23 replies to this topic

[newenglandmini]

I'm reassembling my HS4. In which direction does the throttle plate relief valve spring face - downstream (towards the manifold) or upstream (toward the air cleaner)?  (I presume upstream, because the relief valve should open with engine suction in the downstream direction).

 

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[carbon]

Yes, valve should be positioned to open with engine suction.

 

You may need to keep it to comply with emissions regulations. If not then you're better fitting a butterfly without this valve as it does not do the airflow any favours...

[newenglandmini]

As I was commencing my rebuild I had the same thought.  My car is emissions exempt.  I'll add the plain valve to my next Minispares order.

Thank you.

[dklawson]

Corey, you can remove the butterfly you have, un-solder the existing valve, and solder the holes left behind closed.  Remove any solder high-spots by dragging the butterfly across a piece of wet/dry paper resting on top of a sheet of glass.  All that you need after that is to carefully re-use the oval head butterfly screws (with a bit of Loctite) or use new screws.  New butterflies cost more than you would expect (see part WZX1324, typically around 9 GBP + S&H).  MM only sells the complete kit (shaft and butterfly) for $30.

[newenglandmini]

Doug, you read my mind!  I decided to try that about an hour ago, and I decided to check this post before heading to the shop to give it a try.

[dklawson]

Truth be told, with a big plumbing soldering iron you can do the conversion without removing the butterfly from the carb.  After all... how much drag and flow restriction can a tiny bit of solder sticking above the surface do when compared to that jumbo valve assembly?

[newenglandmini]

Job done.  I agree re: the soldering, but it came out nice and neat by sanding the soldered area.

 

Another question:  I've just installed the needle into the piston as shown below.  I've tightened the set screw and I note that the needle is not rigid.  Is this correct and does this make the assembly self-centering?  I've done old HS2's which require needle centering and I assumed this carb would require it.

 

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[Dusky]

30£ for a throttle shaft with butterfly?? I have some of these laying around if anyone needs it..

[newenglandmini]

I also noticed that the fuel float does not have to be set.  These newer HS4's are much easier to rebuild than the HS2's that came out of my 1951 MG-TD.

 

Finished and ready for installation -

 

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[dklawson]

Your TD should have had H series carbs back in '51.  Did a previous owner fit HS carbs to it?

 

Your HS4 may have the all plastic float.  Those floats are not adjustable per se.  However, you can change its position and set the fuel level in the bowl by selectively changing the number and thickness of the fiber washers between the float valve and the bowl lid.

 

The needle shown in your carb piston appears to be the "swing" type.  I don't know what year it was introduced.  Typically that means the jet bushing is not going to have any adjustment to allow jet centering.  If you can grab the needle and wiggle it, you are correct, you don't need to center the jet.  In the picture it looks like the shoulder on the needle is not flush with the bottom of the piston.  If it is not, work with the set screw and the steel bushing the needle passes through so the shoulder on the needle is flush with the underside of the piston. 

 

On an unrelated topic, did you look at road wheel centers as possible plugs for the center of the steering wheel?

 

Dusky, that was $30 for the shaft and butterfly, roughly 20 GBP.  

[newenglandmini]

Doug, you're correct of course.  They are H2's.  I was going on memory, always a bad idea!

 

It does have the plastic float.  My SU rebuild kit did not contain a fiber washer for the float valve, so I installed it without a washer.  Do I need to install a washer?  If so, can I use a neoprene o-ring as a substitute?

 

My needle does appear to be the swing type.  After reading my shop manual I noticed last night that it was not flush, and I adjusted it accordingly.

 

I purchased a Mk 3 Clubman wheel center on ebay, which I plan to modify to an Austin Mk l Mini appearance.  I first need to determine the appropriate size of the Austin logo.

[newenglandmini]

Doug, I don't know why there was no washer in the kit, but on reflection, there should be a washer under the float valve.  Absent one fuel will leak past the float valve and possibly cause flooding.  I found a perished float valve washer from an previous H2 rebuild.  It has a thickness of 2.5 mm.  My o-ring assortment has an o-ring which fits snugly on the float valve and measures 2.0 mm.  Pending your comments, I could use it to seal the float valve.  In the meantime I'll send a note to MInispares to ask why the kit did not contain a float valve washer.

[dklawson]

I would not use an o-ring because there is nothing to prevent it from being "squished" out of the joint.  If you want to make different thickness washers for the task I would use a set of hole punches and cut them from gasket paper.  by the way, I was recently building an order of parts from Summit Racing and found "gasket paper" did not work as a search term.  Using that phrase I found every possible paper gasket they sold but not "raw material".  If you look for gasket paper online, try the search phrase "gasket material" instead.  Local parts stores like Advance, AutoZone, O'Reilley, and NAPA should have gasket paper but if it is behind the counter you might be at the mercy of the intelligence of the clerk to get what you need/want.

 

Curiously, when I looked up float valves at Burlen and Mini Spares, the pictures of the kits did not show a fiber washer for the valve.  I thought I could identify the washer as part of complete carb rebuild kits.  As I kept digging, I did NOT find the washer sold separately on any vendor's web site.

 

EDIT:  I did a quick search at Advance Auto Parts.  Their web site says Dorman makes multiple sizes of fiber washer but only in 1/32" and 1/16" thicknesses.   I am not sure what inside diameter the jet requires but you may find a local parts store has a few of these fiber washers if you don't want to make your own.

Edited by dklawson, 10 December 2014 - 05:35 PM.

[newenglandmini]

Doug, I have gasket paper.   It will be difficult to cut a washer this small.  I have a hole punch kit which I can try.  I also have a local Advance Auto store, so I have options.

[newenglandmini]

Doug, I've looked closely at the shop manual and noted that it shows no evidence that a washer is used with the float valve.  There was no washer in place when I disassembled the carb.  As you noted, the Minispares image shows no washer.  Barring any convincing info to the contrary, I'm not going to use a washer.

 

I did send an email to Minispares re: this issue, but I have not received a response.