Injector Tip

[SHIPCHIEF]

I just removed one injector from my 25/2. That cylinder was lazy on start-up.
So I swung the injector line to the side, and reconnected the injector. I rolled the engine by hand and observed the injection event.
It cracked nicely, but sprayed off center.
I inspected the tip. It has a single hole, not on the center of the cone shaped tip.
The hole sprays a nice cone shaped fog of fuel, offset toward the fuel connection on the injector body.
Is this normal?

[LowGear]

Look at cylinder #2.

Casey

[SHIPCHIEF]

Good reply.
But I'm not home now and won't be until tomorrow. I was just hopping to pick up some advice from someone who has been there already, so when I get back at it, I'll be a bit more prepared.

[billswan]

I just removed one injector from my 25/2. That cylinder was lazy on start-up.
So I swung the injector line to the side, and reconnected the injector. I rolled the engine by hand and observed the injection event.
It cracked nicely, but sprayed off center.
I inspected the tip. It has a single hole, not on the center of the cone shaped tip.
The hole sprays a nice cone shaped fog of fuel, offset toward the fuel connection on the injector body.
Is this normal?

Yep, sounds right to me at least that is the way my 10/1 IDI worked.
The spray pattern hits the side of the chamber and that helps break up the fuel spray. Then the burning fuel air mix exits the comet chamber out into the cylinder.

Billswan

[SHIPCHIEF]

Thanks!
I'm just sitting here thinking about that spray direction.
I just machined the COV plug for a VW 1.9L TDI glowplug.
Now I'm thinking the injector sprays toward it?
I'm thinking I should install the injector in the head, then pop it a few times before I install the COV plug. I'd like to know for sure where it squirts. Maybe I'll make a paper target for the comet chamber so I can see where it lands.

[LincTex]

My Metro 6-1 has the hole off to the side as well. You have a normal injector - it doesn't spray perpendicular to the injector body axis.

[SHIPCHIEF]

It turned out to be simpler than I thought.
I just re-installed the injector, and looked into the COV hole.
Sure enough, there was the injector tip at the top, with the nozzle hole in plain sight.
The spray from it must have been directed at the COV valve, so that air blasting out of the chamber would atomize the fuel spray some more while running in the low compression configuration.
In the case of a COV plug, it's probably been a success because the plug runs a bit hotter than the rest of the head, not having any cooling water passages.
I the case of a glow plug, the injector blasts right onto it. No wonder the shortest protrusion, or recessed plug works well. (based on reports from users)
I'm a few projects shy of testing this, I just pulled down the exhaust system. My turbo project has advanced from selecting and rebuilding the turbo, now I need to make the manifolds and oil lines.
Also, I need to run down to the auto parts store and get an exchange starter.