K_Reparaties - K_Repairs ( 15.08.2010 )

Problem K: SU-Carburettors (added 10/09/2012)

This was inevitable (after 45 years): bought me (from Burlen Fuel Systems) a rebuild kit CRK 254. And a pair of SU-needles (DH).
On MOT got the message that CO was out of scale, went to a mecanic (with a CO-meter) and he measured 8.5 while 5 is the maximum allowed. He cut the engine back to 2.2.
Drove imediately to MOT for a second test and the gauge showed 8.5. The guy at MOT allowed me to screw it back to 2 so I passed.
But on the Wales trip my fuel consumption was almost equal to Geoff's (with a six). Arranged the SU's a little richer and consumption got back to "reasonably" normal.
But as I already had the rebuild kit I decided to go for the rebuild. The strange results showed that proper trimming was getting impossible.
Removed the inlet collector: loosening the throttle-connection, the choke cable, the vacuum-lead for the distributor, the vacuum-lead for (originally) the windscreen washer, and the fuel lead.
Put the stuff on a well lit spot:
You'll notice I cut away (last year) part of the heat-deflecting plate... makes life easier removing and remounting the thing.

Removed the air "filters"... in fact these things only prevent stones, nuts etc to be inhaled in the engine, but I kind of like them.
air filters
Some months ago I cleaned them in the dishwasher (hope my wife won't read this), so guess they're clean.

Removed the valves.

Removed the dash-pots.

Removed the springs and pistons.dashpots

Noticed quite an inequality between the left and right injector. The left one sat almost 1mm deeper than the right(rear) one. Put them at equal height.

Couldn't remove the linkage between right and left carburettor without removing the carburettors themselves.
Noticed a small difference in the linkage between the two carburettors, when pushing the throttle, the rear (right)-one would open slightly slower. Must adjust that.
Notice (btw) the bent 1/2 inch spanner... very usefull.

Different parts on the throttle shaft... if I would have known from before I would also have renewed the hex nut at the left.
Throttle valve is screwed into the shaft. The srews are secured against dropping in the engine by pushing the ends open. Before removing the screws you should straighten the ends.
Once the screws are in and fitting don't forget to "open" the ends.
valve valve2

Had to file down the extruding parts of the throtthe shaft, copper is softer than iron, went well.

Removed the needles, straightforward job, though frightening (first time). Refitted the new ones, without a plyer, must be fitted deep enough.

Added a picture of my old throttle shafts, showed almost 1mm of wear. So not bad that they were replaced. Didn't replace the bushes of the shafts, no play with the new shafts. Didn't (for now) replaced the injectors (though they were in the rebuilt kit). replaced them six-seven years ago and I didn't like (those days) getting them in their correct position. Quite a job to get the rear-right one where it should be. So the needle might have been worn.

Everything refitted the engine started well. So no real problems. Next will be to adjust the CO etc.. hope it'll work but the carburettors are certainly better than they were.

And fuel consumption should go down. We'll see.


Problem K: Lockable fuel cap "locked" added 15/08/2010

MK II Sabras have lockable fuel caps.They were made by CEANDESS Ltd Wolverhampton (#24245/55).

When Jacques bought his GT the car was already dismantled. The filler tube was in a box with the filler cap on it and a key in the slot.
But the key wouldn't turn and as the cap was in the "locked" position it couldn't be removed from the filler tube.
Remark that the filler tube has part # 5243 and the filler cap has #5976, so these parts were already in use by Reliant,
though they're not from the Regal.

The cylinder moved easily, but only over a very small angle in both directions. After several hours of lock picking I learned for sure that the key was
the correct one and that the turning of the cylinder wasn't blocked by the wafers but by something behind it, that should be rotated by the cylinder but was stuck.

So I sawed off the end of the filler tube, close to the rim where the filler cap sits. Then I drilled out the four aluminium rivets that hold the back cover of the filler cap.
The cap could now be freed from the filler tube as the two wafers jumped out. See pic:

The picture shows that a rectangular rim with rounded edges was pushing the two wafers in their outside (locking) position.

Took me again several days, and a lot of patience to get that thing loose:WD40, heating, WD40, tapping, spoke to the Lord quite frequently. See pic

It shows that the thing that shoved the wafers in their outside position was conical, sitting in a conical seat, and driven by same kind of rim on the rear
side of the cylinder.
Those cones, certainly in zamac, are bound to get stuck, the more as the cone is pushed into it's seat by a spring.
I cleaned and oiled everything, replaced the rivets by tiny screws, soldered the cut off part of the filler tube back on the other end
and Jacques had a working filler cap. This was done several years ago.

I write this because today the same conical thing got stuck (not the first time) in my Sabra: got it loose by blowing compressed air in the cap from the locking side.
I had first checked that.the wafers were free. The pressurised air must have pushed the conical thing up against the little spring thus freeing it.
This wouldn't have worked with Jacques' filler cap, that was stuck for over ten years, but mine had been open a fourthnight ago.
Think the fuel vapors wash the lubricants away. Anyway the filler cap is a "black box" - not to be opened - but if you know what's inside you can think about solutions.

Jef Neefs

Problem K: SU-Carburettors (added 14/01/2006)

Recently wrote this and got the advice to publish it on the site:
There's nothing much that can go wrong with an SU and to deal with feeding an engine the right mixture they're a marvellous discovery..

Three normal maintenance checks:

1 There should leak no NO fuel out of them.
    Dangerous spots:
    1 upper side of the floating chamber (where the fuel-lead goes in)
    If it leaks there then needle that should prevent too much fuel coming in doesn't stop the fuel enough
    Means new needles and seats. part #5 (see picture SU_6) (if it leaks there it leaks through a small venting hole)
    Small possibility that the pressure from the fuel-pump is too high, read the manual to check the pressure.
    2 if it leaks on the rubber tube from the underside of the floating-chmber to the jet underneath the carburettor
    Means new jets part #4
2 You should try to locate the "piston lift pin" it sits underneath the suction chamber and is only there for diagnostic reasons
    First test is alsways (engine not running) to push the pin up to lift the piston, if you let go of the pin you should hear a "tick" by the piston falling back on its resting position.  If you can't get the piston up or you don't hear no tick the alignment of piston - needle - jet - suction chamber is wrong.
3 Check if there's still oil in the damper on top of the carburettor (unscrew the black button and pull out the damper).
   Engine oil will do - there's explanation in the text.
 With a warm engine running at idle speed: if you push up the piston lift pin for two seconds and then drop it again, the rpm should go up quickly and drop shortly after you let loose of the pin.
If it raises but stays high your mixture is too high, if rpm drops instead of climbing mixture is too low.
But these are rules from the days that mecanics didn't have no CO-gauges and everything had to be done on intuition, the lifting pin gave good diagnostics then. If an engine is trimmed with nowadays diagnostic devices idle rpm is much higher and mixture is much lower at idle speed.  When I go to MOT I trim my jet-adjusting-screws 7 half turns up to make the mixture poorer, same time I have to adjust my throttle adjusting screws to keep the engine running and it must run on higher rpm then, afterwards I re-adjust them to get the "pof-pof-pof-pof-idle.
 like it when I can count the rpm's.

Last thing you can do is to put your ear against the air-inlets (or use a water-tube as is indicated in the text).
Both carburettors should make the same "hissss", this you can do at different rpms, if they're trimmed wrong there's an obvious difference.
To learn how to recognise the difference you can use the lifting pins to make difference.

If at idle speed there's not too great a difference you can probably adjust the hisss by turning the throttle adjusting screws.  If you can't get it right could mean the balance of the carburettors was set wrong, and if it had been right could indicate serious problems - wear at valves or pistons.

Problem K: SU-Carburettors (added 28/09/2006) Throttle retractor springs

While on the way to Goodwood early september 2006 when I lifted my right foot to slow down the pedal didn't follow anymore.  One of the springs that should close the throttle when the pedal is not pushed, had broken. I was following André and we were both lucky that I didn't follow him too close. A nowadays car should have been towed home but I managed a quick repair and after the meeting and a lovely vacation in UK I went for a replacement.  As allways I did lots of shops and bought some 25 different replacement springs that would all have worked but I had rather found some identical ones.  At last found the closest fit with Hillaert (see adresses).  

The springs on my car (don't know if they are original) were made of a thread of 0.8mm thick, external diameter of the spring 7,45mm wide, length of the body of the spring (all windings next to another) was 56.5mm, and the hooks were adding +/- 5mm to the length of the spring. The ones I have fitted now are made of RVS - "rust resistant steel".  In Belgium we call it INOX(idable).
Haven't driven the car since, but it looks nice (shiny). For about some 20€ Hillaert would remake any pair of springs of about that size.
Fitted the "Hillaert"-springs because they were closest (identical) to the original. Perhaps RVS is harder and will brake sooner than 30years of pushing the throttle.(Jef Neefs)


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