Hitachi VC42-4A Carburetor Rebuild

[r1lark]

NOTE 1: Edited 1/05/2025 to move some pictures and information to a later post.

NOTE 2: Edited 1/08/2025 to add additional info as to which sealing washers are not included in the rebuild kit that I purchased.

Decided to start a new thread on this carb rebuild, versus posting it as part of my " Rehab of Patrol L60-2-00655" thread in the Projects section (Link: viewtopic.php?t=6242} Hopefully this might help folks in the future. It will be pretty basic, so those well versed in carb rebuilds will be able to skip over most of it. But hopefully for those not well versed in carb rebuilds, this will show them that they can rebuild their own carb -- it's not hard, just go slow and work methodically.

As far as locating a carb kit, I got my carb kit several years ago off eBay, from Australia (thanks to all those down under that make reproduction parts for the Patrol). Here is a current eBay link to that seller: https://www.ebay.com/itm/196473447672?_ ... R6rp0Z3_ZA.

In doing some online searching, there doesn't seem to be any other carb kit sources, at least that I could find. Possibly some of our Australian members can locate some others and provide that information. Here is a pic of my kit:

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As far as disassembly/reassembly instructions, the Patrol shop manual is very vague on that, at least compared to what I'm used to (ie, very complete instructions in the various Studebaker shop manuals, Triumph car shop manual, even the Standard Blue Streak Jiffy Kits). Searched online and the only hits were from this forum. So, I made copies of what was in the original Patrol 60 Engine Manual (the one with the gray cover), as well as a scanned early '60s Owners Manual that is scanned/posted here on 60Patrol. Also copied the exploded diagram from the parts manual and used that to mark what was taken off and in what order. Also am noting the 'as-found adjustments as it is disassembled.

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Nameplate with carb model number:

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Very dirty outside, but that will come off during cleaning:

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Just as a preview, it's pretty dirty inside also, especially the float bowl:

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One concern is there are a lot of various fibre sealing washers on this carb but not many sealing washers provided in the kit. Following is a list of the washers not provided in the kit:

• Bowel drain washer, fibre (10mm ID x 12mm OD x 1mm thick)

• Extra vacuum port plug washer, copper

• Power Valve seat washer, copper

• Seals for sight gauge, rubber

All the sealing washers in the kit are aluminum. In doing research on applicable sealing washers, I found out that the aluminum washers take more torque to seal than a comparable fibre or copper washers. Extra torque on the threads in a 65 year old, hard to find casting is something that concerns me. But don't get me wrong, I'm not knocking this kit, because it otherwise is quite complete, especially the various brass components like jets, bleeds, etc.

A caution on the tools used to disassemble/reassemble the carb. This carb is similar to many others I've done (including on my Studebakers) in that the screw slots are unusually wide. My recommendation is to get some of your old worn out screwdrivers (or some cheap new ones) and grind the ends to fit snugly in the slots. You sure don't want to mess up a part because of an ill-fitting screwdriver.

Actual disassembly starts in the next post.

If anyone has any advice, sources for carb kits, etc please post them here on this thread.

[L60Boerne]

Thank you Paul. I have a few kits in storage. I have these carbs on all but one of my Patrols. Santa's Sleigh has the NAPA knock off of the Rochester B, which works very well too after Eddie made the parts it arrived with missing.

Coyote Patrol, hopefully with some minor help from me, will try to get the Flagstaff Patrol back on the dirt and rocks this year. If it runs as the seller says, then it will get the rebuilt VC 42 sitting on my shelf.

It is going to be a good year.

Rolling and Patrolling,
L60 Boerne

[r1lark]

NOTE 1: Edited 1/05/2025 to add additional pictures and information.


The following is a step-by-step disassembly of the VC42-4A. Do need to note that I'm going by the illustration and item numbers and part numbers shown in the 1965 Nissan Patrol parts catalog. I showed a pic of the illustration in the first post of this thread. Where I use a number (for example, #12), that will reference the item number in the parts manual illustration Figure 10. Also, since the service manual gives essentially no disassembly procedure, the steps shown below are the order I used to disassemble the carb, but are not necessarily the "required" order.

Before starting disassembly, take pictures of the carb from all sides, top, bottom, etc. Take pictures during disassembly also, to guide in reassembly. Don't know about everyone else, but I would not be able to remember every detail of where all the parts went and in what orientation without the pictures. Don't believe this carb has ever been apart before; if yours has been, don't take for granted that it was reassembled correctly! Also, don't throw away ANYTHING until the carb is cleaned and reassembled and it works well.

Different people go about disassembling carbs in different ways. I used to use an old egg carton to put the various parts in, arranged in the order of removal. I've since upgraded to a clear plastic storage box (like a fishing lure box) with removable dividers. It doesn't matter how you do it, but keeping the parts in order has always helped me to maintain the order of reassembly:

Started by removing the fuel inlet banjo fitting #8, and the associated bolt, mesh filter, and two fiber washers. Interestingly, the bolts on this carb seem to be metric. Red arrow shows the banjo fitting before removal; second pic is a different view of the banjo:

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Bolt, banjo inlet fitting, small wire mesh filter, and two fiber sealing rings; arrow shows the mesh filter on the outside of the bolt:

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As a reference, measure and record how much the choke rod #20 protrudes from the choke lever #21, as shown in the following marked up picture; as a reference, mine measured 5/32".:

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Then, remove the screw (red arrow) and slip the choke rod #20 out of the choke lever #21:

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Remove the cotter pin #23 which attaches the lower end of the choke rod #20 to the throttle shaft linkage (shown circled in red in the following picture), and remove the choke rod along with the two washers and the spring:

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Remove the six screws holding the top cover to the main body, and remove the top cover. This provides access to the float; note the gasket shrinkage circled in red which is a good reminder to check the flatness of all the gasket surfaces:

DSC00021.JPG gasket shrinkage.JPG

Checked the float level measurement per the service manual, but the float seemed to be way out of adjustment. Not sure why..................
I could not figure out how to remove the odd shaped retainer (red arrow) that holds the float pin (Nissan calls the float pin a "shaft") in without destroying the retainer, so decided to just remove the whole float assembly made up of the float #9, float shaft #10, and float shaft bearing #11 by removing the two screws (blue arrow shows one screw) that attaches the assembly to the carb cover:

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Here is the 'other side' of the retainer that holds the float shaft. Didn't want to take a chance on ruining it by trying to remove it, and really don't see a reason to remove it. (I have learned over my lifetime about being cautious about tearing up pieces that may not be available new anywhere in the world .)

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Removing the float assembly allows access to the needle and seat assembly #12, consisting of the seat, needle, a spring, and a pin that rides against the float tab:

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Based on the good condition of the choke plate and associated linkages, the plan is to leave the choke plate and linkage in place in the top cover: they will clean up fine in either carb cleaner or a ultrasonic cleaner without disassembling any further.



Turning to to the main carb body, next was to remove the accelerator pump and associated linkage. The accelerator pump #42, and spring #44 are held in with a small cotter pin #43, all these are shown on the left side of the following picture, circled in red:

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Remove the cotter key and remove the accelerator pump/shaft and spring. This carb has an interesting method to actuate the accelerator pump -- there is a shaft #32 and spring #40 actuated by the main throttle plate shaft via a link #55; this shaft extends up thru the main carb body. Unpin the link from the throttle shaft #50 by removing the very small hairpin clip #56 (red arrow is pointing to where the clip is), and remove the shaft and spring:

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Here are all the accelerator pump parts laid out in roughly the correct orientation:

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If you look down the accelerator pump well, you can see the check ball held in by what looks like a brass retainer:

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CAUTION: do not do what I initially did and bend the brass retainer to get the check ball out!!!
If you look at the parts illustration, #45 is the check valve assembly and it comes out of the bottom of the bowl as shown in the following pictures:

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Hopefully the retainer will bend back over the check ball without breaking. Luckily the kit does include a new check valve assembly.

Next, the bowl drain and fibre washer (not shown on the parts illustration) were removed:

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Disassembly will continue in the next post since we have reached what appears to be the maximum 20 pictures per post.

[r1lark]

NOTE 1: Edited 1/10/2025 to add information and pictures related to the removal of the fuel level gauge.

Continuing disassembly..................

Remove plug #17 to access the level gauge #16, and remove the level gauge and the packings (seals) #18 and #19. At least in my carb, the bottom packing was not as thick as the top packing. the top packing is three pieces of rubber stacked together, while the bottom seemed to be only one piece. These are not included in the rebuild kit that I have, so am doing some searching to find a replacement product. Note that the plug #17 was originally staked in, so that will need to be done on reassembly.

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Unfortunately, the marks on the level gauge that are supposed to denote the required level have disappeared on my gague!


Next remove the power valve assembly, shown in the following picture circled in red (yes I know this picture shows the accelerator pump still installed, but I didn't take one with just the power valve assembly):

DSC00028.JPG power valve.JPG

Remove screw #38, and remove the power valve assembly with springs and needle:

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Although it is not shown on the parts illustration, there is still another part of the power valve assembly to be removed -- the seat and its copper washer shown below by the red arrow:

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Here is the seat and copper washer removed:

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Below the seat is the power jet, also not shown on tbe parts illustration; it is shown in the following picture (sorry for the poor picture):

DSC00053.JPG arrow to jet.JPG

Although the power jet is not shown on the parts illustration, it is listed in the parts list, along with a washer. Don't know if this is a fibre or metal washer, but I'm reluctant to try to remove this jet for fear of damaging the washer and/or the threads in the carb body. Would not want to risk soaking the carb body in the caustic carb cleaner if the washer is made out of fibre. An alternative would be to clean the body in the ultrasonic cleaner with a mild detergent like Dawn dishwashing liquid or maybe Simple Green.


Next remove the accelerator pump nozzle #47 (shown just below) by removing the screw #49:

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The following picture shows the nozzle #47, the screw #49, two fibre washers #22, and the mesh filter screen #48:

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Below the nozzle assembly is the spring carrier #46 and check ball #41:

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Remove the spring carrier and turn the body upside down to remove the check ball: Spring carrier and check ball removed, shown with the nozzle assembly:

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Next we will remove three items denoted by the red arrows:

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Remove the slow air bleed #34 (on the right):

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The wire is to differentiate this bleed from the bleed on the left.

Remove the slow jet #35 (in the middle):

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Remove the main air bleed #33 (on the left):

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Next we will remove the main jet carrier and main jet, located here:

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Remove the main jet carrier #29 and the copper washer #30:

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The main jet #31 is screwed into the end of the main jet carrier #29:

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Behind the main jet carrier and main jet is the nozzle set screw #26, the nozzle (emulsion tube) #25, and two packings #27 & 28. This picture looking down the passageway shows the nozzle set screw #26; apologies for the poor picture:

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The nozzle set screw, nozzle, and packings could be removed. However, I made the decision not to remove them for two reasons: 1) according to the limited information I could find, the packings adjust the position of the nozzle, and the positioning of the nozzle is critical to the correct operation of the carburetor, so did not want to risk the nozzle not going back to the correct location, and 2) the makeup/material of these packings is unknown, and they are not included in the rebuild kit (at least, not the kit that I have).


Disassembly will continue in the next post.

[RiverPatrol]

That's a lot of pieces!

[r1lark]

That's a lot of pieces!

For sure River, there are more components in this carb than most I have rebuilt! Thanks for making it a sticky, hopefully it will help some other folks.

[r1lark]

Finishing up with disassembly....................

Remove the throttle valve adjust screw #58 and its associated spring #57:

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Time to remove the throttle body (Nissan calls it a throttle 'chamber') #51 and its associated gasket #52 by removing the four 1/4" bolts #14 and lockwashers #13:

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Remove the vacuum connection and the plug for the second vacuum port; neither of these are shown on the parts illustration:

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Note that there is a thin copper washer (red arrow) under the plug; I tried gently to remove this washer, but could not, so be careful when you clean the throttle body that you don't lose it:

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I did not remove the throttle valve (butterfly) #53 or the throttle shaft #50 and associated linkage. The throttle body and shaft did not have any perceptible wear, so there was no reason to. If yours has wear, this is a bit of machining to make bushings, bore out the throttle body, and fit the bushings properly that most hobbyists are not set up to do. If you have a lot of wear, hopefully it will be on the throttle body bores and not on the shaft. NOS shafts may be unobtanium (unless River has one or two stashed away ). I suppose maybe the shafts could be built up by hardchroming, but that would have to be farmed out as well.


Here are all the parts laid out prior to cleaning. Don't throw away the gaskets, in case you have to refer back to them as far as holes, cutouts, etc:

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Next step is cleaning the parts. For years I used the one gallon cans of Berryman Chem-Dip for cleaning carbs, automatic transmission parts etc. But about a year ago I got am ultrasonic cleaner and absolutely love it. Been using it for cleaning engine parts, carbs, transmission parts, etc. Just be careful what type of cleaner you use, especially on aluminum parts. One odd thing about the ultrasonic cleaner is that it will turn some types of brass parts a dark color it you leave them in too long. The ultrasonic cleaner has been a well used tool for me, but if you are just going to do one carburetor and nothing else, it wouldn't be worth buying one -- just use the Berryman Chem-dip or a similar cleaner.

Here is the ultrasonic cleaner being used, a relatively large Vevor unit that will fit a lot of larger engine parts:

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The really important place to concentrate is ensuring that the small passages in the carb body, cover, and throttle body are clear and blown out with compressed air. Also ensure that the various jes, nozzles, and bleeds are clear and blown out with compressed air.

Here are just a couple of pictures of the major carb parts after being cleaned in the ultrasonic. Cleaning solution was Simple Green and water. Average cleaning time was 40 minutes. Note that the throttle body was originally painted:

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All the small parts were also cleaned in the ultrasonic cleaner, just be carful not to mix up the air bleeds. I did have a close call while cleaning the small parts. I use a glass mason jar to put the small parts in, fill it with the same fluid that's in the ultrasonic cleaner, and then put the glass jar in the ultrasonic cleaner; it works well and prevents losing parts since the basket is not a real fine mesh. Anyway, had put the power valve parts in the mason jar (last of the small parts to be cleaned), but accidently knocked the jar to the floor and glass and parts went everywhere. Found all but the spring pretty quick, and got the glass cleaned up to be able to look for the spring. Looked for probably 40 minutes and couldn't find it. If this was a Studebaker carb, I have plenty of NOS and used parts........but these VC42s don't grow on trees as y'all well know. Finally after starting to move the big stuff under the workbench out of the way, the spring was found thank goodness. Had visions of having to locate another carb just to rob the spring out of.


Next post will deal with checking the gasket surfaces for flatness.

[r1lark]

The VC42 carb is a heavy sturdy casting, unlike similar carbs of the same era that I have worked with. On these other carbs (for example, Stromberg WW and Carter RBS) the top covers warp from overtightening of the cover screws, as well as possibly heat and cool cycles. On these other carbs, sometimes that warpage has been so much that they had to be heated up in an oven and 'persuaded' back flat . So this has me in the habit of always checking the flatness of the gasket sealing surfaces.

To do this, I use a known flat surface (a piece of thick plate glass especially for this purpose) and a piece of 320 grit wet/dry sandpaper and a lubricant (WD-40 or similar):

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Spray WD-40 on the glass (believe it or not it reduces the tendency for the sandpaper to slip around) and on the top of the sandpaper. Place the piece you are checking on the paper holding the gasket surface flat against the paper, slowly move it back and forth. I go diagonally right to left and then left to right for a while, turn the piece 90 degrees. do it again, etc:

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Here is the top cover gasket surface after about 30 seconds of back and forth on the sandpaper; the shiny areas (red arrows) at the bolt holes indicate there is some slight warpage at the extreme corners where the bolts hold the cover down:

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After about 10 minutes of less the cover gasket surface looked like this with only a small area left untouched (red circle):

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A few more minutes and this surface was done. This was done for the sealing surfaces on both the carb cover and the main carb body. Here is the main carb body with the gasket surfaces flattened and cleaned up with brake-clean and compressed air, and bagged to keep it clean. Note you can see the nice gasket surface even thru the plastic bag:

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These pieces, due to the heavy solid castings, had only a tiny tiny bit of warpage. Was very impressed with the castings.


Here are all the pieces cleaned and ready for reassembly once replacements for the fibre, copper, and rubber sealing washers not included in the kit are located. Did a bunch of measuring and searching online and have these on order, hopefully they will work.

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[r1lark]

Well, several steps forward, and a big step backwards,

Good news is that we did locate various gaskets to replace those either not included in the rebuild klit I have, or to use instead of the aluminum seals provided. I'm somewhat concerned about using the aluminum seals in some places; aluminum takes more torque to properly seal versus fibre or copper gaskets. On a carb as hard to find as the VC42, I don't want to risk stripping out the threads on the carb body. I'll go thru what has been found later in the post.

The bad news is that, while testing the gaskets found for the sight glass, I wasn't carful enough to make sure the sight tube was seated correctly at the bottom, and chipped one end of the glass. So, I'm looking for a replacement, and have a thread in the 'Wanted' section of this forum about it: viewtopic.php?t=6637 In a nutshell, if anyone has a parts VC42 carb that has a good sight glass, I sure would be interested in obtaining the sight glass (or the whole parts carb if you want to do it that way). Let me know if you have one.

So these are the collected gaskets:

For the sight glass, I found a chemical resistant Fluorosilicone sealing washer that has the correct dimensions, although it's thicker than the rubber pieces that were used originally. (But tyey do compress significantly more than the rubber seals.) The Fluorosilicone is especially applicable to gasoline and gasohol. Got them from McMaster-Carr, p/n 91367A112, 9mm OD x 4.3mm ID, 25 per pack. Cost was $16.10 for the pack of 25. My plan is to test the seal by filling up the bowl with gasoline once the throttle base and main body & parts are assembled (but before installing the top cover). Here are some pics:

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Sight glass with old rubber seal pieces, and new Fluorosilicone seals:

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Several of the carb pieces had 12mm OD x 8mm ID fibre washers for 8mm metric threads. Found a pretty much exact replacement for these, also at McMaster-Carr, p/n 90449A150, pack of 100; cost was $10.10 for the pack. They are about 5 mils (.005") less thick than the originals. Here are some pics:

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The next pic shows the new 8mm gasket on the bowl plug, fits perfectly:

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Also found fibre gaskets for the fuel inlet fitting (takes two), McMaster-Carr p/n 90449A210, 18mm OD x 12mm ID, for metric 12mm threads, pack of 100. Cost was $5.00 for the pack.They are several mils less on thickness, essentially negligible. Pics show how the fibre gasket fits exactly on the fuel inlet bolt:

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Finally, the copper washer that sealed the power valve seat. A perfect replacement found on Amazon, HEROFFIX 20pcs Metric M6 x 9mm x 1mm Copper Flat Washer Sealing Ring, link here: https://www.amazon.com/dp/B0DHMZ7C9P?re ... asin_title. Cost is $5.99 for the pack of 20 washers. I do plan on annealing the copper washer before installing, since modern copper washers made in China seem to be too hard to seal correctly (especially brake hose washers). Here are some pics:

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[Esteban]

What a fantastic thread! You've taken the time to carefully document every single step of the process. Thanks and congratulations!

Sorry to hear about the sight glass. I'm sure you'll find a way to replace it, hopefully from a donor carb.

Could you please share the main jet diameter #. I'm guessing it's going to be a 135. On a side note, I see that your caution on dealing with these old castings and the threads, you're right. On mine, even though I was working on the carb and specially the main jet rather frequently, one day the threads gave up. A beauty of this carb is that you can change the main jet without dismantling everything. I used to do that, since when making a beach trip I will lower from 9000 ft of altitude to sea level. At the high altitude my main jet was a 125. If you will use that at sea level you develop piston knocking almost all the time, so I will stop midway and swap the jets.