Datsun Roadster Forum-311s.org

Matt, I performed major cleaning of my carbs during my rebuild, but when I got it back together one was not sliding freely, so I just removed the dome and slide and gave it all a good spraying out with carb cleaner and it feed up nicely.

That has been one heck of a journey! Time to fully enjoy.

Quite a different look than 2013! You should feel proud of your work. Now you get to experience the flip side of a build. Driving is equally as enjoying.

So I know driving it will not be enjoyable, but since it’s winter I was thinking of taking the carbs off to clean them. I’m not going to lie. I’m a little intimidated by the carbs because it’s something I don’t know about. I’ve watched some videos and read a little bit. Any advice on which posts to read or WIKI would be greatly appreciated.

My plan - Take plenty of picture.

pull the fuse to the fuel pump and run the gas out of the carb bowls.

Disconnect all the cable and linkages

Take the float bowl tops off and pull out with the long drain tubes attached (is it a good idea to reroute the overflows somewhere else? I remember reading about possible fire due to their dump out locations)

Unbolt the carbs and remove.

Do I drain the oil by just tipping it over and pouring out of the dash pot? Do I catch what comes out to measure how much?

Take the piston covers off and remove the piston and the needle.

Suggestions on how to clean? Just use carb cleaner or anything else? A guy on YouTube used “Gibbs” and scrubbed with steel wool? Thoughts?

Clean the float chamber.

Remove and clean the jet screw and choke assembly.

What time of oil to use?

Thanks

Lots of threads on oil type. I have used Marvel Mystery oil
Be sure to use or cut out a new gasket for fuel bowls to avoid a vacuum leak
overflow tubes can be replaced with rubber etc, emake sure they are LONG and go down away from manifold
Fuel valves can be gummed up or bad inside so good to check them
Banjo screen should be checked replaced as they can deteriorate
Do not use any steel wool, pistons are tolerance matched to domes, don’t mix up. A soft toothbrush works with carb cleaner.
Check nozzle holes for enlargement or ovaling. You can buy the pin size, .092? to check.
Check needles for wear and straightness.
Tighten domes down evenly so the pistons move easily up and down.
Replacement correct screws are avail from Zippy67 and his business(vendor). Very nice.
I like the ADQ needles as researched by Keith
Throttle bushings wear can be a source of problems and it is beyond most people to repair.
Finally, if you can get ahold of the Z Therapy CD which details carb rebuilding and maintainence it has EVERYTHING about the carbs and shows all that they do to rebuild a carb set which is why their rebuilt carbs are so nice.
Set up is important too and that is detailed in the WIKI
Good luck!
Linda

These carbs are pretty simple and should not be intimidating. I would check to make sure you don't have big leaks at the throttle shafts while it still runs, squirt some starter fluid or carb cleaner at the shafts when running and listen for leaks or changes in RPM. IF there are leaks, you may want to send them to professionals.
1) Don't do both at the same time! One at a time only, so that you do not mix parts - this is pretty important.
2) There is only about a tablespoon of oil in the dashpots, not much to worry about and no need to measure.
3) 20 Wt. Oil is but one of many suggested oils, 3-N-1, Marvel Mystery Oil, Motorcycle shock absorber oil and more have been suggested.
4) I have used regular carb cleaner in the past. But don't use on plastic or rubber parts (Power nozzle for instance.)
5) Don't overtighten or lose the float cover screws, they are unusual and difficult to source!
6) There are things that take more expertise including checking for leaking throttle shafts, out of round/bent needles, and worn (oblong hole) power nozzle. The needles and power nozzle can be replaced, but the leaking shafts require more involved fixes.

Hope that helps some, there are plenty of threads here, and instructions in the wiki to help in more detail.
Linda posted while I was writing, so a lot of the same things here.

Notoptoy - that helps quite a bit and was exactly what I was looking for. I was thinking of Z therapy carbs and if I have the leaks you speak of I’ll do that. Thanks.

The Z therapy carbs are great, but cleaning yours will still show improvement.
Guage pin I got on Amazon to check nozzle size on 1600:
Z therapy carbs:
Linda

Took the car for a late cruise up and down the road again. Checked the carbs for any vacuum leaks around the throttle shafts and there was no change. So I’ll try to give them a good cleaning before I replace.

Linda, is there a write up somewhere on how to use the gauge pin? Don’t know what that’s for.

Matt,
You just drop the guage pin into the nozzle hole and it should fit nicely, telling you that the hole is not oversized, wallowed out, or oblong.
Keith, the carb guy, used to loan out pins so you could check. The U20 uses a different nozzle size from the 1600.
But since you can buy the guage pin yourself, for $2, no problem.
See Tech Wiki write up towards the bottom where Keith documents pin size:
http://www.311s.org/pmwiki-311/pmwiki.p ... sNewSuTech
Also, if your nozzles are worn, per the Z Therapy CD , they can refurbish them with an insert that is precisely the right size. So check their website. Then you don’t have to buy the whole nozzle.
Linda

Linda wrote: ↑Sun Dec 08, 2019 9:29 pm Matt,
You just drop the guage pin into the nozzle hole and it should fit nicely, telling you that the hole is not oversized, wallowed out, or oblong.
Keith, the carb guy, used to loan out pins so you could check. The U20 uses a different nozzle size from the 1600.
But since you can buy the guage pin yourself, for $2, no problem.
See Tech Wiki write up towards the bottom where Keith documents pin size:
http://www.311s.org/pmwiki-311/pmwiki.p ... sNewSuTech
Also, if your nozzles are worn, per the Z Therapy CD , they can refurbish them with an insert that is precisely the right size. So check their website. Then you don’t have to buy the whole nozzle.
Linda

Thanks

One of the things on my todo list.

The car sits, sags, and/ or is a little soft in the rear suspension when someone’s in it. Is there anything to add to the rear suspension to stiffen it up? Like an additional leaf? I have plenty of extra leaf packs I could steal a leaf out of to add to mine. I took my dad for a ride yesterday and both our fat butts in the car squatted it out quite a bit. I know I’m being picky, but I love where it sits with no one in it, but want it to look the same height when I’m in it. I also don’t want to raise it up so it doesn’t look high in the rear when I’m out of it. I can live with 1/4” to 1/2” extra height but no more. Any ideas?

You could add a JCWhitney style helper spring? Might make the ride a little bouncy but should not affect the resting ride height much.

You could also find a shop to re-arch the original leaf springs.

Shocks? I did the KYBs but now the Bilsteins are the premium choice.

Linda