To Mix Fuel and Air

I got my very own POSA FUEL carb today from, of all places, Greece.  More specifically the Isle of Crete.  This POSA was one of a group that was converted at the factory for use in light aircraft.  It has a fuel mixture valve and a rod operated air slide with no slide return spring.  It is a 32mm throat and has only had about 150 hours of run time total use.  I think I have the basis for a good fuel/air mixture device that is super simple.  With the bits of tuning information I have turned up from the light aircraft people this POSA should do everything I need.  It won’t be a quick fix and I will have a steep learning curve but the potential is there.  This should provide the means to make more precise tuning adjustments for varying conditions much quicker than with a conventional carb.

Just in case the term simple for a carburetor might seem to be overstated, here is the POSA Fuel completely disassembled.  Prior to having it in hand I had only read the patent and looked over the patent drawings.  It took all of five minutes to take it all apart.  There is one casket and two o-rings total for the whole carb.  Very pleased I was able to get one in such good condition and with mixture control.  This of course won’t be the last time I’ll be talking about the POSA, I can tell you!  Of course if this thing really drives me nuts I can always drop back and use the AMAL Mark II.  Nice to know I have a reserve.

The Works!

BROOKLANDS: Where the Magic Happened

                                         Brooklands sometime in the 1920s.

A.F. Locke-King, with his own money, built and opened Brooklands on June 17, 1907.  The intention of building the track was to provide the British motor industry a place to speed test.  Performance testing on a closed circuit would bypass the 1903 law relegating motor vehicles to a top speed of 20kph.

Brooklands was also envisioned as a profit making enterprise to capitalize on the growing interest in motor racing as a spectator event.  To satisfy both aims the track was built as a 100 foot wide 2.75 mile long banked oval.  The banking approached 30 feet high in places and the banked turns were of 30 degrees.  A later addition of a finishing straight increased the lap length to 3.25 miles.

In the early 1900s the technical ability to lay tar macadam on banking and the expense of laying asphalt lead to the choice of building with uncoated concrete.  This meant that all of the track sections had joints since by 1907 the technical ability to lay continuous sections of concrete had not been perfected.

Even with current suspension technology driving a long high speed distance on a modern interstate can be jarring.  The ability to smoothly joint concrete still seems to be in the future.  It can only be imagined what attempting a speed trial at Brooklands was like.  Some of us that still insist on riding hard tail girder fork cycles do have a perspective on what type of hard rider it would take to be an hour in the saddle at speeds of 100 mph or more.  I think young Fergus Anderson was one of those legendary hard riders.

I couldn’t find any Brooklands record photographs of Fergus Anderson.  This shot of Eric Fernihough on his Brough-Superior JAP 996 in 1937 gives a good approximation of what it would have been like at speed on the Brooklands banking for young Mr. Anderson.  Borrowed from Eric at Historic Engine Company.

MAGIC of the JAP Engine

Recently I was privy to a reasonable question ask regarding the fascination for JAP engines.  My immediate reaction was to think of the numerous speed records that JAP engine racers have made and broken over many years.  Of course it's also the look and the sound of them.  Thinking about the question of fascination and of course, in my case addiction, I reread what is probably the best example of the JAP magic.  It’s a story of record breaking as related by Jeff Clew in his history JAP: The End of An Era. 

By 1932 the JAP Speedway engine was well established as the engine to use if you wanted to win on the cinders or on a grass track.  The circle track racers loved it but the remainder of the racing community looked on it as a freak.  One young road racer didn’t have the same opinion of the engine.  As a result he determined to win a new trophy put up at Brooklands by H.J. Bacon for the first privateer to cover 100 miles in an hour.  Fergus Anderson was that young racer.

Mr. Fergus Anderson planned that if he could lap at around the 104 mph mark he could take one pit stop and carry off the hour record and the trophy.  To do so he went off to the Tottenham factory with cash in hand for an engine.  As his luck would have it the factory had five speedway engines ready for dispatch.  It has to be remembered that at this time the factory was building the engines mostly by hand and then dyno testing for output with a complete strip down and inspection before dispatch. 

As a result Fergus picked up an engine which was guaranteed by the factory to produce 37.8 bhp at 5,750 rpm.  Apparently he chose one of the five at random.  Fergus then installed the engine in a Grindlay-Peerless machine of Bill lacey’s.  His tuner for this escapade was Tommy Atkins who had about four hours with the engine before the attempt was made.  With a fresh engine and quick tuning Fergus took to the Brooklands banking, April 21^st of 1932, for his go at the record. 

In his first lap from a standing start Fergus brought the virgin engine across the line at 98 mph.  His second lap was a crazy fast 109.22 mph.  For the hour record with trophy Fergus averaged 100.52 mph.  All of this with a virgin engine, four hours tuning and an engine that was never designed for this type of racing. 

That's the JAP magic!

    This is close to what the engine, Fergus Anderson ran for his Brooklands speed fest, would have looked like.  His engine would have been a bit fresher looking as it was perhaps only 72 hours out of the factory dispatch room.

Bill Lacey was famous in his own right for his Grindlay-Peerless based Brooklands racers.  This is an example of one of his machines which is in the Brooklands Museum.  This is very close to what Fergus Anderson’s machine would have looked like for his Brooklands hour record.

ADDICTION and WAITING FOR PARTS

I have heard from people that have gotten skin illustrations that it can be addictive.  You get one and immediately start contemplating the next illustration.  That is what I have heard.  Speed drilling is addictive just as tattoos are.  I started with drilling and cutting the rear brake plate and I’m all ready contemplating what other bit and pieces could benefit from drilling.

I’m happy with the way this turned out.  The finish is not exactly what I envision for the end result.  There is a great deal of garage and mock up, tear down time before the wheel actually hits the road.  So if figure close is good enough for now.  I will touch up the finish when it’s time to bolt everything together in preparation for pronouncing it complete.

I will admit that waiting for parts is painful.  Even if that part may not be used for months and months.  It’s nice to know it’s on the shelf.  Still waiting for the POSA carb and word about my case rebuild. 

JAP at Auction

Today at the Motorclassica auction in Melbourne this went across the bloc.  A JAP Twin-Port Racing Engine: Engine no.1932 JORZ/D.  It sold for AU$3,360 inclusive of Buyer's Premium.  No details on the web site regarding condition but looks like it could be mostly there.  Somebody got a great engine for a project. 

Volatile bits and pieces

Later engines from the factory seemed to have had the intake sized so that they could use the new AMAL 932 carburetor.  This would have had a 32mm throat size.  Based on measuring up the heads I have available that works out.  However racers always try and get an edge so the AMAL Mark II I have is actually a 34mm on the intake manifold side and 43mm on the air side.  This may or may not present a tuning challenge. Since it's more normal, getting the engine to run well with the know quantity of the AMAL should prove to be simpler.

I got one!  I have luckily, for the ever curious part of me, been able to score a POSA Fuel carburetor of 32mm.  Even better yet it came off a light sport airplane and has had a fuel mixture control added.  Now I have a simple but reputedly enigmatic carburetor to eventually play with and either be successful or frustrate the hell out of myself.  No matter what happens it will be educational and there will be something learned.

Mechanics Warning

This is the JAP steel con rod that divorced the big end pin in an oil deprivation and heat induced marital disagreement.  The partnership strife was caused by inattention to the screws holding the Pilgrim oil pump to the timing case and oil stopped flowing when the screws backed out.  So the warning is, if you are assembling an engine and during your pre-flight checks be sure of the tightness of all those important pesky little nuts and bolts.  It will be worth the time it takes.