Su carb q's

[Rustina 510]

I am currently at a stand still, I'm waiting tell after Xmas to buy the rest of the parts I need for my car, in the mean time I would like to clean up and polish my dual 48mm su carbs, I looked on line and in the how to section of the forums and couldn't find alot of info so far.

 

I know their are some Datsun wizards who have a vast amount of exp with these.

 

Any links to a site would be helpful, or just let me know what kind of sanding and polishing wheels and products would work.

 

Thx again guys.

 

E.

[Rustina 510]

And z-therapy is a good tool, but i think he said it costs money just to have them look at them, I think they are in good condition but i havnt opennes them up yet.

[Skib]

same thing goes for polishing any kind of aluminum.

 

 

just dont mess with the insides of the domes, pistons, or bodies. stick to just the outside of them.

[FoxyRoadster]

like skib said, just hit them with any sort of polish compatible with aluminum and should shine up just fine.

 

If you plan on cracking them open I'd suggest getting a basic rebuild kit. You don't have to replace the needle, float, or such but I'd suggest replacing the gaskets.

[Rustina 510]

Thx guys, I'm going to take the cap off and start polishing when I get home, what about the rest of the carb, dremel polishing wheel?

[exit64]

I use a muslin wheel mounted on my drill press. Use Mother's Aluminum Polish and you will be happy with the results. You can get a cheap polishing kit at harbor freight to get started with if you don't have anything. Google how to polish aluminum and follow the directions as it is different than doing stainless as to what compounds to use. Red Rouge will never give you a mirror finish, use tripoli. I have used a dremel and wheel on Mikunis and have gotten very good results. It's a sickness. Once you start it is really hard to stop. :lol:

[Rustina 510]

I totally hear you, i can't wait to get started, I found a web page that uses white rouge instead of red and it looked like a damn mirror.

 

On the web page it totally described how the su carbs work to, and what problems to look for to determine if a rebuild is needed.

 

My wife is going to kill me when she sees me in the dining room taking apart my carbs. Lol

[bonvo]

paging zerow

 

[Dirk Diggler]

If your carbs are fairly clean (no pits, corrosion, build up) Mothers Aluminum Mag Polish will work awesome like mentioned above. A dremel tool will be your best bet to be able to handle it, unless you have a drill press like the other guy said, then mount a polishing bit or wheel to the drill press and leave it stationary and handle the carb with both hands. If your carb has pits or corrosion, fine grade steel wool (#0000) will work great, as well as 1500 grit wet sand paper. The sand paper will leave marks and makes the polishing step take longer, so it should only be used if the steel wool does not help. You can try misting them with a solvent (acetone, gasoline, etc) just be VERY careful with it, and only use it on the outside. We all expect pics when you are done

[DISLEXICDIME]

What size engine you running?

[zerow]

paging zerow

 

Thanks bonvo...

First off... DO NOT MIX UP THE DOMES! Put a small mark on them so you can properly fit them back together later. I have a small "tick" mark on the mounting flange for the dome for proper fitment.

 

I did exactly what everyone else does with aluminum. I started with 220 grit, and sat on the back patio and removed all of the surface inperfections. I worked my way through 240, 320, 400 and 600 grits. Then, I took #0000 steel wool with some Mothers polish and thats where I really started seeing the shine. I bought some polishing compound and used a drill mounted buffing wheel to get the final product as seen here. You will want to screw the domes to a piece of wood or something to keep it stationary, don't put the dome in a vice... :o

 

And one more word of advice...once you're done polishing the domes, you won't be able to stop...the tops of the float bowls will be the next victims...and you will have to use a dremel polishing wheel to get those handled for sure...

[dennis]

use jewelers rouge after you get a decent shine. Make sure you change your wheels when you change your polishing compounds. I always use jewelers rouge to get mirror like shine. As a note, ditch the dremel and get a bench top buffer and save yourself a ton of time. The area you cover with a small dremel tool is just crazy small. You can even get some wheels in tight corners.

 

edit, added more info:

 

Just think of you compounds like sandpaper. Use a coarse compound and work your way down. Jewelers rouge is one of the finest grit compounds.

[exit64]

Rustina,

So do you have specific question about setting these up or just about polishing? After years of messing with Roadsters and SU carbs my advice to you is this. At the very least, spend the money on having Ztherapy put the bearing throttle shafts in the body. If you can afford it, let Steve do the whole job of the rebuild. The two things I always do to the Roadsters for the best driveability is Z therapy carbs and an EI Dizzy. If you can't afford the bearing job then PM me and I can put you in touch with Dan Garrison who can rebush the original throttle shafts. If you have any leaks on the shafts throughout the range you are pissing up a rope. You will get it to run pretty good but never perfect. Go over to the techwiki on www.311s.org and read the SU section. I use the micrometer method to get my starting point and then tune from there. I run ATF in my dash pots as it stays pretty much the same in all temp ranges. I prefer to use a synchrometer over a unisynch as it has a readable scale instead of just a floating ball. They are about $30 on Ebay all day long. The VW guys use them a lot for the downdraft setups that they run.

Post some pic of the polishing job and good luck.

Mike

aka exit64

[Rustina 510]

What size engine you running?

 

A L20b, I have the z hitachi 48mm big carbs

[Rustina 510]

They actually look pretty good inside, float looks nice, needle looks good, all 4 movin parts seem good and the gaskets seem to be in very fair condition.

 

I think I'm going to just polish, bolt up, adjust and tune. And see how they do before I decide to take them to z therapy.

 

I'll def do a before and after pic, and the intake mani should be mail to me today "thx jester".

[skunk]

thats the set up i had on my 510 before i sold it

good thing i got to keep my carbs, they will go on my next datsun or maybe ill toss them on jessis wagon

[skunk]

http://www.youtube.com/watch?v=2a-eojUkrVE&feature=player_embedded

[Rustina 510]

Yeah I'm hoping it all goes together well with little problems

[banzai510(hainz)]

Skunk,, idle shounds High

is that rockerarm noise I hear? try tighten up the lash and see if it quiets it down a bit.

[Rustina 510]

He sold thAt car dude

[skunk]

Skunk,, idle shounds High

is that rockerarm noise I hear? try tighten up the lash and see if it quiets it down a bit.

 

yeah idle was was high, first time geting sus to start, thing wanted to go 25 without me hitting the gas.

alot of the noise is from the 2 inch exhaust hiting