3

I am in the middle of replacing my 1998 Dodge Dakota 39. V6's timing set.

According to the manual and everywhere online, the camshaft sprocket dot should be at the bottom and the crankshaft sprocket dot should be at the top.

When I turn the engine to line up the existing sprockets in that configuration, the distributor is firing cylinder 4. If I rotate to where the distributor is firing cylinder 1, then the dots don't line up.

Did the last guy turn my distributor shaft 180 or am I misunderstanding these alignments?

If it is something wonky the last guy did, should I "fix" it? My truck has been running rough, but not terrible. I have a bad cat so I assumed that was why.

Improve this question
2
  • Well, my gut says its more likely you misunderstand than for it to be backwards. My vote is to check the timing with a scanner.
    – David Winslow
    Jul 25, 2015 at 23:00
  • @DavidWinslow I'm certain I have no idea what I'm doing! It seems highly unlikely to me that the engine would run relatively fine if something this major was wrong. Unfortunately, I don't have access to a scanner.
    – Zach Mierzejewski
    Jul 25, 2015 at 23:49

1 Answer 1

Reset to default
1

As @DaveWinslow was suggesting, I think you are misunderstanding things about ignition timing.

The firing order on your Dakota 3.9 should be 1-6-5-4-3-2. The engine is a 4-stroke (or 4-cycle) engine (Suck; Squeeze; Bang; Blow). When cylinder #1 fires, the crank shaft has to go 720° (two rotations of the crank shaft) before it fires again. This means the #1 piston is at Top Dead Center (TDC) twice for every single time it fires. At the same time #1 is at TDC, so is the #4 piston. When piston #1 is on its compression stroke (just at the time of firing), #4 is at the top of it's exhaust stroke. The opposite holds true as well. When #4 is firing, #1 is at the top of its exhaust stroke.

Your engine is not 180° out ... if you've described everything accurately, it's right where it needs to be.

Improve this answer
4
  • Ok, I trust your judgement and my ability to be dumb, but I went and double checked anyways. I rotated the crank 5 times and there were only two events: marks line up, distributor at 4; cam mark 180 "wrong", distributor at 1. Let me ask a stupid question, is TDC for timing chain replacement between the "squeeze" and "bang" strokes?
    – Zach Mierzejewski
    Jul 25, 2015 at 23:43
  • Also, I'm going to install the new set exactly like the old set, I'm just trying to clear up my own misunderstandings.
    – Zach Mierzejewski
    Jul 25, 2015 at 23:44
  • Doing exactly like the old one should leave you just peachie. If it was running before you pulled it apart, this will not be an issue. TDC is between the Squeeze (compression) and the Bang (power) strokes. It is also between the Blow (exhaust) and Suck (intake) strokes as well. This is true for every piston ... remember: 4-cycle; 2 crankshaft revolutions; piston goes up/down twice.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jul 25, 2015 at 23:47
  • I think I get it. I was trying to match the marks against a particular TDC, but they are just supposed to match on one of the two TDC's (for this particular situation.)
    – Zach Mierzejewski
    Jul 25, 2015 at 23:54

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .