High altitude compensator 1HZ retrofit? (1 Viewer)

[janyyc]

Subscribed! Did you have by any chance the part number for the HAC? Please share your set up too this looks like a very good option

Yours should have it already installed on your HZJ78.

@JDM Journeys - I’m looking forward to following the installation!

 

[Rigster]

Not sure if this is still available, but here is one for sale on mud:

For Sale - [SoCal] - 1HZ High Altitude Compensator - Bellows

High Altitude Compensator for a 1HZ. was removed to add a boost comp with turbo. $75 plus shipping

forum.ih8mud.com

I personally just left mine in there, and have not adjusted anything(besides timing) because it is all working great as it is. I have not messed with the fuel screw or the altitude compensator in any way. Max boost I am currently running is around 17.5 but daily driving without revving the engine right up and it typically boosts around 12--14 (2-3000rpm)

 

[Blomdala]

Well, I was able to source an HAC from a member on here, and its on its way from the US as we speak. I'll source a gasket for the cover before I attempt any disassembly. Then I'll see if it makes any difference. This truck lives at 1100m (3600 feet) and regularly sees climbs to 5000 feet in the summer.
View attachment 3134094View attachment 3134094

Looks good! I think if you see smoke while driving, it will definitely help. I live at 5300 and installed it at like 200 where I used to live and it’s nice and clean exhaust all the time. And quite responsive.

 

[himhj60]

This is 60 with HAC, if you want ,I will find 80 HAC as well.

 

[JDM Journeys]

Not sure if this is still available, but here is one for sale on mud:

For Sale - [SoCal] - 1HZ High Altitude Compensator - Bellows

High Altitude Compensator for a 1HZ. was removed to add a boost comp with turbo. $75 plus shipping

forum.ih8mud.com

I personally just left mine in there, and have not adjusted anything(besides timing) because it is all working great as it is. I have not messed with the fuel screw or the altitude compensator in any way. Max boost I am currently running is around 17.5 but daily driving without revving the engine right up and it typically boosts around 12--14 (2-3000rpm)

That's the one I bought. Kraig was great to deal with, and its currently winding its way north...
Now Darren. You "have not messed with the fuel screw or the altitude compensator in any way" BUT you put in a turbo, you great dirty cheat. LOL. Tsk tsk. 17.5 psi, eh? Is that all? (Yes, jealousy is terrible to witness.)

 

[mt72]

Yours should have it already installed on your HZJ78.

@JDM Journeys - I’m looking forward to following the installation!

I am keeping the engine rebuild for the end with a turbo set up

 

[JDM Journeys]

I've received my HAC from a very nice fellow by the name of @BreckenridgeCruiser and it looks great! Thanks buddy!

Now, the snag. I sort of suspected this, but having it in hand seems to confirm that the fuel "Nozzle Pipe" that bolts onto the horizontal top of the OEM pump cover is oriented vertically or sideways on my new to me HAC cover. And a quick check of partsouq confirms two different nozzles. It doesn't say which matches which, but it's safe to assume (if it's EVER safe to assume) that the alternate one fits the HAC model.

Here's mine:

This pic shows it upside down orientation, so in situ the overflow faces down, and rubber lines go on the other two barbs.

Here's what I assume is the HAC version:

Slightly different orientation of the pipes. So something to keep in mind if you are doing this retrofit in the future.

I haven't attempted to fit anything yet, but I'm guessing my existing pipe work is not going to allow it to work from the side of the new cover? So I've just this minute placed an order for the new pipe. Sigh. Once I get my seal kit, and my new pipe work, I'll revisit and attempt to fit the new cover. Unless I've missed something else, which is entirely possible (likely?). I'll update when the parts arrive.

 

[Blomdala]

I've received my HAC from a very nice fellow by the name of @BreckenridgeCruiser and it looks great! Thanks buddy!

Now, the snag. I sort of suspected this, but having it in hand seems to confirm that the fuel "Nozzle Pipe" that bolts onto the horizontal top of the OEM pump cover is oriented vertically or sideways on my new to me HAC cover. And a quick check of partsouq confirms two different nozzles. It doesn't say which matches which, but it's safe to assume (if it's EVER safe to assume) that the alternate one fits the HAC model.

Here's mine:
View attachment 3139296
This pic shows it upside down orientation, so in situ the overflow faces down, and rubber lines go on the other two barbs.

Here's what I assume is the HAC version:
View attachment 3139297

Slightly different orientation of the pipes. So something to keep in mind if you are doing this retrofit in the future.

I haven't attempted to fit anything yet, but I'm guessing my existing pipe work is not going to allow it to work from the side of the new cover? So I've just this minute placed an order for the new pipe. Sigh. Once I get my seal kit, and my new pipe work, I'll revisit and attempt to fit the new cover. Unless I've missed something else, which is entirely possible (likely?). I'll update when the parts arrive.

You are on it, if you see in my thread I attempted to bend my tube (others had success with it ) but I cracked mine so I ordered the other style since partsouq had pics. I then just got longer hoses to make it all work fine.

 

[JDM Journeys]

You are on it, if you see in my thread I attempted to bend my tube (others had success with it ) but I cracked mine so I ordered the other style since partsouq had pics. I then just got longer hoses to make it all work fine.

Good to know I'm on the right track. Thanks for the confirmation. So.. my existing hoses won't work either? I didn't catch two different versions of those on the diagrams.

 

[Blomdala]

Good to know I'm on the right track. Thanks for the confirmation. So.. my existing hoses won't work either? I didn't catch two different versions of those on the diagrams.

Looks like I didn’t take a pic before lol. I just went and got a pic of mine. I just extended one line because I didn’t want to bend anything and fuel line is cheap!

 

[JDM Journeys]

Looks like I didn’t take a pic before lol. I just went and got a pic of mine. I just extended one line because I didn’t want to bend anything and fuel line is cheap! View attachment 3139367View attachment 3139368

Thanks so much! That's extremely helpful!

 

[BreckenridgeCruiser]

@JDM Journeys Glad it found a new home!

Here are some pictures of the nozzle that came with that hac (I reused with my boost compensator as there were no issues with fitment).

 

[JDM Journeys]

Thanks to all who have contributed here. The last of my parts came on Friday, so yesterday it was time to dive in. I had a complete seal kit (for bosch ve pumps), a new fuel pipe assy, and of course the compensator itself.

I should preface by saying I did this all in situ. Its doable, but awkward at times.

First things first. Remove the old cap. The FSM shows so-so detail, but in essence, you need to remove the four perimeter bolts (5mm allen key I think), and also the a/c vacuum idle up thingy on the side (three more bolts). Pulling the forward battery and the throttle linkage is also a good idea for access. And of course the two fuel hoses have to be detached.

At this point you can lift the cover partway off, but don't get carried away. Once you've lifted one edge, detach the spring from under the cover. The details of this spring are in the service manual, but the other end has another spring and a pin, so be careful. Lots of small parts to go flying.

Okay, the cover can come off now, and you can dive into the bag of washers, orings and seals.
I replaced the main cover seal, as well as the oring on the throttle control shaft once I removed it from the old cover (required light tapping to get it out, with soft hammer). Also fitted new copper washers either side of the fuel pipe, and a new washer behind the fuel screw. I counted the turns on the fuel screw as I removed it, so I could get it back in approximately the same spot.

I mistakenly thought that the idle and max speed limit screws would go back in the same place but as the pic above shows (where I have them in wrong) the covers differ in their castings in that area, so I had to reinstall both screws after the fact. I was worried about the hoses not being the right length so I clocked the new fuel pipe until it seemed to work with both, although the smaller diameter hose up top was a trifle long (that's a good problem). Here's the orientation that seemed to work:

I did notice a little dirt in the banjo bolt so I picked and sprayed it out thoroughly before reinstall.
Then it was time for reinstall. I had removed the throttle control plate before removing the cover, but this would have been better done on the bench for both removal and reinstall, methinks?

At this point, you have to somehow get the spring reattached to the linkage, clear the intake with your new taller stack, and get the bolts back in, while overcoming the resistance of the springy linkage pushing up on the underside. Not easy.

 

[JDM Journeys]

Ultimately, you end up with these parts left on the bench...

And your IP now has a chimney!

I started it up, and was happy to see no leaks, so a good start.
First test drive seems to have a little more pep and a little less egt-dictated throttle-off on hills, but that may be placebo effect? More testing required...

 

[JDM Journeys]

Just a couple of points for previous posters in this thread...
First off, I did absolutely nothing, tuning wise, after installing the new (to me) HAC stack. I reused my fuel screw (with a new washer and o-ring), put it in (approximately) the same number of threads as it was in my original IP cover, and reused the stock springs. I did replace the oring on the shaft connected to throttle, since i reused that original assembly with the new HAC. I also installed, as shown above, new copper washers, a new fuel manifold, and a new cover to pump gasket.

I can't speak to improvements yet, but I can say that it starts and drives at least equal to the way it did before, with zero adjusting, beyond what may have inadvertently gotten changed in my switchover. Hope this helps anyone else considering this swap. Driving in the days to come will hopefully yield improvements at altitude.

 

[Jalfa]

Just a couple of points for previous posters in this thread...
First off, I did absolutely nothing, tuning wise, after installing the new (to me) HAC stack. I reused my fuel screw (with a new washer and o-ring), put it in (approximately) the same number of threads as it was in my original IP cover, and reused the stock springs. I did replace the oring on the shaft connected to throttle, since i reused that original assembly with the new HAC. I also installed, as shown above, new copper washers, a new fuel manifold, and a new cover to pump gasket.

I can't speak to improvements yet, but I can say that it starts and drives at least equal to the way it did before, with zero adjusting, beyond what may have inadvertently gotten changed in my switchover. Hope this helps anyone else considering this swap. Driving in the days to come will hopefully yield improvements at altitude.

Thanks for this info. I'm considering the same upgrade to my 1HZ.

Have enough miles passed for you to judge if it's a worthwhile upgrade?

 

[JDM Journeys]

Thanks for this info. I'm considering the same upgrade to my 1HZ.

Have enough miles passed for you to judge if it's a worthwhile upgrade?

I've driven it to work a few times this week, but it was extremely cold (like -30°c) so hard to judge changes at those temps. I do think the fuel screw may be in a bit further than it was in the other cover - seem to get a little more black smoke in 2nd under acceleration. So more adjusting is needed. My plan is to pull the (non-op) ACSD soon, get the timing back closer to spec, then turn the fuel back a tiny bit more. Then I should have a better idea of how it works... Esp if I go into the mountains.
The one problem - the very day after I installed the HAC I found a deal on a 1hd factory CT26 turbo, and have been gathering bits ever since. So this may end up getting pulled again in favor of a boost compensator.

 

[Jalfa]

I've driven it to work a few times this week, but it was extremely cold (like -30°c) so hard to judge changes at those temps. I donthimk the fuel screw may be in a bit further than it was in the other cover - seem to get a little more black smoke in 2nd under acceleration. So more adjusting is needed. My plan is to pull the (non-op) ACSD soon, get the timing back closer to spec, then turn the fuel back a tiny bit more. Then I should have a better idea of how it works... Esp if I go into the mountains.
The one problem - the very day after I installed the HAC I found a deal on a 1hd factory CT26 turbo, and have been gathering bits ever since. So this may end up getting pulled again in favor of a boost compensator.

Nice, turbo is another solution!

 

[JDM Journeys]

I've changed my mind about three times since this thread was first created. First I found turbo bits. Then I found another truck that I was orginally going to go with instead (newer hzj77). Ultimately, I decided to stick with Olbetsy and am back to fiddling with the IP. Yesterday I reinstalled the previously pulled ACSD, after cleaning it up, and did some more linkage adjusting etc. Hopefully I'll be able to speak to HAC improvements better, as temps are back to zero-ish celsius.

I should add that the HAC cover uses different bolts (actually studs) to adjust idle speed etc. I reused my originals but they aren't ideal.

 

[Old Dirty Beard]

I've changed my mind about three times since this thread was first created. First I found turbo bits. Then I found another truck that I was orginally going to go with instead (newer hzj77). Ultimately, I decided to stick with Olbetsy and am back to fiddling with the IP. Yesterday I reinstalled the previously pulled ACSD, after cleaning it up, and did some more linkage adjusting etc. Hopefully I'll be able to speak to HAC improvements better, as temps are back to zero-ish celsius.

I should add that the HAC cover uses different bolts (actually studs) to adjust idle speed etc. I reused my originals but they aren't ideal.

Any life left in this HAC testing thread? Wondering if it is worth the energy.