13 replies to this topic

[JackF]

Just taken apart my carb, and bought a rebuild kit from minispares.

The car wasnt running quite right, so decided this could be a start.

I have my dad to help me, along with various Haynes manuals, however i want to impress him with some knowledge.
Has anyone got any tips and tricks rebuilding these, that they could share?



I did find a lot of crap in the bottom, surely this cant help the running of the car.

[jimnali]

Jack
The SUcarb website contains instructions on dismantalling and re-assembling the HS4.
http://www.sucarb.co.uk/technical.aspx

[JackF]

Jack
The SUcarb website contains instructions on dismantalling and re-assembling the HS4.
http://www.sucarb.co.uk/technical.aspx

cheers!

[jimnali]

The rebuild kit includes a replacement spindle and bushes for the throttle butterfly. The spindle is a straightforward replacement but fitting buishes to take up any wera in the carb body requires some engineering expertise and tools. The usual recommendation ius to use a long reamer to remove metal evenly from both sides of the carb. The SUcarb instructions suggests using a lathe to to this. This needs to be done very accuartely so is a job best left to specialists.

Alternatively you can ignore the bushes and simply replace the spindle and this will remove most of the wear. I have done this on my car and it has worked well.

[dklawson]

The rebuild kit includes a replacement spindle and bushes for the throttle butterfly.

Really? I have never seen a carb rebuild kit that contained those parts. I know they are available separately but the kits I have purchased only contain the gaskets, seals, and perhaps a new float valve. Some contain a new jet but not all of them I have seen.

As a footnote to the replacement carb spindles, for some models there are oversized spindle shafts availalbe that are sized to take up the clearance in the carb body without installing bushings. They are a "relatively" inexpensive fix for carbs you cannot afford to have professionally bushed.

Jack, though that carb looks dirty on the outside, it's not too bad. The crud in the bottom of the float bowl should be cleaned out but take a look again and you will notice that the connection point for the flexible jet tube is actually in a little pocket at the bottom of the float bowl. That pocket minimizes the amount of debris that can get into the carb jet. In short, the float bowl looks worse than it really is.

There are numerous documents on the web about converting a Waxstat jet to be "like" a normal solid jet. The process involves removing that crimped on metal cap at the bottom of the jet and replacing the cartridge inside with a couple of pennies, then crimping the cap back on.

Be sure to follow all the steps listed in your Haynes manual and on the SU/Burlen web site linked above. Remember that there are pre-startup settings that must be made to the float level, the metering jet, and the fast idle/choke. It is very easy for people to forget that those pre-start adjustments have to be close to correct or the engine will not re-start. Read a lot before taking your carb apart and take your time putting it back together correctly.

[jimnali]

[Really? I have never seen a carb rebuild kit that contained those parts.

Yes. A service kit contains only the gaskets and needle valves but the rebuild kit includes a new butterfly, spindle and bushes.

If you do want to avoid the waxstat SUCarb sells a replacemen t linkage which allows you to fit a standard jet. This sounds like a better solution than altering the waxstat.

Note that the rebuild kits do not include a new carb needle - you may want to buiy one seperately to complete the restoration.

[dklawson]

Thanks for the additional information on the rebuild vs service kits. Very good to know. I guess all I have ever seen and bought were the service kits.

The Waxstat conversion only costs you a couple of pennies (literally) as opposed to the jet conversion kit. The end result is the same with the exception that you spend a lot more on buying the conversion kit.

The link below is to an old thread on the subject. It includes a text description and pictures of the conversion.
http://www.theminifo...->-non-waxstat/

[JackF]

these? http://www.minispare...its.aspx?130205

[bmcecosse]

If the flutterby has the little valve in it - remove and solder up the hole..... and do eliminate the waxstat either with a new jet or the 2 penny trick.

[JackF]

where should the breather on the carb connect too? Possibly a stupid question

[dklawson]

You will need to clarify that question a bit. The "carb breather"?

There is an upward pointing brass pipe on most HS carbs for connection of the PCV hoses. Is that what you are referring to?

On many HS carb float bowl lids there is often a horizontal brass tube that is an overflow for the float bowl. When that is present you will often see a piece of fuel line attached and that line is just routed down and away from the exhaust system to insure an overflow doesn't land on the exhaust.

[JackF]

Sorry, i should have made myself clearer. Hopefully this picture will help.


I understand the fuel inlet and overflow brass tube coming from the top of the fuel float bowl.

but as seen in this picture there is another brass tube, which has been blanked off (using a small length of tube and a bolt) which comes from the main body of the carb. I believe this is a breather tube, however i may be wrong?

If it is a breather, i think it might go to the crank case?

I have actually rebuilt the carb since this picture, so when I get home i will upload some better, cleaner photos.

Edited by JackF, 18 June 2012 - 12:54 PM.

[dklawson]

The crankcase has breathers. The tube with the length of hose and bolt is a connection for the PCV valve system. The plumbing is a bit different from year to year but basically if you have a Smiths PCV valve, its "bottom" port connects via a hose to the point you are asking about. The other port on the Smiths PCV valve would connect (typically) to either the valve cover or to a crankcase breather.

[JackF]