That's great Esteban, thank you very much!! The measurements are very helpful. I've probably got the level set a little too low now, but I'll install the carb and see how it runs. In general, the current thought in the old car hobby is that for older vehicles, the float level should be set a little lower than the manufacturer's setting due to the differences in today's gasoline.
We will see when I get the exhaust together and the carb on.
Thanks again Esteban, you are a great resource!
Hitachi VC42-4A Carburetor Rebuild
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Re: Hitachi VC42-4A Carburetor Rebuild
Continuing the VC42 reassembly................
We will install the new needle and seat assembly #12, and the aluminum washer that was included in the kit (original washer was a fiber material). Here are the parts included in the rebuild kit (first picture), and the rebuild kit parts compared to the original parts in the second picture. Note that in the second picture, I do not have the parts in the correct order, refer to the parts manual exploded diagram for the correct order):
Install the seat and washer into the carb top, and tighten. Install the needle, spring, and the "round headed pin". Be careful that you don't accidently turn the carb top upside down without holding the needle assembly in the seat, or they will come out and find the farthest away corners of your shop to hide! The following picture shows the needle, seat, spring, and pin installed:
Next, check the new float chamber gasket #15 against the original gasket to make sure they match. With the top cover upside down, lay the gasket on the top cover, and install the float assembly using the two small brass screws. Here is a picture of the float assembly before removal during disassembly:
When putting the assembly in place, be careful not to dislodge the needle/seat pin and spring. Also be careful with the brass screws, they have a very narrow slot, so make sure you find a small screwdriver that fits well into the slot; If needed, modify one of your screwdrivers to fit........the next person to disassemble the carb will thank you! Following is a picture of the float assembly reinstalled along with the gasket:
Next step is to check the float level. The shop manual calls for a measurement of 20 to 22mm; since the rebuild kit did not include a float level gauge, I made one from some thin cardboard, 20mm on one end and 22mm on the other end: The shop manual instructions for adjusting the float is as follows (slightly paraphrased), as well as the picture that goes along with the instructions:
1) Turn the carb top upside down so the float is on top and the weight of the float is holding the needle closed on the seat. The manual does not state whether the gasket should be in place while setting the float level, but Esteban says it should be in another post on this site, so that is good enough for me!
2) Lift the float with a finger, then gently lower it until the flap-like contact plate of the float just touches the upper end of the needle valve [I took this to mean just barely touching what I called the "round headed pin" that sits on the spring], and hold the float in this position without pressing down on the needle valve spring.
3) With the float in this position, check the distance between the lower surface of the end of the float and the upper surface of the chamber cover. If this distance is from 20mm to 22mm, the float level is correct.
Some comments: note that the shop manual says to check the distance at the end of the float; I took this to mean at the far right side of the float in the picture, but in the middle of the float if you turned the carb top 90 degrees from where it is in the picture. The float has a ridge in it, with the ridge most pronounced at the middle. Upon disassembly, my float setting was right around 13mm; I can't explain why it was so far off what the shop manual says, unless someone in the past had tried to adjust the float (without pulling the retainer and the float shaft #10 so the float could be removed from what Nissan calls the float shaft bearing #11) and bent the float where the contact plate attaches to the float.
When checking my float adjustment as assembled, it was way off the 20-22mm setting - the contact plate was nowhere near touching the "round headed pin":
So, even though I was trying to avoid it, the retainer (not shown on exploded parts diagram) that holds the float shaft #10 in was bent straight at the bottom (2nd picture) to allow the float shaft and float to be removed. Following are two pictures with big red arrows pointing to both sides of the retainer:
Note that the "top" of the retainer is swaged:
Here is the float shaft #10 and retainer removed:
After a couple of iterations, the contact plate on the float was adjusted so it was just touching the "round headed pin" at 21mm. Let me tell you that holding the float at the point where the contact plate is barely touching the "round headed pin" AND trying to measure the float level with the gauge is not easy at all (unless you happen to be blessed with three hands
)!
Since I wanted to check to make sure the sight glass did not leak, I reinstalled the float and the float shaft (without the retainer), and installed the carb top onto the carb body, just barely snugging the six screws (without using the lock washers). Temporarily installed the fuel inlet parts, and found a length of rubber hose that would fit onto the fuel nipple #8. The carb was clamped to a piece of wood, and using a squirt bottle filled the bowl via the hose as shown in the following two pictures:
To mimic the fuel pump pressure, once the fuel stopped flowing into the bowl and the hose filled up with gas, I blew on the end of the hose. On the positive side, the sight glass did not leak, even when left with gas in the float bowl for a long period of time. But as I sort of expected, the fuel level was way off in the sight glass
:
Decided to put the float back to the measurement that was taken during disassembly, as a starting point. The float was adjusted, put back into the carb top, and reinstalled back onto the carb body. The level was much closer to correct, so made one more adjustment (pretty much back to the 13mm where the float setting was recorded on disassembly), and got float float level where I thought it was acceptable:
I had previously marked the sight glass based on a picture of the carb found in a later year Owners Manual on this site. However, based on recent measurements by Esteban on a spare carb, I know what my Sharpie mark was on the sight glass was slightly low. But the general consensus in the old car hobby is that "modern" gas requires a slightly lower flow level then the original carb specs, so I'll try this float level and see how it does. The float level is relatively easy to adjust by simply removing the top cover if it doesn't run well.
So to finish up with the float, reinstall the retainer and bend the "bottom" end back like it was:
That's enough for this post, we are getting close to finishing
. For the one or two of you who have read this far, thank you. As always, comments, corrections, and advice are much appreciated!
We will install the new needle and seat assembly #12, and the aluminum washer that was included in the kit (original washer was a fiber material). Here are the parts included in the rebuild kit (first picture), and the rebuild kit parts compared to the original parts in the second picture. Note that in the second picture, I do not have the parts in the correct order, refer to the parts manual exploded diagram for the correct order):
Install the seat and washer into the carb top, and tighten. Install the needle, spring, and the "round headed pin". Be careful that you don't accidently turn the carb top upside down without holding the needle assembly in the seat, or they will come out and find the farthest away corners of your shop to hide! The following picture shows the needle, seat, spring, and pin installed:
Next, check the new float chamber gasket #15 against the original gasket to make sure they match. With the top cover upside down, lay the gasket on the top cover, and install the float assembly using the two small brass screws. Here is a picture of the float assembly before removal during disassembly:
When putting the assembly in place, be careful not to dislodge the needle/seat pin and spring. Also be careful with the brass screws, they have a very narrow slot, so make sure you find a small screwdriver that fits well into the slot; If needed, modify one of your screwdrivers to fit........the next person to disassemble the carb will thank you! Following is a picture of the float assembly reinstalled along with the gasket:
Next step is to check the float level. The shop manual calls for a measurement of 20 to 22mm; since the rebuild kit did not include a float level gauge, I made one from some thin cardboard, 20mm on one end and 22mm on the other end: The shop manual instructions for adjusting the float is as follows (slightly paraphrased), as well as the picture that goes along with the instructions:
1) Turn the carb top upside down so the float is on top and the weight of the float is holding the needle closed on the seat. The manual does not state whether the gasket should be in place while setting the float level, but Esteban says it should be in another post on this site, so that is good enough for me!
2) Lift the float with a finger, then gently lower it until the flap-like contact plate of the float just touches the upper end of the needle valve [I took this to mean just barely touching what I called the "round headed pin" that sits on the spring], and hold the float in this position without pressing down on the needle valve spring.
3) With the float in this position, check the distance between the lower surface of the end of the float and the upper surface of the chamber cover. If this distance is from 20mm to 22mm, the float level is correct.
Some comments: note that the shop manual says to check the distance at the end of the float; I took this to mean at the far right side of the float in the picture, but in the middle of the float if you turned the carb top 90 degrees from where it is in the picture. The float has a ridge in it, with the ridge most pronounced at the middle. Upon disassembly, my float setting was right around 13mm; I can't explain why it was so far off what the shop manual says, unless someone in the past had tried to adjust the float (without pulling the retainer and the float shaft #10 so the float could be removed from what Nissan calls the float shaft bearing #11) and bent the float where the contact plate attaches to the float.
When checking my float adjustment as assembled, it was way off the 20-22mm setting - the contact plate was nowhere near touching the "round headed pin":
So, even though I was trying to avoid it, the retainer (not shown on exploded parts diagram) that holds the float shaft #10 in was bent straight at the bottom (2nd picture) to allow the float shaft and float to be removed. Following are two pictures with big red arrows pointing to both sides of the retainer:
Note that the "top" of the retainer is swaged:
Here is the float shaft #10 and retainer removed:
After a couple of iterations, the contact plate on the float was adjusted so it was just touching the "round headed pin" at 21mm. Let me tell you that holding the float at the point where the contact plate is barely touching the "round headed pin" AND trying to measure the float level with the gauge is not easy at all (unless you happen to be blessed with three hands
)!Since I wanted to check to make sure the sight glass did not leak, I reinstalled the float and the float shaft (without the retainer), and installed the carb top onto the carb body, just barely snugging the six screws (without using the lock washers). Temporarily installed the fuel inlet parts, and found a length of rubber hose that would fit onto the fuel nipple #8. The carb was clamped to a piece of wood, and using a squirt bottle filled the bowl via the hose as shown in the following two pictures:
To mimic the fuel pump pressure, once the fuel stopped flowing into the bowl and the hose filled up with gas, I blew on the end of the hose. On the positive side, the sight glass did not leak, even when left with gas in the float bowl for a long period of time. But as I sort of expected, the fuel level was way off in the sight glass
:
Decided to put the float back to the measurement that was taken during disassembly, as a starting point. The float was adjusted, put back into the carb top, and reinstalled back onto the carb body. The level was much closer to correct, so made one more adjustment (pretty much back to the 13mm where the float setting was recorded on disassembly), and got float float level where I thought it was acceptable:
I had previously marked the sight glass based on a picture of the carb found in a later year Owners Manual on this site. However, based on recent measurements by Esteban on a spare carb, I know what my Sharpie mark was on the sight glass was slightly low. But the general consensus in the old car hobby is that "modern" gas requires a slightly lower flow level then the original carb specs, so I'll try this float level and see how it does. The float level is relatively easy to adjust by simply removing the top cover if it doesn't run well.
So to finish up with the float, reinstall the retainer and bend the "bottom" end back like it was:
That's enough for this post, we are getting close to finishing
. For the one or two of you who have read this far, thank you. As always, comments, corrections, and advice are much appreciated!You do not have the required permissions to view the files attached to this post.
Paul
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Re: Hitachi VC42-4A Carburetor Rebuild
Nice job! and you helped me too. I had totally forgotten that I sent a float to Then and Now for rehab.
I can't waitit o see how smooth your runs. That sight glass is way to good! You need an old dirty patina dripped one like all minbe.
Rolling and Patrolling,
David
I can't waitit o see how smooth your runs. That sight glass is way to good! You need an old dirty patina dripped one like all minbe.
Rolling and Patrolling,
David
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Re: Hitachi VC42-4A Carburetor Rebuild
Absolutely amazing! The detail and quality of your pictures are absolutely the best. So easy to follow all the steps.
This is the best guide that I've seen of any topic. Congratulations!
This is the best guide that I've seen of any topic. Congratulations!
Owner of the same Patrol since 1967