Autobella 2010

February 21, 2010

Autobella

The FIAT Car Club of Victoria held its annual concourse, and we invited ourselves to attend.

Bianca. Competition category winner Phil Buggee's orange Punto Diesel is in BG

We’re lucky we didn’t have to drive the 15 kays to Como Park because we were fouling plugs even getting onto the trailer. This is a car that does not like to idle. Theories of cause could possibly be due to oversized pump jets or the dizzy arrangement. We will be able to isolate that soon if we move to a Megajolt system which would allow us to control our spark a lot more accurately and send bigger sparks into the cylinder. It will also give a more reliable spark at high RPM. There will be no movement on that front until the first couple of track days prove that the plugs will be a problem. There wasn’t so much as a mutter when it was running properly on the dyno. so we’ll see.

My pick for people's choice

It was nice to see so many Italian classics, including this Stirling Moss Masarati, which sent grown men running in its direction. Also-rans include a fleet of Ferraris, Lancias and a few Alfas.

Stirling Moss Masarati

Although we didn’t exactly bring home the silverware, there was some encouraging interest in the car. Comments about our preparation were positive, and hopefully this will translate into reliability and consistency when we finally hit the track.

Julian, Sam and Andy

The only thing missing in the end was stickers to make our X look like a proper racer – ‘home brand’ racing obviously doesn’t win the judge’s vote. Phil Buggee’s orange Punto Diesel ended up winning the competition category. It was by far the most prepared (and probably most raced) entry, but being a fairly stock diesel, it was a bit boring when compared with some of the other modifications and older exotica in attendance.

Next stop, Phillip Island.

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Jetting

February 14, 2010

As promised, our jetting for twin Dellorto DHLA 40, emissions version.

NOTE: This will probably NOT WORK well for non-emission spec Dellorto or Weber sidedrafts on a similar engine.

Idle: 65 (this must be around the 45 mark if you run non-emissions series)

Air Corrector: 150

Emulsion tube: 7772.11

Main jet: 130 (probably needs to be 135 or so. Gets a little lean on high RPM)

Engine: SOHC 1300cc head worked with larger valves and mystery cam

1 1/2″ headers, 4 into 1 exhaust, 3″ secondary, high flow muffler

At the moment, got 35 degree of advance dialled in. The dizzy-less Megajolt ignition system is currently being perused as an alternative.

Industrial espionage is probably not an issue for 30 year old technology. If anyone has thoughts or comments on these figures, we’d love to hear from you.

New Lid

February 14, 2010

Spent another arvo in the shed, and came up with some good results.

We’ve decided to ditch the Arbath style bootlid. It weighed about 10kg, and somebody once claimed that cutting 5 kg was equivilent to adding 1 horsepower. Rough rule of thumb I know, but 2 extra horses never go astray. The back half of the boot will be a fibreglass version of the normal bootlid. This will also allow the engine bay to stay a hell of a lot cooler. We’re going to try and get some glass wrap for the headers to keep the carbies cooler as well.

Al mesh and Al frame

Julian has tracked down some bits to put together a sensor array to log useful (useless) data. A bunch of small solid state temperature sensors and a milspec potentiometer which will be used as a throttle position sensor. He’s planning on passing the sensors through an ardwino and into a palmtop computer. I’m sure he’ll write more about it as it comes together. It’s good to be doing things that aren’t going to put the car on block for months if they all go pear shaped.

Next week is the FIAT Car Club of Victoria Concourse. We plan on attending with Bianca in tow, so come and say hi. It’s always nice to meet a fan…

Research, then trial and error.

Research was teh crucial part, and the reason why it has taken us nearly a year to progress to the point where the car will start and idle successfully. I haven’t written on this blog for many months because it has been just too embarrassingly disheartening. For a while I lost faith, thought we’d spent too much on some crappy leaky sidedrafts which didn’t bloody work. Research shed some light. Here’s the saga as it unfolded.

Synch Carbs

Juice Synching Carbs

Possibly as far back as 12 months ago, some reading on Guy Croft’s excellent forum turned up the holy grail of 40mm Weber sidedraft jetting for our particular application. Some careful fudging of these figures to allow for a smaller displacement went on in Julian’s head, and we came up with a theoretically perfect jet combination. The carbs were already rebuilt, the world’s sexiest airbox was welded up so all that was left was to insert textbook jets and race.

Not quite.

To cut a year-long story short, we found out that there are many different series of Dellorto DHLA carburetors (See this article, possibly originating from the Sideways Technologies forum). Our particular ones came off an Alfa, so were probably emissions, meaning that the progression circuit was designed to meet the US emissions laws, and thus less tunable than earlier non-emissions (and most Weber) carbs. Thus the textbook idle jets we forked out for were way too lean (we’d planned on 47, currently running 60) and air correctors were too small (details to follow soon!).

The Interrogator

Pross, 'The Interrogator'

This much we now knew, so we booked in to see Pross at Enhanced Motorworks in Fairfield. After 5 or so dyno runs, and a consultation by a talking computer called the Interrogator, we had eliminated the lean idle, synch’d the throats, discovered the rich spots and dialed the advance. It took a morning, but Bianca is finally dialled for race. The final figure was about 60kW / 80 HP at the wheels. I guesstimate that the whole package weighs less than 800 kg wringing wet, which brings us close to 100HP/ton. I’m off to the Alfa club website to book us in for 14 March. Watch this space!

P.S. Thanks go to Woppy for his thoughts on why it wouldn’t hold idle, and Peter at Thornbury Carbureters for being so conveniently located.