I am rebuilding an engine and i need to fix the timing. The engine doesn't have a chain or belt, just a gear on the crankshaft and another one on the camshaft.

The camshaft gear has a mark but the crankshaft one doesn't. The only thing the manual specifies is when should each valve open/close. How am i supposed to do this?

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  • Generally there is an index mark on the gears that indicates their position when the crankshaft is at 0 degrees TDC on cylinder #1. Perhaps if you provided some details like make, model, year, and engine model more details could be provided.
    – jwh20
    Commented Aug 23, 2021 at 12:09
  • @jwh20 It is a Ducati Marine DM184HD single cylinder diesel engine.
    – Hristos
    Commented Aug 23, 2021 at 12:14
  • Not exactly a mainstream engine. You might ask around at a shop that services these. I'm sure it's not complicated but it is critical to get it right.
    – jwh20
    Commented Aug 23, 2021 at 12:20
  • There is no "shop that services these"to ask. Shouldn't i be able to find which of the 27 "teeth" on the crankshaft gear is correct by checking which valve is open when or something?
    – Hristos
    Commented Aug 23, 2021 at 12:24
  • @HandyHowie of what part exactly?
    – Hristos
    Commented Aug 23, 2021 at 12:32

2 Answers 2


First step is to get number 1 piston at TDC.

Once you have done that then you can engage the camshaft gear with the crank gear using that mark and looking at the camshaft so that you have it in the correct position or at least close to ie where both valves are closed.

Sometimes you need to turn the camshaft so that as the gear teeth engage the cam gets rotated to the final correct position. This is the case with helical teeth.

  • What do you mean with "Using that mark"?
    – Hristos
    Commented Aug 23, 2021 at 12:37
  • @Hristos your words: “the camshaft gear has a mark…”
    – Solar Mike
    Commented Aug 23, 2021 at 13:03
  • Tried searching marine/ boat engine sites using your Ducati model that can answer questions like yours? You're asking a boat engine question on an automotive site. My brief random reading of marine engines covers many old engines discontinued but still in service with forums addressing similar questions. Answers are usually from experienced boaters and marine mechanics sharing free info.
    – F Dryer
    Commented Aug 23, 2021 at 23:48
  • @F Dryer i am asking a general timing question on a motor vehicle site. The fact that this engine was used on a boat makes no diffirence...
    – Hristos
    Commented Aug 24, 2021 at 11:34
  • @FDryer - Yes, this question is on-topic, though is a little weak on specifics. If you have questions, please see The Help Center in the on-topic section which states, "... internal combustion engines, even in applications other than automotive so long as the question is related to engine or engine accessories." Commented Aug 24, 2021 at 15:33

On my engine, there was a mark on the camshaft gear and an arrow on the crankcase/engine shell. I had to align these while the crankshaft was at TDC. I also found out that the best way to do what i initially asked for is to get the crankshaft to TDC and the camshaft in the midpoint of the valve overlap.

  • Reads just like my answer that I gave you yesterday.
    – Solar Mike
    Commented Aug 24, 2021 at 22:19
  • @Solar Mike You said something that was a bit unclear so if you meant that i'm sorry but what i understood was quite different than what i said
    – Hristos
    Commented Aug 24, 2021 at 22:29
  • Well if you can’t understand what you said then there is little hope.
    – Solar Mike
    Commented Aug 24, 2021 at 22:41

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