Idle or governor adjustment after swapping DVs

CTD2500

CTD2500

Brown Between the Cheeks
I swapped my 024 DVs out for 7mm ones to add some fuel on the top end yesterday, (I have a new turbo setup and it was cleaning all smoke at full throttle with the AFC at full travel) but now the truck is much harder to start and has kind of a weak idle.

I bumped the idle speed up, but I wondered what else I could do to help it start better. It was below freezing this morning and it took 30 seconds of cranking to get it started.

Before the swap it started and idled good and strong. The pump is a 160 unit that was rebuilt and maxed/balanced by Seth Farrell in 2015. It already had the 024 DVs in it when he worked on it, so I assume he set it up to work well with them, and it has always started and idled perfectly since then. This is the first time I’ve changed anything in the pump since the rebuild, other than AFC tuning.

I found a thread on DTR where someone mentioned backing off the governor springs one click and then readjusting the idle to fix a weak start/idle, but I didn’t want to mess with that before asking some opinions on here. I could move the preboost screw in a bit too, I guess. Obviously the 7mm DVs move less fuel on the bottom end, which is something I forgot about when I ran them years ago (before the rebuild). It seems like it needs to be adjusted to compensate for that.

What are your thoughts?
 
Yeah, maybe I’ll give him a shout. See what he says.

I tried turning the preboost up before leaving work about an hour ago, and it actually started a lot better. Maybe that’s all it needed? I guess I’ll see what it does tomorrow morning when it’s totally cold again.

I took it out for a spin on the way home, and these 7mm definitely move more fuel on the top end. Boost hit 81 psi, up from 76 with the 024 DVs, and there was a visible smoke trail behind me. It was totally clear before. I’ll probably have to limit AFC travel for now to clean that up.
 
Still a hard start this morning, but a lot better than yesterday. I think I’ll try a bit more preboost, then if it’s still stubborn or if it gets smoky when leaving from a stop I’ll talk to Seth before I do much else.
 
Turning up the preboost screw, isn't gonna change how it cranks, unless your holding down the throttle pedal while starting it.
 
CTD2500 said:
Still a hard start this morning, but a lot better than yesterday. I think I’ll try a bit more preboost, then if it’s still stubborn or if it gets smoky when leaving from a stop I’ll talk to Seth before I do much else.
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If idle is weak youll want to loosen the governor springs to .040-.050" stud protrusion then raise the idle speed back to 8-850 rpm warm in park. If that isn't enough to fix it you can swap a softer idle spring into your pump.

jasonc said:
Turning up the preboost screw, isn't gonna change how it cranks, unless your holding down the throttle pedal while starting it.
Click to expand...

If the afc is set up for full travel and the fulcrum arm has been raised so it doesn't fall under the foot at full travel it will limit cranking fuel if slid back too far/ too low preboost fuel setting.
 
Phooker said:
You mean you don't floor it while you're cranking?
Click to expand...

That's only needed on a 6.0 ford.


The 96 12v truck we had years back (should have kept it) would start noticeably quicker when you would rest your foot on the throttle. Just the slightest bit of throttle and it would fire right off. Without a little throttle it would spin 1-2 revolutions. It was almost a near stock pump.
 
Red Sleeper said:
That's only needed on a 6.0 ford.


The 96 12v truck we had years back (should have kept it) would start noticeably quicker when you would rest your foot on the throttle. Just the slightest bit of throttle and it would fire right off. Without a little throttle it would spin 1-2 revolutions. It was almost a near stock pump.
Click to expand...
The 5k's Darren put in my truck love a good throttle tap on start up.
 
Same with my 4k’s. I’ve adjusted everything. No change. Cranks instantly with a toenail on the pedal.
 
CTDYoungGun said:
If idle is weak youll want to loosen the governor springs to .040-.050" stud protrusion then raise the idle speed back to 8-850 rpm warm in park. If that isn't enough to fix it you can swap a softer idle spring into your pump.
Click to expand...

Ok, I’ll try those adjustments and see what I get. Thanks!
 
I guess I should update this; it’s been about a week since I messed with it and I’ve been busy.
I adjusted the governor through the top with the AFC removed, but I ran into an issue with the battery in my digital mic being dead, so I couldn’t measure stud protrusion. So I just backed it off one click and tried it. I can measure it next time I have the top off to double check.

The idle is much stronger, has that nice bark when you start it up warm—no throttle needed. Idle is about 850 in park, but I didn’t have to adjust it after messing with the governor. I had adjusted it right after installing the 7mm DVs already, so I guess that’s all it needed.
Cold starts are OK, but those are harder to compare to before the DV swap since cold starts aren’t always consistent.

It finally snowed here and they salted the roads, which means this truck is parked until spring. I’ll have to wait til then to try it more, but it seemed pretty good the couple times I drove it after the adjustment.

Thanks
 
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