The Ultimate FC

**101 Ron** · 23rd March 2015, 03:41 PM

There are some very good articles about the B81 /B80 motors and its development by the people who were involved and the motors relation ship with the earlier Rolls Royce and Bently motors.
In depth stuff like torsional vibs and combustion characteristics covered.
The B series motor were thoughly tested and developed including alloy block versions and diesel versions of the motor.
Something like 200 different versions of the combustion chamber shape was tried on a single cylinder testing motor.
The B series motors do not handle high compression well without preignition.
What was found that a increase in bore size gave much better than expected power gains.
Thats why we have big bore versions of the B series motors.
Bore size limit became the minmum spacing of the bore to bore in the block.
The B series was a military motor from the start and the combustion chamber and the whole motor was set up for Max power and reliability running on poor and indifferent fuels with good useable torque and power delivery charactaristics.
The F head design was picked purposely over a full overhead valve design to meet the above needs.
After driving the Stalwart with the B81 and now knowing a lot more about the motor than when I first got the vehicle is that it punches above its weight with lots of stuff.
It runs on any old stale fuel I poor down its throat, starts extremely easily, is reliable( bar the ignition system which has now been up graded to electronic), the overall power is not above average for its capacity but the way it delivers it and over a very large part of the rev range.
It is water proof to 2 mtrs even though the stalwart doesn't need it .
80% interchangeablity parts wise between 4,6 and 8 cylinder motors with different bore sizes too.
The blokes running the presector transmissions in other vehicles fitted behind the B81 wouldn't know, drop the motor into the wrong gear and just watch the B81 hang on.
The B81 will if needed run on its governor for hours without damage.
working and tested temp range is minus 40 to plus 50 degree celius.
Dry sump allows running on very steep angles.
Has heavy duty from engine timing case PTO for compressor, power steering and governors ect.
For its time in the 1950s and 1960s few diesels could match it power for its weight with the needs of interchangeablity and military.
Rebuild hours were similar for diesels of the day.
The draw backs was one thing and it comes back to that combustion chamber F head design.............it drinks petrol like a drunken sailor who has pulled into port after a year at sea to a Jamacian rum brewry which never worried the military as the government was picking up the tab.

**101 Ron** · 23rd March 2015, 03:53 PM

The cylinder bore spacing and stroke are the same as a Rolls Royce silver ghost as that's what they started with when set about designing the B series motors.
Progress on the Stalwart has been slow.
The family farm has been sold and I have had to help move things out ect, so personal time has been very short.
A personal issue has left me not wanting to work on it after my normal working days duties.
I have been pulling out my hair trying the refit the LHS rear wheel station and aligning up the tracta joint dogs...........I don't seem to be getting it and the job by your self is heavy and slow.......the sort of job you only want to do once and find, nope that is not working , pull it out again.
I wish I knew how the factory done it...........they must have found a quick way to do it.
If it doesn't go together by the end of the week I will be setting light to the 400 litres of fuel and watch the silly thing burn !....watch the Nowra news reports for vehicle fires.

**Lotz-A-Landies** · 23rd March 2015, 07:14 PM

That would be a very sad event after all the work you've done.

Don't do it!

I know what a tiresome period it is closing up and clearing out a farm. My last load was Christmas Day so I don't envy you one bit. (Still working out what to do with the collection.)

**Sitec** · 23rd March 2015, 08:57 PM

Originally Posted by 101 Ron

The family farm has been sold.......

Know how you feel here.. Dad made the decision about 18 yrs ago to sell the land, and I still clearly remember the day of the sale.. Watching the trucks being loaded with the kit I'd used since I was old enough to drive, and then seeing it go under the hammer at the auction. Hated it, and still can picture it all!

Take a step back, and poss a breather from 'the big project', and get back to it in a month with a clear head.

**Disco_Fever** · 27th March 2015, 06:16 PM

Have spent the last few days reading through this thread - it is a staggering project so far. My old man used to be in the 4/19 PWLH, so big girls like this have always held interest for me.

I would love to get to the show at Corowa next time it is on - when is it?

...and if it isn't too late to name it, I think Splashpig suits it.

Anyhow, thanks for sharing all your trials and tribulations so far. Hopefully there are many more. :thumbup:

Sent from my SM-G900I using AULRO mobile app

**Homestar** · 27th March 2015, 07:49 PM

Originally Posted by Disco_Fever

Have spent the last few days reading through this thread - it is a staggering project so far. My old man used to be in the 4/19 PWLH, so big girls like this have always held interest for me.

I would love to get to the show at Corowa next time it is on - when is it?

...and if it isn't too late to name it, I think Splashpig suits it.

Anyhow, thanks for sharing all your trials and tribulations so far. Hopefully there are many more. :thumbup:

Sent from my SM-G900I using AULRO mobile app

Keep an eye on the website - Corowa Swim In

In March 2016.

**Homestar** · 27th March 2015, 07:50 PM

Originally Posted by Disco_Fever

Have spent the last few days reading through this thread - it is a staggering project so far. My old man used to be in the 4/19 PWLH, so big girls like this have always held interest for me.

I would love to get to the show at Corowa next time it is on - when is it?

...and if it isn't too late to name it, I think Splashpig suits it.

Anyhow, thanks for sharing all your trials and tribulations so far. Hopefully there are many more. :thumbup:

Sent from my SM-G900I using AULRO mobile app

Keep an eye on the website - Corowa Swim In

In March 2016.

**101 Ron** · 5th April 2015, 02:40 PM

Well after about Five months the stalwart is mobile again.
After wasting another day trying to fit that wheel station I was about to find the matches and get some satisfaction and burn the big silly thing and before I knew it the heavens opened up with a thunder storm and I got drenched instead.
I ended up separating the inner and outer tracta joints and fitting the one on the hull separately and then aligning up the splines of the inner and outer tracta joints as another operation.
I ended up using epoxy glue and lock the tracta joint dogs in the correct position.
I now realise one of the reasons I was having so much trouble is the just a lot of the parts are unworn and very tight.
New brake and central lube hoses fitted etc.

**101 Ron** · 5th April 2015, 02:43 PM

The ignition switch has decided to fall to pieces and so far I have not been able to match it up with anything the same both here in Aust or over seas.

**101 Ron** · 5th April 2015, 02:59 PM

The good news is I am able to keep it stored under cover for a little while.
Some of the paint , especially on top of the cabin roof has faded already and needs a respray done due to the weather/UVs.

The vehicle is running poorly at present and I need to get to the bottom of it if I want to play with the stalwart.
I am thinking about still fitting the electric fuel pump, but not this time as a back up, but replace the mechanical pump.
Fit a blanking of plate to the side of the engine block where the mechanical pump would usually go.
Use the existing fuel pipes for the electric pump (should be a easy hook up) and support the electric fuel pump with a bracket from the blanking off plate where the mechanical pump used to be.
Near that location is a alloy housing with I think with connections to a ignition power supply along with the starter solenoid, oil pressure pick up etc......in another words I should be able to power the electric pump without to much trouble because of the shielded wiring system.
I want the electric pump as the mechanical pumps don't like ethanol fuels we use these days and the fact this vehicle will only see occasional use so self priming is good .

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