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Tips

Bit the bullet......

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William

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and pulled the carbs off the B. I suspect that's the easy part (heck, took me and Dad about forty five minutes, including labeling all the hoses going in and out and taking pics before they came off). Any sage advice on rebuilding SUs?
-William (do we have a jittery smiley?)
 
And, Dad just got back from the parts store, having bought some carburetor cleaner. A big bucket of the stuff, with its own cleaning basket, and a stern warning not to go near the stuff with anything made of rubber
shocked.gif
I wanna go return the stuff for a spray can of something else....
-Wm.
 
That stuff your dad bought is excellent for cleaning carburators but you have to make sure you only put the metal parts in it. Even the spray stuff can eat gaskits. Get carb kits before you attempt it and replace all the gaskits. Follow the instructions very closely.
 
And make sure you open the carb cleaner far away from your house (or at least where you eat). And wear gloves and avoid any skin contact. It's nasty stuff but works great. A 15minute soke will clean all the gunk off. I'm probably going to have to do the same thing with my dual SU's and will be keeping an eye on this post for any tips as well.
 
Hello William,

S.U. carburettors are quite easy to work on.
I suggest stripping one at a time so as not to mix up the same part from the two.
As suggested, get the parts you need before hand. These come in kits and vary from a simple seal kit to a rebuild kit depending on what you need to do.
When you remove the piston from the housing (the main domed part) do not be tempted to use metal polish or any other abrasive on the piston or the internal surface of the housing. Be careful also not to damage or bend the needle. Check that the needle shoulder is flush with the base of the piston. There is no real need to remove the needle unless you wish to check what needle you have. This information is stamped on the shank.

It is essential to centre the jet to the needle when re-assembling the carburettor. This is done by replacing the jet and leaving the securing nut slack, screw the adjusting nut fully up, this leaves the jet top flush with the carburettor choke bridge. Replace the piston\damper assembly (oil the piston centre guide rod first) and tighten down the housing screws. Remove the damper from the piston housing and then using something like a phillips screwdriver push down on the piston and tighten the jet clamping nut. The needle is being used to centralise the jet and once tightened should be correct. Screw the adjusting nut down two full turns (12 flats), this is the basic mixture setting. This setting should be pretty close to giving the correct mixture. To check, put your finger in the mouth of the carburettor and lift the piston an inch or so and release. It should drop back down smoothly and stop with a distinct click.
After installing the units back on the car, you need to synchronise the air flow to each carburettor. If you have a meter, use that if not a piece of small bore hose held to the mouth will get you pretty close. Start the engine and adjust the idle screws until the tickover is about 700 rpm and the air flow is equal in both units, then tighten the throttle shaft between the two. Check this by opening the throttle smarlty and watch the pistons, they should rise and fall together pretty much.

S.U.'s, once set up, do not need frequent tuning or adjusting so if the car doesn't seem to be running too well check things like ignition etc first, don't automatically blame the carburettors.
good luck.

Alec
cheers.gif


[ 03-07-2004: Message edited by: piman ]</p>
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by MickeyMouseMG:
And wear gloves and avoid any skin contact.<hr></blockquote>

i wore gloves when i rebuilt my carb and the stuff ate right through my gloves. the only thing that was left was the part that went around my wrists. theey were rubber gloves imagine that
 
Piman,

You say DO NOT use metal polish or other abrasive on the piston, I rebuilt the ZS's on 79 TR7 last summer and the Haynes manual instructed just the oposite. Obviously I DID use the stuff and it worked great. I did have to make sure that all surfaces were completely free of any left over abrasive prior to assembly. I'm curious as to your thoughts on this.

Steve
 
Steve, the ZS carbs use a rubber diaphragm instead of the aluminum piston and chamber of the SU's. If you use any abrasives on the SU carbs, you take the chance of increasing the clearance between the piston and the suction chamber to the point where there is enough bypass so the pistons no longer function correctly.
Jeff
 
Thanks for the advice, kids! We already got the rebuild kit for two carbs, as well as the doohickey that lets you balance them once reinstalled. One of them may be coming apart tonight. I'm not too too concerned with getting them back together again- I did the Stromberg on my old Midget, and since SUs work on a vaguely similar principle, I sorta know what's inside the things. More than anything-and I'm not kidding here- I'm scared to death of that **** carb cleaner Dad bought. I was expecting some of the spray on stuff and a little work with an old toothbrush to clean them up, but not some mystery solvent that might eat my hands off. I'm certainly not going to open that stuff in the house, or even the garage. I'm tempted to go return it if theyll let me and just use gas from the snowblower like I did with the Stromberg. I mean, how do you get any residue of this cleaner off the parts once they've been dipped? Better yet, since the gallon bucket is way more than we need, what the heck do I do with the leftovers?
-Wm.
 
William,

Another method to balancing the carbs without the doohickey is to take a piece of 1/4" vacuum hose about 3' long, with the engine running, jamb one end in your ear, and the other end down the throat of the carb and listen to the hiss, when they both hiss the same, they are balanced. as for the remainder of the carb cleaner, you can either put the top back on and save it till your next project, or leave the top off and let it evaporate.
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by William:
Thanks for the advice, kids! We already got the rebuild kit for two carbs, as well as the doohickey that lets you balance them once reinstalled. One of them may be coming apart tonight. I'm not too too concerned with getting them back together again- I did the Stromberg on my old Midget, and since SUs work on a vaguely similar principle, I sorta know what's inside the things. More than anything-and I'm not kidding here- I'm scared to death of that **** carb cleaner Dad bought. I was expecting some of the spray on stuff and a little work with an old toothbrush to clean them up, but not some mystery solvent that might eat my hands off. I'm certainly not going to open that stuff in the house, or even the garage. I'm tempted to go return it if theyll let me and just use gas from the snowblower like I did with the Stromberg. I mean, how do you get any residue of this cleaner off the parts once they've been dipped? Better yet, since the gallon bucket is way more than we need, what the heck do I do with the leftovers?
-Wm.<hr></blockquote>

Look at the label on the spray stuff. It will probably tell you not to get it on the gaskets either.
Bob
 
Don't be afraid of it. It's the same stuff that comes in a spray can. Slight exposure isn't gonna hurt you. Now if you wanted to take a bath in the stuff, then there might be a problem. Just put a few of the parts in the basket, submerge them completly for 10-15 minutes, pull em out. Then I lay them on a rag and rinse them off with water. Then go over em with a shop rag. Trust me you'll like the results and easier to use than the spray and scrub IMO. I did 4 Suzuki carbs this way and they cam out great; except that now I have this third eye growing out of my thumb now. J/K!
 
You know, how in cartoons, any sort of poison is in a black container with a gigantic skull and crossbones on it? So's this stuff. I'll probably just go outside in the driveway to clean this stuff. Still haven't figured out what to do with the leftovers. I thought methylene chloride is flammable, and certainly smelly and bad for you, so it can't stay in the house or the garage once the seal's been broken (that was the advantage of the spray can stuff-ease of use and disposal). Sorry to obsess over this, but proper storage and disposal of cleaning supplies is something I've had to learn a little about for work (we have a cafe in the store, so there are strict health and safety rules for leaving things as seemingly innocuous as Windex lying about). Double apologies to Basil, as I forgot my manners and used a swear word that I can get away with at a different forum.
-William
 
Aloha William,

An additional item to check after you cleaned up the carbs is the throttle shaft and the bushing on the carb body that it rides in. Over time the brass bushings and shaft wear from round to oval. This creates an air leak. It will be difficult and mostlikely impossible to set a proper idle RPM. There are specialty shops that will install new bushings and a shaft that will make the carb good as new. SU carbs do an excellant job and as Alec has said, once set up properly, they do not require much attention.

Safety Fast,
Dave
 
William,
another way to deal with reaming to oversize is to borrow my reamer. I'm in Oak Park so give me a call or e-mail whenever you want. My phone number's in the club newsletter.
Safety Fast, Wade
 
Thanks for the replies, gang! The bushings for the throttle shaft are in good shape (did the spray test), as they'd been rebuilt by the P.O. Problem was, all the gaskets and rubber bits were going south, and the needle and jet were wearing a bit as well. Plus, they were simply dirty, and a good cleaning certainly can't hurt. One of them is in bits now, pending a dip in the cleaner.
-Wm.
 
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