Humvee Injection Pump Timing

[jake20]

Quick question / thread hopefully, has anyone seen timing this far to the right side (retarded) on a 6.5L NA engine? Working on a friend’s truck and the timing marks are just super far off to the right compared to what I’ve been led to believe is normal. The truck is a 2001 M1123, compared to my 2004 M1043A2

That being said - his truck with this old pump and timing setting is considerably quieter than mine (very slightly advanced timing to the left). By quieter I mean it really doesn’t clack at all and you can more easily hold a conversation in it.

Lastly - is there a detriment to have the timing retarded like this? Only 2 reasons I’m aware of are:

- Less power
- Harder to start in cold

Thanks everyone

 

[Maxjeep1]

I think it’s too far advanced. I only have my experience with my ip. Might be ok there. This is mine

 

[Retiredwarhorses]

Advanced is towards the drivers side, retarded towards pass side..l
retarded timing will be quieter , advanced will be louder especially on cold start..
the starting point is dead center…and frankly, is where all trucks are direct from the factory.

 

[Maxjeep1]

Advanced is towards the drivers side, retarded towards pass side..l
retarded timing will be quieter , advanced will be louder especially on cold start..
the starting point is dead center…and frankly, is where all trucks are direct from the factory.

I was looking at his picture upside down from mine. His is retarded more than mine…

 

[jake20]

Hm, alright thanks for confirming! Contemplating if I want to retard the timing on my truck now or just leave it haha

With the extra few degrees of the cold advance as well it sounds like a jackhammer on a cold start

My only fear would be accidentally tearing the gasket, because we all know what that means.

 

[jake20]

I was looking at his picture upside down from mine. His is retarded more than mine…

Funny thing is, there’s a proper procedure for civvie trucks that have the electric pump (DS4 I think). I believe the proper term is TDC Offset. But here I am going off of noise levels, assumptions, and well wishes

 

[jake20]

For what it's worth for anyone that comes across this, I retarded my timing to be on the passenger side of the mark, rather than the driver side. I can say that the truck definitely does not clack as much after changing it. It's still there but I'm fine with what it's like at this point. Turning the pump to change the timing whilst having all the injection lines and jazz connected sure is a pain. Overall pretty easy besides the hard to reach 12-point nuts holding it in place.

 

[TOBASH]

For what it's worth for anyone that comes across this, I retarded my timing to be on the passenger side of the mark, rather than the driver side. I can say that the truck definitely does not clack as much after changing it. It's still there but I'm fine with what it's like at this point. Turning the pump to change the timing whilst having all the injection lines and jazz connected sure is a pain. Overall pretty easy besides the hard to reach 12-point nuts holding it in place.

How much power did you lose?

 

[Retiredwarhorses]

Why would you retard the timing? Just set it dead on with the scribe mark and move on.

 

[jake20]

How much power did you lose?

To be honest I can't really attest to losing much at all, at least from what I can notice. Still gets up to speed plenty fast when stepping on it. I only moved it from just left of the mark to just right of the mark. Still pretty close to the center for what it's worth.

 

[jake20]

Why would you retard the timing? Just set it dead on with the scribe mark and move on.

Part of it was for experimental purposes, the other part of it was to try to shut it up a little and see what kind of difference changing the timing actually makes.

The other truck I was working on had it retarded waaaay back when we first got it, several mm to the passenger side, and that thing ran much quieter compared to mine. Figured I'd do some experimentation on mine lol

 

[Thumper580]

Why would you retard the timing? Just set it dead on with the scribe mark and move on.

Warhorse... I've posted that my truck is about 1/4" retarded and I was a bit concerned. I bought the tools to loosen the bolts and move the IP. I moved to to line up the marks.... Started it and it ran like crap and sounded like someone was banging on the side of a steel dumpster with a hammer. Blowing black crap out of the exhaust pipe...... I moved it back to the original 1/4" retarded position. I still think it's not "normal", but it sounds and runs good and the exhaust isn't blowing trash out..... Who knows??? Geez.

 

[Retiredwarhorses]

Warhorse... I've posted that my truck is about 1/4" retarded and I was a bit concerned. I bought the tools to loosen the bolts and move the IP. I moved to to line up the marks.... Started it and it ran like crap and sounded like someone was banging on the side of a steel dumpster with a hammer. Blowing black crap out of the exhaust pipe...... I moved it back to the original 1/4" retarded position. I still think it's not "normal", but it sounds and runs good and the exhaust isn't blowing trash out..... Who knows??? Geez.

Could be a rebuilt pump, advancing the timing will make the motor louder, especially when cold…
A pump every week or so gets replaced, I only use new pumps or TACOM approved rebuilds and I set dead center on scribe and never look back.

 

[Thumper580]

Could be a rebuilt pump, advancing the timing will make the motor louder, especially when cold…
A pump every week or so gets replaced, I only use new pumps or TACOM approved rebuilds and I set dead center on scribe and never look back.

Do you have a source for the TACOM rebuilt DB2831-5149? Thanks.

 

[Retiredwarhorses]

MAC and HPG

 

[jake20]

Yep got mine from Mac as well per RWHs recommendation, no issues thus far and looked new out of the box.

 

[Maxjeep1]

I got mine from HPG. RWH was very helpful but a little secretive about his sources. Lol I don’t blame him at all because nobody wants to tell you about his favorite fishing spot. I got my new IP for 1,500 it was back ordered but everywhere else was 600 to 800 more. I have more time than I got money.