an injector timing light that clamps to the #1 injector line to the static timing based on the marks in the pump. There is a major difference, the static timing is about 20 advanced compared to the dynamic timing. Also the engine seems to want more timing, I say this because we get little black smoke and the exhaust seems to have raw fuel in it.

Has anyone compared a timing light to static timing on a Stanadyne rotary pump?? If yes, what did you find?

Re: Fuel Injection Timing- Static versus Dynamic October 11, 2020 08:11AM
Sounds to me like you are 180 degrees out of time. Double check make sure both valves are closed and piston is coming up on compression and not exhaust. Sounds like it to me.

Re: Fuel Injection Timing- Static versus Dynamic October 11, 2020 08:17AM
That is a good point, I have checked timing with the valve cover off and both valves are closed, so I believe we are correctly timed. The engine starts well and we made decent power at the track, but had excessive pre-turbine temps.

Re: Fuel Injection Timing- Static versus Dynamic October 11, 2020 08:42AM
excessively slow timing and 180 out timing will give you the same high exhaust temps the same. Its because raw unburnt fuel gets into the exhaust side of head and into exhaust manifolds. I would still double check and make sure that timing mark in window of pump is lined up and you are coming up on compression with piston. I know you said both valves were closed. However on exhaust stroke, both valves will be close to being closed as the piston nears the top but not completely closed. As the exhaust is closing the intake is opening to begin intake stroke.

Re: Fuel Injection Timing- Static versus Dynamic October 11, 2020 09:56AM
OK

Re: Fuel Injection Timing- Static versus Dynamic October 12, 2020 03:13AM
Timing lights and Roosa pumps don't mix. The beginning of injection is variable depending on load on a Roosa or CAV pump. It is not 180* out of time, it will not run as good as it does. They may run by starting with ether, but never make enough power to pull themselves, much less sled pull lol!

Re: Fuel Injection Timing- Static versus Dynamic October 12, 2020 04:15AM
That sounds like the missing link in this thought process, I believe the start of injection changes as the injection duration changes with load. It would be interesting to see a fixed RPM plot of load versus start of injection and load versus injection duration.

Re: Fuel Injection Timing- Static versus Dynamic October 17, 2020 07:20AM
Put a marked balancer pulley on the crank and a pointer. Loosen number one injector line at the injector and roll you engine over when fuel drips out the line this will be your timing at the crank marker

Re: Fuel Injection Timing- Static versus Dynamic October 18, 2020 12:49AM
That is a different way of checking timing, but it makes sense.

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