Perkins 4108 injection pump

[Liber]

Hello,

I had my Perkins 4108 injection pump rebuild recently.
The mechanic who took off the pump did not mark the timing position of the pump. When he reinstalled the pump he eye balled it and put it more or less where it was.
Since then the engine runs fine, however it is a little harder to start then before.
Are there any issues I should worry about due to incorrect timing? As mentioned above the engine works fine...
Thank you for your help.
Cheers,
Liber

[model 10]

There is a small cover plate on the pump, the one with the fuel return line on top. Under that cover are the marks you line up to time the pump correctly. Depending on the access it probably takes an hour to adjust.
There are usually a pair of marks on the outside of the pump mounting flange that are very close to the correct timing. If the mechanic used those, the timing is probably fine, just maybe not perfect. If they are not lined up I would get the pump timing adjusted.

[Liber]

Ecos, thank you for the reply. Unfortunately there are no visible timing marks on the engine case. The pump was reinstalled more or less where it was before... However the engine works, just a little harder to start...
Liber

[model 10]

The external mark is no more than a small cold chisel imprint at the outboard pump mounting slot. Could yours be under paint etc?
Does the engine start quickly warm? The Perkins manual mentions micro adjusting the pump timing for peak performance and does not say anything about damage to the engine if you don't. As lazy as I am I might live with it if it doesn't wear out the starter.

[Mike OReilly]

Ecos, I had a similar situation to yours a couple of years ago; rebuilt injector pump, less-than-perfect reinstall. Mine must have been more out of alignment than yours b/c mine resulted in very rough starting, and rough operating.

I knew nothing about these pumps and timing so was relying on my mechanic (I know more now ). He finally remembered the alignment marks, and eventually got us sorted out, but it was clear the timing was critical to good starting AND proper running.

I don’t know how refined the alignment needs to be, but after my experience I would be very careful about getting it as perfect as possible.

[Liber]

Ecos,
The timing mark is visible on the pump casing, but not on the engine casing, l did scratch the paint but could not find it.
Yes, the engine starts just fine when hot, just when it is cold that it is a bit more difficult. When the engine is running I did not notice any difference compared to before.
Thanks,
Liber

[rbk]

If you don’t already have the shop manual I’d download it and print it off, you should be able to adjust the timing yourself and it’s a good thing to know how to do.

[Liber]

Thanks rbk, I do have the shop manual bit I cannot locate the timing mark on the engine side,bit doesn't seem to be there.
Cheers
Liber

[rbk]

Likes ecos said you can also remove the timing cover plate and properly time it, the outside one is a general guide and may not be exactly where it needs to be.

[captain465]

If anyone is in need of a rebuilt and calibrated CAV injection pump for a 4-108, I have one available. Also have a set of 4 rebuilt and calibrated injectors, also for the 4-108.
Make me an reasonable offer for one or all.

[01kiwijohn]

One little trick; On almost all engines; when aligning the marks, rotate the engine, by hand, anti clockwise about a quarter of a turn, and then rotate clockwise until the crankshaft is in the correct position; THEN see if the PUMP marks line up.
That way, you'll take all of the free play, in the timing gear train, out of the equation. In cases like this, it can make all the difference.

[ZULU40]

Could be a long shot but my Westerbeke 40N which is built from 4108 parts. I have a cold start system which vaporises fuel into the intake. Do you have anything like that?

[tailgnner32]

Not always will the timing marks line up on a 4-108, most of the time they wont. The Perkins 4-108 injector pump almost always need a little tweaking.
If your getting a little white smoke out of the exhaust when cranking then you would tweak the pump up, or clockwise about 1/8 of an inch.
Just loosen the three bolts that hold the pump, and with a large set of channel
locks around the mounting flange (base of pump where the blots are) turn
it up about an 1/8 of an inch at a time,tighten your bolts and try to start, you may have to do 2 or 3 times to get it right. I've done this many a times, and
I hope this helps.

[Liber]

Tailgunner32, thank you for the suggestion. The engine runs ok and does not smoke so I guess by miracle the timing is more or less right. In this case I am going to leave it as is....
Cheers,
Liber