A B20 Story

[the.cern]

The weekend started with Jim and I determined to get the engine stripped. I had not managed to get access to the big end bolts to the front two cylinders. Jim produced from his tool bags a set of Irwin Grip Bolt Removers and a 'wobble extension' for the socket set. The combination of the two allowed the access problem to be overcome and the nuts were removed with ease and without damage to the nuts. I was rather more than flabbergasted with the ease with which he managed this!!

It was then possible to tap the pistons away from the crank shaft which allowed the crank shaft to be removed. The next task was to complete removal of the pistons and liners. These glib statements do not give any indication of the reality of the situation. A 12mm bar was used as a drift on the underside of the pistons to move the con rods from the crank shaft. Out of the six pistons only one moved within the liner, the others remained stuck in the liner and it was the liners themselves that moved in the block. Even the one that moved did so only for 20mm and then stuck and the liner itself moved. Having removed the crank shaft it was easy to remove the pistons and con rods complete with their liners from the top of the block. The last few fixings etc were removed from the block and that now awaits cleaning. That took all of Saturday, Sunday was time for Jim to get back to the Gussie shell, in particular the floor under the driver's feet which had been very badly patched. I removed all the engine parts from the workshop. Even though it will be totally rebuilt, I do not want the debris resulting from the cutting and grinding operations on the Gussie shell getting into the engine.

So Jim made a lot of mess and a lot of noise whilst I continued with the delicate task of separating the pistons from the liners. I do not have a photograph of this but I think you will get the idea if I say it involves a 40mm dia. tubular steel drift, the liner balanced across the jaws of a vice and a 4lb club hammer!!!!!!!!! I have managed to separate three pistons from their liners and removed the gudgeon pins thus freeing the con rods. Needless to say, new pistons and liners will be provided. As can be seen in the photographs, one of the con rods is bent, that too will need to be replaced. The good news is that the crank shaft journals have not previously been ground, although it may be that such work will now be necessary. I have yet to remove the plugs from the ends of the cooling tubes, Clive Beatty suggests they should be broken to remove them, I am investigating options to remove them undamaged!!! That is where we are at the moment, more to follow ....

The first photograph show the liners projecting from the block and the second the bent con rod with its piston. The state of this piston is typical of the others removed so far !!!!

                                    Andy

[DavidLaver]

THE news here is "the crank shaft journals have not previously been ground".  Brilliant...

Shame about pistons and liners, but no surprise and "off the shelf" for all no small expense.  If budget becomes an issue there are excellent second hand sets kicking about from all the rebuilds where "having gone this far it seemed stupid not to put in new".

David

[stanley sweet]

What would cause a bent con rod to start with? Hitting valves?

[frankxhv773t]

I think hitting the valves would bend the valve first and have left a valve shaped dent in the crown of the piston. Would the piston seizing do it? Or would that be obvious from the state of the sides of the piston?

[the.cern]

I have no idea what caused the bent con rod. I had no incident in the time that I was driving it. Hydraulic lock on that one cylinder could be the cause ..

                          Andy

[the.cern]

Today I managed to free the last two pistons from their liners. One was so tight that I had knocked a hole in the top of the piston before I managed to drive it out!!!

So that is the engine totally stripped, now I need to find a reputable place to take the parts to get a professional judgement on what should be replaced and what is still serviceable.

My gut feeling is that the valves and their guides are suitable for continued use but the rest of the 'normal' rebuild items should be replaced. The sump seems undamaged, the block needs welding and the heads are a nightmare. One thing is certain, it will not be cheap!!!!

                              Andy

[simonandjuliet]

I have sent my Aprilia engine to Serdi in W London (recommendation from David L) for the same "professional judgement" - will let you know how it goes .....

[the.cern]

So it has been 10 weeks since I lasted posted on this thread, just where does the time go?

I can assure you that I have not been idle ..... I still have to take the crank to be checked over, but things have moved on in other areas. By virtue of a lot of effort and countless hours on the internet I have managed to put together a stash of parts that will allow me to rebuild the engine!!! This was made easier by my decision that I would not attempt to find secondhand heads, but find a way to repair the originals. The other parts are relatively easy to source, albeit some are a tad expensive. The operative word here is 'relatively'!!! However, it can be done.

That was mainly a desk top study, but it also involved a bit of travelling including a trip to Italy. In between all this I continued to strip and clean various parts. There was over 12mm of sludge in the sump!!! It will be interesting to see what is in the oilways of the crank when I remove the plugs!!! I did not restrict my efforts to the engine, I have opened up the gearbox and made a thorough inspection, no obvious damage and not an excessive amount of swarf on the magnetic sump plug. There were chatter marks on many of the teeth, but nothing that should cause me too many problems, I hope!!!

The latest task has been to strip the drive shafts. I am lucky in that all the rubber boots, despite being extensively cracked and in need of replacement, have managed to retain oil and therefore there has been no excessive wear in either the pot joints or the outer UJs. I have sourced new needle rollers and seals so they will be rebuilt and set on the shelf for installation in due course.

That is where I am at the moment, I do need to find an engine man I feel I can trust to do the job properly.

I have started on a shopping list for Cavalitto .... it will be interesting to see how long it eventually gets!!!

                                                Andy

PS the Gussie is also progressing so, if you are interested, do have a look at that thread.

[Parisien]

Getting there Andy, its a slow slog but worth it in the end!

P

[DavidLaver]

In your shoes I'd at least visit Jim Stokes empire (and can I come too!!!).  I never got as far as having them do any work for me but by research and reputation the hourly rates used to be reasonable as was the turn round. 

The other part of their reputation is just how far things can add up but that's the two-way-street of being specific about exactly what you want them to do and what you'll do yourself rather than just giving them a box of bits and "whatever it needs" as their brief.

Omicron bills also have the reputation of being several pages longer than expected but they are also very generous with time on the phone for inquiries and are also (certainly used to be) open to doing distinct and limited work on individual components.

Can anyone else here easily ask the question on the VSCC forum?  While I am a member I've never used it.

David

[the.cern]

Oh dear! Where has the time gone???

I have been busy, but not wholly on the B20. The Gussie has been a distraction and getting a lot of attention.

The engine has been weighing heavily on my mind. I have had the crank checked and what looked like an untouched original crank has actually had quite a bit of work done to it. The main journals have been been ground, metal sprayed and finally ground back to original specification. The problem is that the metal spraying has started to fail adjacent to the main journal oilways!  I must decide whether to have the sprayed metal  ground off, then have the crank built back up using the submerged arc technique and ground back to original specification or to take a chance and use it as is. The big end journals are in good condition and do not require work.

The heads and the block have been left with an engine specialist. The news so far is that the block is ok, the snapped studs have been removed and it is ready to have the liners reinstated. The damaged valve spring seats in one of the heads have been machined back, new seats made and installed. The valve guides have been sleeved, a light skim and that head is ready for action. The other head with the severely damaged combustion chambers is a different matter. They are still working on it .... the valve seats have been removed and the weakened areas machined back. Then it is a matter of welding in new material, machining back, welding in more material, machining back and repeat and repeat and thus slowly building up the damaged areas. Hopefully this will be successful, but there is no guarantee!!!! Time will tell.

I hope to get some news soon and will up-date as and when ....

                                                         Andy

[the.cern]

This week I got fed up with removing rust, paint and general muck from hard to reach parts of the Gussie and decided I needed to make something. So why not something easy like the petrol tank filters in the B20? These take the form of mesh cylinders around the main and reserve petrol pick-up pipes. They are item 9 on TAV 11.

The photographs show the poor state of one of the originals, that is the good one!!! Basically they are a cylinder of brass gauze supported on a brass frame attached to the drain plug with a brass cap on the open end through which the petrol pick-up pipe passes. The whole assembly is soldered together, so this should not be too difficult eh??

In the original the brass frame is stamped out of thin sheet brass, as is the top cap. I decided to use a brass tube and to cut slots in it as the frame and to fabricate a replacement brass cap from two brass washers, 2.5mm diameter copper wire to separate them and a 2mm thick Viton washer to seal it. Having the 2mm Viton washer between the two brass washers which are 2.5mm apart allows the washer to move laterally to accommodate any out of trueness in the pick-up pipes. It took something like 12 hours to make the first one. That allowed for working out the best MO, finding the tools and generally faffing about .... the second one took less than 3 hours!!!

I first made the brass frame, I drilled it out roughly and then cleaned the slots up with a small mill in a Dremel type tool. The brass gauze was cut to size, the washer was cut from a sheet of Viton (I could not find any to buy on the internet) and the copper wire was cut and bent to size. All I had to do was solder it all together!!! No problem!!!  I started off with my usual high power butane blowtorch, but that was too fierce so I dug out the 'normal' one. That comfortably soldered the frame to the drain plug. Then I made the top seal from the brass washers and the 2.5mm dia copper wire. Not so easy, the slot into which the Viton washer had to fit kept getting filled with excess solder. Obviously I had to omit the Viton washer whilst soldering the two brass washers and copper wire assembly as it would have been destroyed by the heat of the operation. Eventually I was successful and a trial assembly with the Viton washer proved all was ok. Then I had to solder the washer assembly to the brass frame .... that was when the washer assembly fell to bits , the solder having been melted again!!! This happened another time before I eventually got the two stuck together. The final step was to solder the brass gauze to the frame. Whilst attempting that the heat caused the washer assembly to come unsoldered  again and it fell off ... in bits!!!! I was a little annoyed!!!! I got the washer assembly back together again and also back on the frame. Now I knew how careful I would have to be with the blowtorch!!! So I was careful not to get too much heat near the washer assembly .... and the price I paid ... burnt a hole in the gauze!!! A second piece of gauze suffered the same fate!! Then I remembered my mini blowtorch used for electrical wiring ... That did the trick and at last I had a complete filter. A little tidying up and fettling and I could relax. The second filter was so much easier to make, although I still needed 3 attempts to make the washer assembly!!!

Photographs, a picture speaks a thousand words!!!

[the.cern]

More photographs ...

[the.cern]

 ..... and finally ...

[fay66]

St Andy

Brian
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