So who has bumped the power on a 6CTA cummins

[70deuce]

EGT and boost gauge tap points. Where are you guys running those gauges from? Any easy ports to unplug and tap in to? I have been checking all pages of this post and maybe missed the one addressing this question. Thanks

 

[dochowz]

Closest to the turbo is ideal

 

[Ford Mechanic]

Hey guys I don't have a pyro yet, so what type of temp from your egt are you getting out of 2 turns out on the rate screw and 2 clicks on both the springs? And this is on the MW pump, Thanks!

 

[panzerwillie]

I think you have nothing to be concern with, i think 2 turns on the rate screw is not enough to build to much heat unless the screw was out some as i have a M925A2 and a M931A2 and the 25 the screw was flush with the nut and it took almost 5 turns to notice a power increase even after working with the no air screw where the M931 had about1i/8 of a inch above the set nut and with 3 turns you can feel a big gain, hope this helps...

 

[Ddmk18]

I turned my screw out 4 turns and out in 4k gov springs in my m931a2. I haven't adjusted the main fuel nuts yet but on a 2 miles 10% grade pulling my 105a3 loaded it never gets above 1275 degrees. That's floored the whole way up the hill.

 

[MtnSnow]

Ddmk18,
What RPM are you hitting with the 4K springs in?

 

[Ddmk18]

I don't push it any harder than about 2700 but it will pull past that.

 

[nevrenufhp]

2700, you got a ways to go. For getting up to speed, 3200. For sustained, 2800.

 

[k5ontherocks]

Can you go more than 4 clicks on the stock gov springs to pull more rpms?

 

[nevrenufhp]

You can, but the idle comes up with it and makes it a little harder to start. Plus, the pedal gets pretty sensitive.

 

[racing4funn]

Main fuel screw on top is a noticeable power increase. One additional problem I'm have is that it strong until right before it shifts and then is nearly stops pulling, takes a few seconds then changes gears and takes off again. How do I power through this instead of the stalling?..

No it wasnt in the manuals.

 

[jwesley74]

Main fuel screw on top is a noticeable power increase. One additional problem I'm have is that it strong until right before it shifts and then is nearly stops pulling, takes a few seconds then changes gears and takes off again. How do I power through this instead of the stalling?..

No it wasnt in the manuals.

The adjustment on top is the low fuel. The adjustment on back under the tin cover is the no air adjustment for smoke. Under that is the full fuel adjustment that bumps the real power. I discovered after several months of adjustments and looking/investigating fuel/power issues on ours the short metal line coming from the intake manifold to the little tin cover on the back of the pump is for the ratio valve. Our metal line at the fitting to the manifold was missing rubber grommet. allowing air blow by. Resulting in the turbo not spooling up when I let off the pedal and applied full pedal again. Installed rubber grommet and now takes off like a rocket every time I step on the pedal.

Now I'm on to another issue. After turning up full fuel idle is at 900 in neutral and 700 in gear. Further problem is even with high idle it stalls when approaching a stop. I have to keep pressure on pedal to keep it running. I haven't taken the time to test & tune it on back roads adjusting the governor down etc... So I'll report back if anything changes after playing with those. When I got the truck the idle was so low it would stall. I turned up governor 3 clicks on each like I read in here and that brought idle up perfect. Then I turned up low fuel 3 revolutions. Again it helped. But still had issues with falling on its face when let off the pedal. That was the rubber grommet problem. Since installing grommet I have turned down low fuel 3 revolutions, turned up full fuel 2 revolutions. Now thinking turning governor back down 2 clicks, test it and see. Might turn up low fuel to help with stalling issue if I can get RPM's down to normal with the governor. Basically its a trial and error. The problems I have encountered with this truck is clear the pump/linkages/adjustments were messed with at the base before being sold. It's just figuring out the right sequence to dial it in right. Besides idle/stalling it runs GREAT! Pulls better than ever. So I'm getting closer.

 

[74M35A2]

Main fuel screw on top is a noticeable power increase. One additional problem I'm have is that it strong until right before it shifts and then is nearly stops pulling, takes a few seconds then changes gears and takes off again. How do I power through this instead of the stalling?..

No it wasnt in the manuals.

What you are feeling is correct. That is the governor pulling out fuel at the governed RPM as it is supposed to. On the 8.3, that is in the range of 2000-2300rpm. To overcome this, buy and install an aftermarket governor spring kit (GSK). This can raise the governor de-fueling up to around 3400rpm or so. You can also adjust the stock springs, but after a few click idle and restart can be affected.

 

[nevrenufhp]

The adjustment on top is the low fuel. The adjustment on back under the tin cover is the no air adjustment for smoke. Under that is the full fuel adjustment that bumps the real power. I discovered after several months of adjustments and looking/investigating fuel/power issues on ours the short metal line coming from the intake manifold to the little tin cover on the back of the pump is for the ratio valve. Our metal line at the fitting to the manifold was missing rubber grommet. allowing air blow by. Resulting in the turbo not spooling up when I let off the pedal and applied full pedal again. Installed rubber grommet and now takes off like a rocket every time I step on the pedal.

Now I'm on to another issue. After turning up full fuel idle is at 900 in neutral and 700 in gear. Further problem is even with high idle it stalls when approaching a stop. I have to keep pressure on pedal to keep it running. I haven't taken the time to test & tune it on back roads adjusting the governor down etc... So I'll report back if anything changes after playing with those. When I got the truck the idle was so low it would stall. I turned up governor 3 clicks on each like I read in here and that brought idle up perfect. Then I turned up low fuel 3 revolutions. Again it helped. But still had issues with falling on its face when let off the pedal. That was the rubber grommet problem. Since installing grommet I have turned down low fuel 3 revolutions, turned up full fuel 2 revolutions. Now thinking turning governor back down 2 clicks, test it and see. Might turn up low fuel to help with stalling issue if I can get RPM's down to normal with the governor. Basically its a trial and error. The problems I have encountered with this truck is clear the pump/linkages/adjustments were messed with at the base before being sold. It's just figuring out the right sequence to dial it in right. Besides idle/stalling it runs GREAT! Pulls better than ever. So I'm getting closer.

Sounds to me like the gov springs are too tight. If that idle spring(biggest one of the gov spring set) is too tight, it cant recover in time to keep it from stalling. It also makes it take some extra cranking to start, unless you push on the pedal a little. Back it off 1 click, and it should be much better.

 

[racing4funn]

What you are feeling is correct. That is the governor pulling out fuel at the governed RPM as it is supposed to. On the 8.3, that is in the range of 2000-2300rpm. To overcome this, buy and install an aftermarket governor spring kit (GSK). This can raise the governor de-fueling up to around 3400rpm or so. You can also adjust the stock springs, but after a few click idle and restart can be affected.

I was going to give it a few clicks anyways but thought I had a problem to cure first.. two clicks here I come. If want more then will get a spring kit

 

[racing4funn]

Is the turning of the governor spring the center of the top where the two(across form each other) slots are and do I turn them clockwise or counter?

 

[nevrenufhp]

Is the turning of the governor spring the center of the top where the two(across form each other) slots are and do I turn them clockwise or counter?

The nut is the slotted part in the middle. Clockwise tightens them, and they only go in quarter turn increments.

 

[PureMayhem]

So what is the stock setting for the fuel screw? How many turns out from fully closed. Just in case someone loses track of how many turns they have.

 

[panzerwillie]

PureMayhem. i have two trucks one a M925 and the other M931, both had the fuel screw set differently the 25 the screw head was flush with the jam nut where the 31 was about of a 1/8 of inch out, this may not be true to all but it was on both of mine, but remember to count the turns out so you know where to set back to if you need to, good luck...

 

[MO MV man]

Yesterday, I did the air filter mod using the WIX 46664, as laid out by acme66 in another thread. Worked GREAT! Ought to flow a lot better than the original Donaldson.
Today, I adjusted my governor springs three clicks.
I used the alternator nut (NO sweat) and accessing the springs is no problem whatsoever. I did have to remove the shutdown lever (again, no problem).
Idle speed did rise to 1000 BUT it's a piece of cake to adjust. No worries whatsoever.

After the engine got some heat in it, I slowly brought the rpm's up and it went to 2500 effortlessly.
I'm beyond impressed.
The throttle is SUPER crisp for such a huge engine. I'm shocked.

I ran out of time to take it for a spin before heading to work this afternoon.
I'm dying to get it out on the road!

What I've done so far:
Air filter mod
Straight pipe
1.75 turns on fuel screw
3 clicks on governor springs

Soon as free time allows:
Pull the fuel screw and grind some off of the bottom to allow more turns (aiming for 3)
Adjust the main fuel on the back of the pump