The Official 1HD-T/FT Fuel Pump Mod Tuning Thread (1 Viewer)

[pathfinder_88]

At the risk of sounding somewhat retarded in relation to the knowledge of some the other mudders posting, I'm wondering the best way to go about making some tweaks on my 81. Currently, off the line performance is a bit anemic in 1st gear (5 speed) with 315's. Throw a trailer into the mix and it's almost dangerous turning in front off traffic until boost builds. Note the truck has gauges, 3" exhaust and fuel rod already however I think ATEB tuned it very conservatively seeing as it is challenging on any hill to hit 1200F preturbo. So, my understanding is that I should increase off boost fuel to help spool up to get going quicker off the line? As my egt's are low and I essentially have zero smoke, I am thinking more maximum fuel as well? I'm running 16-17lbs of boost currently on a rebuilt c26. Are there any better pics out there which depict these adjustments so I don't fiddle with the wrong setting?? Thanks guys.

 

[pathfinder_88]

I turned the max fuel screw in a 3/4 turn and it's made an improvement...with some extra egt's of course. I still need to fiddle with the off boost fuel.

 

[TheBigBoy]

The fuel screw will help the spool up. What you want to do is add fuel in certain area's and remove excess fuel in others, which is why its so hard to tune a mechanical pump. And why the initial set up is so important. There is alot in it and far too much to explain, which is the reason not alot of people comment.

 

[gbentink]

G not talking about the diaphram (but yes stronger spring there too),I'm talking about instead of putting a 13mm plunger and dist.head for more fuel ,to just grind(polish)the plate that drives the plunger to essentially lengthen the throw to put more fuel through,and by saying the limit to injecters is limited unless you upgrade ,I'm assuming you mean just changing the breaking pressure for more fuel?

Ahhh ok.

No need to grind, simply select a different plate - there are heaps.

larger than 12mm plungers have proved a real pain here in Oz. Good for drag racing, but not reliable for a daily.

1HDFT has a more aggressive cam plate than 1HDT, but not neccesarliy better

 

[Squash]

Look at page 2.
Good pictures of aneroid pins.
Posts 21 and 29 to start with show profile and on 29 you can see where your fuel pin has ridden the aneroid.

If you want to change settings mark the original spots first, I use front of engine as my ref. just because it happens to line up with the fuel pin and the 17mm nut housing the pin and spring.
Note: this may have to be removed to reinstall aneroid pin

Now the aneroid has a profile and this profile can be changed by rotating the attached diaphram.
Post 29 shows wear marks...where the fuel pin rides the aneroid profile, with this in mind you can change the profile and change where the fuel pin starts and stops by adjusting the spring via the star wheel.

My last adjustment was longest aneroid ramp to front of engine and raising spring pressure by unscrewing star wheel, this should change where the fuel pin rides.

Once started the task becomes virtually self guided:
Remove Boost hose
Remove 4 hex bolts two short on left two longer on right.
Feel spring pressure on cover this can be adjusted by star wheel and/or 12mm lock nut and cam under cover.

Now you decide to either pull the aneroid or turn the diaphram
If you pull the aneroid look down to the star wheel, this can be hand adjusted.

Small puff of smoke to start, pretty clean driving??? and another puff when into passing gear till turbo catches up.

Sounds complicated but is easy

 

[wrongway around]

G ,wow didn't know that. I tried all the top secret cnc grinders in town. Looking to get a 1 1/2 to 2 mil deeper.what do you think? Got a link for a good source ? Us Canadians or so behind on the land cruiser stuff.

 

[FJRanger]

G ,wow didn't know that. I tried all the top secret cnc grinders in town. Looking to get a 1 1/2 to 2 mil deeper.what do you think? Got a link for a good source ? Us Canadians or so behind on the land cruiser stuff.

And we're even further behind....

 

[ForealBoreal]

Graeme,

Any details on spring tensions?

Ps found this goodie on LCOOL

 

[77cruiser77]

Looking at that makes me want to get a four jaw chuck for my lathe. Interesting find there

 

[Tapage]

Ps found this goodie on LCOOL

this it's a work of art that I doubt can be accomplish by my hands ..

 

[TheBigBoy]

It's still a low boost grind/pin.

 

[ForealBoreal]

What's a high boost pin look like?

Say 15-20lb one
And above that?

 

[TheBigBoy]

It curves the oppossite way. As the spring tension preload increases it travels less for the same (say 5psi) increments. So it will need to gradually go deeper and deeper into the pin in a shorter and shorter distance (curved). It will also require a much larger flat area in the deepest part of the grind (full pin throw) to make sure the body of the side pins depth isnt inhibited.

 

[ForealBoreal]

Much like this I am assuming:

 

[TheBigBoy]

Yep. That's a high boosting pin. See the flat area to allow for the pin body. And how's its giving full throw of the side pin (2mm of meat left),

 

[Tapage]

that's a sweet pin ... group buy ..?

 

[hybric4x4diesel]

it look good on that pin, but the camplate can only move 2mm of stroke and any deeper cut on the anroid pin does not serve any perpose for more fuel.so tuning for no intercooler and those with intercooler is completely different ball game.and they is always many way to tune for power depending where you are using the truck for and i pretty sure they is no one setting for all best application the way i see it.

 

[TheBigBoy]

True. But mostly this is what can be easily done to tune without stripping the pump. And why the start possition is so important.

 

[finderscuba]

Would it be possible for a 1HDT guru to create a flowchart type tuning instruction that includes procedures in the correct order, and also takes into account whether an intercooler is present, the fuel rod has been changed, the turbo has been upgraded, higher boost, etc? The steps should be essentially the same, but the actual adjustments may be different based on the above differences. But the overall goals are the same - more power throughout, quick turbo spool, max EGTs, no black smoke.

All the information about max load fuel screw, off boost fuel adjustment, etc is out there, but none of it is included in an all-encompassing tuning guide. I, for one, would pay for such a guide if it existed and was comprehensive.

For the record, I have a ground fuel rod, no intercooler, 3" exhaust, stock turbo @ 15psi.

 

[Dan_J-spec_fj62]

Would it be possible for a 1HDT guru to create a flowchart type tuning instruction that includes procedures in the correct order, and also takes into account whether an intercooler is present, the fuel rod has been changed, the turbo has been upgraded, higher boost, etc? The steps should be essentially the same, but the actual adjustments may be different based on the above differences. But the overall goals are the same - more power throughout, quick turbo spool, max EGTs, no black smoke.

All the information about max load fuel screw, off boost fuel adjustment, etc is out there, but none of it is included in an all-encompassing tuning guide. I, for one, would pay for such a guide if it existed and was comprehensive.

For the record, I have a ground fuel rod, no intercooler, 3" exhaust, stock turbo @ 15psi.

I would second the willingness to pay for such a guide. I am new to the 1HDT and am still base-lining the truck... I has an intercooler and probably an upgraded turbo, but I have no idea what the previous owner did tuning wise. Some bits look a little hack... down pipe is 2.5" then into a 3" exhaust... I just want to get back to a good starting point, then move on to one of the Gturbos...

Dan