BMC 9/16 Kigass pipework

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mark williams
Posts: 27
Joined: Tue Jun 20, 2023 2:24 pm
Wales

BMC 9/16 Kigass pipework

Post by mark williams »

can anyone tell me the size of the pipework on the kigass system on a BMC 9/16 its an early 950cc model pipes are broken and I want to replace hopefully with copper and new olives

many thanks in advance

mark


Nowtnew
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Re: BMC 9/16 Kigass pipework

Post by Nowtnew »

Hi Mark

It's 3/16 inch outside diameter.

Incidentally, imho the kindest thing the Kigass system can do for you is to rot away.
If John Poulter sees this post he will no doubt give you the benefit of his considerable experience and wisdom on this topic so don't take my jaundiced view as gospel on its own.

Regards
Ley154
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Re: BMC 9/16 Kigass pipework

Post by Ley154 »

Yes 3/16 is it. I presume you have all the originals so you know the routing. Surprised you have Kigass on an early Mini ( that's 1966 ) The kigass system was fitted in production at the start of 1968 ( last year of production of the Mini ) and could be retro fitted - tech bulletin 168 dated 11 April 1968. The modification included removing the heater plugs, wiring and fitting blanks in the head and relying solely on the one new heater plug in the inlet manifold. This is a special heater with an exposed element, not the common CAV thermostart plug. Brief history: Engines made in 1965 used 12 volt heater plugs. By mid 1966 9 volt plugs and a ballasted relay system was used to improve starting. These stayed hot when the battery voltage dropped due to starter cranking pulling the batter voltage down. ( I always fit a 95ah battery same as used in a MF135 ). Then followed a batch of engines that had the heater plugs and kigass until in 1968 they fitted just kigass. I know the engines do start on just kigass but no better than any other system and if one of mine had it I would remove it and fit either the 9 volt system or a modern fast heat plug which requires drilling the head. Both types require a new wiring harness. Any way after all that rambling your answer is in the first two words! Just check that the kigass pump is working with no leaks before you bother as I don't think replacements are easily found. John Poulter.
mark williams
Posts: 27
Joined: Tue Jun 20, 2023 2:24 pm
Wales

Re: BMC 9/16 Kigass pipework

Post by mark williams »

Many thank to you both and especially John for the in depth reply,
have only had the tractor 2 days, and was given glow plugs and relay with it
the Ki-gass was plumbed up wrong as the return to tank was at bottom so holding tank was always empty,
the pump is functioning and the heater is working,
I think the poor thing has been having the rewarded easy start as there is a hole drilled in the air intake upstand,

I will be re wiring it once I get the bits I have ordered

and this tractor had drum brakes as well as the discs all be it with all shoes etc removed


thank you once again

mark
Ley154
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Re: BMC 9/16 Kigass pipework

Post by Ley154 »

Attached picture of the kigass manifold with the special fuel feed tap that sprays the fuel down onto the exposed coil. If you have been given 12 volt heater plugs ( most modern aftermarket ones are, the original 9 volt ones are Champion CH39 ) then you can wire them straight to the starter switch - no relay or ballast resistor is needed. Note in the picture the manifold has been incorrectly fitted with a thermostart so the fuel pipe would not be there with the proper heater coil. JP
Image
mark williams
Posts: 27
Joined: Tue Jun 20, 2023 2:24 pm
Wales

Re: BMC 9/16 Kigass pipework

Post by mark williams »

Hi John thank you for the reply
I have taken the blanking bungs out of the head on the 9/16 the bungs replicate the glow plug as far as the taper on end of the smooth section
but the holes that continue into the head seam to not have been drilled there is shiny metal blocking the entry of the title tip section of the glow plugs,

are the pressed in blanks or just not drilled ?

thanks in advance

mark
Nowtnew
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Re: BMC 9/16 Kigass pipework

Post by Nowtnew »

When I removed the 'blanks' from my mini, three were as the top one; just one was intact.
It seems you have been even more unlucky.

Image

I'll tell you how I got mine out when John has commented.
Ley154
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Re: BMC 9/16 Kigass pipework

Post by Ley154 »

Notnew has been there seen it and done it. Unfortunately the tips on the blanks have broken off in the head. I am interested to know how he got them out but drilling would be the normal method. Without removing the head, If you put grease on the tip of the drill and keep removing it you may be able to remove the swarf. If you remove the injectors and make up a bung attached to an airline ( see photo for the one I use when modifying the head to take special plugs ) and apply 10 psi with the piston at TDC with luck none of the drillings will enter the pre-combustion chamber. The finished hole size is 11/64. Another method is to just plough the drill in and not give a damn about the swarf! It seems to work for some but I wouldn't get away with it. How do you do it notnew? John Poulter.
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Nowtnew
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Re: BMC 9/16 Kigass pipework

Post by Nowtnew »

To put all this into context, I've got to bore you with the complete story.
Having struggled with the Kigass system, I decided to convert to glow plugs. While the Kigass system seemed to theoretically emulate the 'blowlamp down the air inlet' system of starting a diesel, it couldn't preheat. It only came to life once the engine was cranking and therefore quite a lot of battery Coulombs had been consumed before you stood a chance. If the battery was at all weak that chance was zero.
I took out number 1 cylinder blank, the one which came out intact, obtained a set of glow plugs and set to work. Alas all the others snapped.
Fearful of the consequences of drilling and mindful of the difficulty of obtaining spare parts (This was late 80s)I decided to let things stand with one glow plug and Kigass. All the time it bugged me and one of my 'trials' was to run the engine with the top bit of the blanks removed to see if the remnants would blow out. I was careful to ensure that nothing was in the line of fire, recognising that these 'pins' could make a pretty dangerous projectile.
They did not yield. I thought of just driving around in this state but decided it was too dangerous.
The next trial (in the 'noughties') was to see if I could move the pins with a punch. I selected one cylinder and using a 1/8 punch I tapped away with a small hammer. I felt it move slightly and then wondered if I would do more damage if I knocked it inwards so I stopped and decided to run the engine to see what happened. Nothing.
Spurred on, I decided to continue my tapping while the engine was running at idle; again being very careful to keep out of line. I felt the pin become looser and stood aside as sounds of gas leakage started just before the pin blew out. I successfully did the remainder in the same way. I never found the pins as I had been careful to make sure there was nothing in the way that could have caused a ricochet. I imagined the projectile to be similar to an airgun pellet.

The pins are 1/8 inch diameter therefore the csa is 0.05 square inches. So if the cylinder pressure is about 250 psi at tickover the force on the pin is less than 13 pounds. I am not recommending this technique as a sensible and safe method. The potential hazards are self evident.

In any event bear in mind that once the 'blank' in its entirety is gone then it will be necessary to put in a glow plug as the absence of the pin will affect the clearance volume and thus the compression ratio. Using the 11/64 drill before you screw in the plug to clear any carbon or other dross is vital. ( I got away with a 4 mm drill but the full size would clearly be better)



Regards

PS Just remembered. The original starter (ignition) switch had a reverse position for preheat. This was awkward but as it was knackered anyway due to someone using a screwdriver instead of a key, I replaced it with a 3 stage switch which is much better.
mark williams
Posts: 27
Joined: Tue Jun 20, 2023 2:24 pm
Wales

Re: BMC 9/16 Kigass pipework

Post by mark williams »

many thanks I will try the drift and engine running option first
as I dont think all of the shank that remains is captive by he head, there must be the end of it protruding inside the combustion chamber to glow, and if drilling tis will no doubt drop in, unless I can get a small stud extractor in it?,
so my plan is:-
1 get engine warm
2 remove blanking plugs
3 soak with penetrant
4 hang a leather welding apron to catch any flying remnants
5 run engine for a while
6 re apply penetrant and try tapping in a little with drift
7 try drilling and using small stud extractor
8 just drill and keep swarf to a minimum

thank you all

mark
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