A B20 Story

[the.cern]

In fairness, that was the only stud out of the 32 that was obviously corroded. However, as Brian says, you cannot be sure what they may be like after all these years. Therefore I will replace them all, including the one that was sheared off at the level of the top of the block on some previous occasion!!

                             Andy

[chriswgawne]

Andy,
These days after rebuilding many Aurelia engines over the years, my studs of choice are used original Lancia ones which exhibit NO signs of corrosion or necking. I have bought and used new studs from all the reputable suppliers over the years and had problems with all of them one way and another.
Chris

[the.cern]

I thought I ought to try to keep up the momentum so today it was back to the workshop to start on the heads.

Before that, time to get the valve spring compressor from the garage. This has been kicking around and getting in the way for, literally, decades. Yes, you've got it, couldn't find the bl**dy thing anywhere!!!!!! S*d it, Machine Mart is up the road, I will buy another.

I set the first head up and attacked it with a wire mop brush in an electric drill at about 700rpm, brilliant. Then a 'pencil' wire brush in the drill to get into the nooks and crannies. The other head was given the same treatment and both looked a lot more respectable, but I was very concerned about the extent of the corrosion to the hemispherical steel combustion chamber insert for the rear cylinder of the left hand head. I was looking for an off-cut of 1mm plate to clean out some of the corrosion products when I found the valve spring compressor, miraculous!! Please note this was BEFORE I went out to buy a new one, even more miraculous!!!!!

So, with my new toy I set about the valves. I have not stripped a head for probably 30 years, but it all came back to me and in a very short time I had all twelve valves out and bagged up. A worrying moment when I could not find the valve stem caps for the exhaust valves clearly listed in the parts book ....... but wait, that is for the B12, a quick check, thank goodness, not listed for the B20!! Out with the electric drill and more cleaning up.

Two main worries at the moment:- firstly, on the LH head, the corrosion in the combustion chamber insert mentioned above and secondly, on the RH head, two of the bosses onto which the inner valve springs are seated are corroded and cannot perform as required. Two worries, two questions, is it possible to replace or repair the combustion chamber insert? Also, is it possible to build up and then machine the valve spring bosses. If the answer to one or both of those questions is no, then I will be looking for one or two heads!!

The photographs show the heads after the preliminary clean, then the heads with the valve gear removed and finally, a close up of the corrosion to the combustion chamber insert.

I will add a little more later, mainly requests for help and advice ...

                                  Andy

[fay66]

Andy,
that looks a lot better!
Nice to see another original cast ally workmate being put to good use, though to be fair yours looks like it's had a harder life than mine

Brian
8227

[chriswgawne]

Just on the subject of studs versus bolts, it seems obvious to me that one should stay with studs. Original studs have a coarse thread to screw into the block ( which is not disturbed very often) and a fine thread for the nuts to hold the head with the correct torque. The torque settings (and sequence) are important and using a bolt with coarse thread into a helicoil in the block will not be as good as originally conceived by Lancia. Inserts are preferred to helicoils for the block which means more work......but one then has total confidence in using the correct torque settings. I remember once torquing the final nut on a B20 head on an old helicoiled stud and the bigger pulled out.
Where bolts/inserts are very handy is with the exhaust manifold/cylinder head joint especially for where tubular manifolds are used. I have spent many hours tightening these up using the original studs and brass nuts wiggling a non standard manifold into place with the steering column in the way on the rhs. The heads however must have proper steel inserts to do this, not just helicoils so I only have it on my race car engines where head or engine changes can often be under time pressure.
Just my opinion, and of course Lancia engineers always knew what they were doing and why.
Chris

[the.cern]

Today, despite the lure of the sun, was another day in the workshop.

Off came the rear alloy cover plate, the front prop shaft coupling and the flywheel. Then the starting handle dog, surprisingly not a battle and the timing chain cover plate.  First question. Should there not be timing marks on the camshaft sprocket and the crankshaft sprocket or is the cam timing set from scratch on rebuild?

Second question, is there an easy way to remove the head studs? Chris' post suggests I have a battle on my hands!!! I have sprayed WD40 on them several times over the past two days and have given them a few taps with a hammer to try to break the corrosion products and get the WD40 into action!!! The good old 'two nuts locked together' MO has so far undone five studs and failed on another five, only another 21 to try. Ah, yes, there is one more stud ... that is the one that had been sheared by others and ignored!! In blissful ignorance I had been driving the car in that state ... that makes one wonder exactly how critical the torque settings and tightening sequence is!!!

Just three photographs ..... 1) flywheel in 'as found' alignment
                                         2) flywheel with Lancia marks in alignment. Note this is 60 degrees different to the 'as found' alignmnet
                                        3) timing chain, this surprised me being so compact

More to follow as and when ...

                                                       Andy

[simonandjuliet]

Re stud removal, I have had success with one of these :

http://www.amazon.co.uk/Draper-14156-2-Inch-Heavy-Duty-Extractor/dp/B0001K9Q1S/ref=sr_1_4?ie=UTF8&qid=1431324510&sr=8-4&keywords=stud+removal+tool

Can't you push the engine outside and enjoy both the workshop and the sunshine ?

[the.cern]

Thank you Simon, I have seen these, but have been wary. One to consider.

As for working in the sun, the workshop opens directly onto the public highway, so not an option. I usually have the doors wide open and this is great in the morning as they face east, but not so good for the rest of the day. The disadvantage is the number of times I am interrupted by passers by, Although there have been some very interesting characters .......

                                         Andy

[chriswgawne]

Regarding the cylinder heads, apart from the corrosion the other major concern these days is what thickness the heads are........I.e. how much has been planed off them?
Good useable 2.5l cylinder heads are few and far between these days and if replacements were ever made they would be expensive. It's not a good idea to start using thicker head gaskets to compensate.
I am away and can't remember the critical minimum overall head thickness but can  I suggest you measure them Andy?
Chris

[chriswgawne]

Apart from the corrosion issue, what is also v important and potentially terminal ref the heads is their thickness....I.e how much has been planed off.
Good useable 2.5l heads seem to be in very short supply these days and you can't just use a thicker head gasket to compensate.
I am away at the moment and can't remember the critical min overall head thickness but I suggest oh measure your heads Andy.
Chris

[fay66]

Today, despite the lure of the sun, was another day in the workshop.

Off came the rear alloy cover plate, the front prop shaft coupling and the flywheel. Then the starting handle dog, surprisingly not a battle and the timing chain cover plate.  First question. Should there not be timing marks on the camshaft sprocket and the crankshaft sprocket or is the cam timing set from scratch on rebuild?

Second question, is there an easy way to remove the head studs? Chris' post suggests I have a battle on my hands!!! I have sprayed WD40 on them several times over the past two days and have given them a few taps with a hammer to try to break the corrosion products and get the WD40 into action!!! The good old 'two nuts locked together' MO has so far undone five studs and failed on another five, only another 21 to try. Ah, yes, there is one more stud ... that is the one that had been sheared by others and ignored!! In blissful ignorance I had been driving the car in that state ... that makes one wonder exactly how critical the torque settings and tightening sequence is!!!

Just three photographs ..... 1) flywheel in 'as found' alignment
                                         2) flywheel with Lancia marks in alignment. Note this is 60 degrees different to the 'as found' alignmnet
                                        3) timing chain, this surprised me being so compact

More to follow as and when ...

                                                       Andy

Any chance of introducing a bit of localised heat?

Brian
8227

[the.cern]

Regarding the cylinder heads, apart from the corrosion the other major concern these days is what thickness the heads are........I.e. how much has been planed off them?
Good useable 2.5l cylinder heads are few and far between these days and if replacements were ever made they would be expensive. It's not a good idea to start using thicker head gaskets to compensate.
I am away and can't remember the critical minimum overall head thickness but can  I suggest you measure them Andy?
Chris

Thank you Chris, I had not thought about that little concern!!! I will measure them tomorrow. Maybe it is just as well at this stage that I do not know what the minimum acceptable thickness is. What exactly becomes a problem if too much is skimmed off?

I think the corrosion/erosion to the steel combustion chamber insert is quite visible and comments are sought. Attached is a photograph of one of the corroded/eroded inner valve spring bosses. The spring has no proper seating and therefore will not provide the  correct amount of return force to the valve. The outer spring seats are not affected. Some of the washers that sit between the valve springs and their seats are badly rusted and I will try to source replacements. This affects both the inner and outer springs.

More to follow

[the.cern]

Today was a let's see how many studs we can get out day.

In short, I cannot remember what the final score was!!  However, the day went something like this. All studs, except the badly corroded one have been treated with WD40, several times, tapped with a hammer, several times and then the two nuts locked together treatment.

The result ......

Still resisting all attempts 8
Not attempted                 1  (the corroded one)
Sheared by others            1
Sheared today by me       1
Freed                             21

Prognosis:-  one of the 8 still resisting will undoubtedly shear, it is necked by corrosion at the level of the top of the block. I will be lucky to get the corroded one to shift, I will not attempt this until I get the tool recommended by Simon as using the two nut method will simply shear the stud in the corroded area. Of the 7 others still resisting, I will persevere, but think I will probably be lucky to shift even 4, the rest will shear!!! So it is likely that I will have at least 8 sheared studs to deal with. The best scenario I have read of so far is to grind the stud down so that it is flush with the top surface of the block, determine the centre, centre punch and drill out, eventually picking out bits with a point and cleaning everything up with a tap. Any other suggestions are warmly welcomed!!

                                          Andy

[DavidLaver]

Chris,

With an over-skimmed head is having low compression pistons made an option?  Its desperate and expensive but might permit the use of otherwise excellent heads.  Perhaps a better option than getting into wholesale rebuilding of rotten castings...

All,

I've a memory from somewhere of an Aurelia that dropped a valve having a new combustion chamber machined from solid and welded in...it could have been another car entirely or merely an insert shell...its the sort of story that someone at the Aurelia lunch would remember, or you'd know 100pct it was my imagination.

Andy,

If the logistics work between us I've that tool you could borrow.  The one advantage is that it grips the stud lower than the two nut method but I'd say its little better than something vicious from the plumbing tools department. 

If it came to drilling out, if it was me, I'd leave them as "damage to address" until you were sure that the heads were keepers, even then I'd be tempted to add it to the jobs for the machinist to attend to after welding. It will be a long enough list that a couple of stuck studs will be neither here nor there and you've plenty else to get on with.

David

[DavidLaver]

...and well done indeed shifting that many so far!!!