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post #118 of Old 03-20-2013 Thread Starter
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Re: Perkins 4.108M DIY Rebuild -- A Narrative

Guilty as charged -- I've been working and failing to share with the rest of the class.

Here are a few more gratuitous gearhead porn shots:

All is not well, however -- I'm now a bit mystified...

I remounted the timing gears to the camshaft, the fuel drive hub, and the idler gear -- making double certain that I got all the appropriate marks aligned.

I then got the injector pump back on, again making sure I lined up the timing marks

Now according to the manual, all should be good to go.

However, being an inquisitive sort I decided to take a look-see at the static timing marks on the injector pump quill shaft.

I expected to see was this...

What I found instead was this...

That "A" line indicates when the pump injects fuel into #1 cylinder on the compression stroke. On this engine, it should happen at 18* BTDC.

Even though the pump and drive gear both can be adjusted to compensate for a little error, this is way beyond that fiddle factor. After monkeying around with it, as best as I can tell, fuel was being injected at about 45* BTDC. That would probably explain why I was getting a little soot on the stern and may partially account for some of that gunk I found in the cylinders.

My suspicion is that when I had the injector pump rebuilt just after I bought the boat, they misaligned the head on the quill shaft (at least that's my hope -- I'll find out when I take the pump in to have it checked out.)

Anyway, this kind of puts me in a holding pattern until I solve the puzzle.

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