Cummins 6CTA8.3 Injection Timing

WillWagner

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That sounds right and makes sense, but I don't know for sure if this will accomplish what you want. I do know that if a vehicle comes in with a hard start, white smoke complaint, after checking some other stuff, verifying the engine to pump timing is done. I have seen pump timing off just enough that when the engine is pinned and the pump timing tang is not centered, either way, just enough for the pin to not seat all the way, cause issues like hard start , low rpm, slow acel/stumbling on acceleration and white smoke. But, timing the engine, popping the gear off and backing the engine is a 20 minute deal. It will be harder to figure out the 8°. Your head gasket will be fine! Try it and see what happens, it is easy to reset if it doesn't do what you want it to.

And just an fyi, the MW was one of the most finicky inline pumps Cummins used. They were primarily used on things like school buses and garbage trucks. ReCon would re-man them and they would most always be hard to start or make white smoke. We got to the point that we would not use ReCon...they are a Cummins subsidiary...we would use a local ADS shop. The pumps that were done by recon were often taken to the local shop to see what was wrong. Sometimes only 1/2 degree off in timing caused issues, but that is internal pump timing, not engine to pump, two different things.
 
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4XDesign

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nevrenufhp

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Wish I could Help this is to new for me please please please do a bad ass wright up and tons of pics :beer:
That's what I offered earlier in the thread. I find it easier to do the method described by 74M35, than to use the spill port method. I timed my 12Valve Dodge this way a few years back, and it took 3 tries to get it in the sweet spot. I started a little high, then backed it off, then forward a couple degrees. Test N Tune is a good way to dial in your setup, since there's no magical number of degrees that works for every setup.
 

fattboy123456

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That's what I offered earlier in the thread. I find it easier to do the method described by 74M35, than to use the spill port method. I timed my 12Valve Dodge this way a few years back, and it took 3 tries to get it in the sweet spot. I started a little high, then backed it off, then forward a couple degrees. Test N Tune is a good way to dial in your setup, since there's no magical number of degrees that works for every setup.
I still have no clue how to do it :-(
 

nevrenufhp

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We(you and me) are going to do the timing. Not just you winging it alone. Marysville isn't all that far from me
 
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74M35A2

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Start here: https://m.youtube.com/watch?v=gwepAWiP_m0

This method will get you to the data tag spec of 8 degrees. From there, degree out the crank damper with reference from TDC to 10 degrees to BTDC, in single increments. Timing tape will have to be based upon crank damper diameter. The damper measures 246mm diameter, so a full 360 degree timing tape would be 246mm x 3.14 = 772.44mm. From there, you can mark one degree every (772.44mm/360 degrees) = 2.15mm. Every 10 degrees would be 21.5mm. If you are targeting 16 degrees, then you would really only need to do a single measurement of 8 degrees BTDC, which would be backed up 17.3mm from TDC. TDC can be any point on the damper where you can affix a nice pointer once the cam gear pin can be engaged.

Once locked in at TDC, pull the tach adapter and cover, and pop the IP gear loose. Then back the crank up to 8 degrees BTDC, and lock the IP gear back down after cleaning tapered mating surfaces with brake cleaner. Torque to spec, check Cummins Quickserve (free online service manual specific to your engine serial number) to obtain that value.

https://quickserve.cummins.com/info/index.html

That should give you 16 degrees of injection timing. I am picking the 16 degrees based off of the RV group opinions, decide which value works for you. There is head gasket risk of going more, supposedly.

I'm going slow with this, as I want to install and record EGT's before I do anything.

CORRECTION: The damper is listed as 246mm diameter, which is 9.685".
 
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nevrenufhp

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I have watched that video i must be retarted
It's low tech, and very basic once you see how it's done. This is my basic idea of what happens, minus a couple fine details.
-Pull out the timing pin in the pump.
-Line up the timing marks so you can put in the pin, but dont put in the pin.
-break loose the nut on the end of the pump.
-Make sure the marks are lined up again, and pin the pump.
-I use a harmonic balancer puller to pull the gear loose.
-Now it's time to back the engine up to advance it. Easy way is to use a socket on the alternator, while watching the pointer/measurement as described earlier.
-Tighten up the pump gear pretty tight, but not full torque.
-Pull back out the timing pin.
-Fully torque the pump nut.
-Assemble all the little pieces, and it's done.
 

74M35A2

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Yes, but remember the pump, as long as it is original to the engine, already has the data tag timing built into it when it is pinned. So once you find and set TDC on the balancer, remember, you already have 8 degrees of injection advance at that point. You'd only back it up an additional 8 degrees if your target was 16 BTDC. Also, be sure to spray brake cleaner into the tapers of the pump shaft and pump gear while they are apart. Any oil in there and it will slip.

I'm not sure a harmonic balancer puller will fit in the opening. May have to cut it down somewhat and re-machine it or just make your own puller cross bar.

I would also recommend marking the pump gear and shaft with permanent felt tip once set to indicate slippage, if the gear is fastened with a nut where you can see the shaft (I believe so).

That is not me or my video. I have no idea who that cat is. The purpose of that was to demonstrate the pump pin and verbal description of the engine timing pin to locate #1 TDC.
 
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fattboy123456

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It's low tech, and very basic once you see how it's done. This is my basic idea of what happens, minus a couple fine details.
-Pull out the timing pin in the pump.
-Line up the timing marks so you can put in the pin, but dont put in the pin.
-break loose the nut on the end of the pump.
-Make sure the marks are lined up again, and pin the pump.
-I use a harmonic balancer puller to pull the gear loose.
-Now it's time to back the engine up to advance it. Easy way is to use a socket on the alternator, while watching the pointer/measurement as described earlier.
-Tighten up the pump gear pretty tight, but not full torque.
-Pull back out the timing pin.
-Fully torque the pump nut.
-Assemble all the little pieces, and it's done.
Thank you now i dont feel totally lost
 

74M35A2

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Here is the timing tape for the balancer. Print this out and adhere to the balancer after you have #1 TDC set via the timing gear push pin. I recommend to then set this scale and your pointer to a non-zero whole number on this scale, such as the 3cm mark. Starting it from 0cm doesn't give the best reference.

http://printable-ruler.net/wp-content/uploads/2015/08/ruler-12in-30cm-USLetter-transparent.pdf

The major tick marks are cm, the minor are mm. Be sure to confirm the accuracy of this scale before you use it (printer sizing, etc..). Compare it carefully to a known reference such as a "real" 12" ruler/scale.

Confirm your balancer OD is 246mm, and then backing up the timing 17.3mm will give you 16 degrees of advance vs the 8 stock (confirm via your data tag). Chose your own advancement amount, this is just the recommendation of the RV group. There are +/- effects of moving the timing.

Also make sure you know which way the engine rotates, sketch an arrow on the damper in permanent marker just to make sure as you setup the scale. You don't want to do all of this only to be setting your timing at 0 degrees and come back saying how terrible it runs.
 
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74M35A2

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Let us know how it goes. If your head gasket shoots out your engine, then maybe my math was wrong.
 

nevrenufhp

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Yes, exactly. The head bolts make a distinct sound as they pop thru the hood.
I mean the cackle (clatter) as you hit the pedal from idle.
 
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74M35A2

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You are all correct. I have not performed this yet. My wife's father died unexpectedly, so I will not have any updates until Christmas break. Lots to sort, named executor of the will, her family is fighting and grabbing things, the usual mess....ugh.
 
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