djswain1
djswain1
- Joined
- Oct 3, 2017
- Messages
- 39
- Reaction score
- 22
Yup, I am learning the diesel jargon. It seems like the 2 most common mechanical types that are applicable to the diesel model engines are the (1) unit injector :located in the head, driven by a cam and rocker arm, with the pump and injector as a single unit, and bypass for excess fuel back to the tank. Correct? (2) Separate, matched pump unit and injector unit, with the pump driven off the cam shaft, and only the injector mounted in the head. I think that is right.
At the earlier urging of Bruce (I think), I purchased the smallest and cheapest pump and injector pair that I could find, to take apart and see what makes it tick. It seems like the injector and pump are the major bug-a-boo for model diesels. And seeing this is my first build, I have no qualms about, if it is absolutely necessary, machining excess material off the purchased items to install on the model. I know it is a cop out, but I am not copying any particular design and am a pragmatist, not a purist. Hopefully I won't have to do that, LOL.
Here is a pic of the "type 186" parts I bought, which probably put out 10 times the volume I need. You can see the volume control lever on the pump. I imagine it is more precision, than complicated. Each item is about 3" long.
View attachment 128760
Yes essentially, but there are lots of different injection systems and variations. Plunger pumps can be driven from the main valve camshaft or their own seperate camshaft. Small engines especially single cylinder usually have a separate plunger (or jerk) type pump injection like the parts you have purchased. The type 186 are copies of the Yanmar L series which is one of the most common "modern" single cinder air cooled industrial engines. It is a direct injection (DI) engine with a multi-hole type injector nozzle. The pintle type nozzle is probably the easiest design to use they are usually on indirect injection engines (IDI). You should be able to download an L series service manual which may have details if the pump & injection.Yup, I am learning the diesel jargon. It seems like the 2 most common mechanical types that are applicable to the diesel model engines are the (1) unit injector :located in the head, driven by a cam and rocker arm, with the pump and injector as a single unit, and bypass for excess fuel back to the tank. Correct? (2) Separate, matched pump unit and injector unit, with the pump driven off the cam shaft, and only the injector mounted in the head. I think that is right.
At the earlier urging of Bruce (I think), I purchased the smallest and cheapest pump and injector pair that I could find, to take apart and see what makes it tick. It seems like the injector and pump are the major bug-a-boo for model diesels. And seeing this is my first build, I have no qualms about, if it is absolutely necessary, machining excess material off the purchased items to install on the model. I know it is a cop out, but I am not copying any particular design and am a pragmatist, not a purist. Hopefully I won't have to do that, LOL.
Here is a pic of the "type 186" parts I bought, which probably put out 10 times the volume I need. You can see the volume control lever on the pump. I imagine it is more precision, than complicated. Each item is about 3" long.
View attachment 128760
IDI engine usually have flat top pistons and a pre-combustion or swirl chamber into which the injector injects. DI engines have shaped bowls in the piston crown with the injector, injectng directly nto the cylinder. Glow plugs can be used on DI & IDI.
Regards, Dave
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