Improvements and modifications are made to the Cortina.
As long as they don't give proved results,
they're more like experiments.

The rear end seemed a bit too low, as the exhaust dragged on the asphalt in the corners. The pinion angle was also a bit off, so the lowering blocks were angle cut to improve things. The drivers side lowering block was cut a bit more, in effect making this side higher, to compensate for the weight of the driver. The rear spring is already a bit harder on the drivers side for the same reason, but the balance was still a bit off.
The lowering block outlined in black in this pic.
(May 26 2013)

As the spark plugs looked like the engine runs way too lean some carburetor tuning has to be done.
To aid in this work, an Air/Fuel ratio gauge was acquired along with an O2 Sensor.
The exhaust pipe already had a sensor bung welded in, but it pointed downwards, so a piece of exhaust tubing was cut off, turned around and welded back in.
As this work was done, the exhaust pipe was mounted as high as possible.

This is what the O2 sensor off of a junked VW Polo looks like, and the Air/Fuel gauge.
The gauge is very simple, but calibrated with a good Voltmeter, it should work.
The idea is to be able to determine if the carb jet changes affect the Air/Fuel ratio at full throttle accelleration, full speed or part throttle, and so forth.

The image to the left illustrates the wiring of the Zirconia type oxygen sensor. It's a heated model, so the two white heater wires go to + when ignition is on, and to ground respectively.
The black signal wire goes to the (in this case) green signal input lead on the A/F gauge. The red and black wires coming from the gauge are for illumination (red) and ground (black).

The cheapo oxygen gauge didn't work at all, but testdriving with a multimeter connected to the oxygen sensor told us what we needed to know.
Smaller air jets and bigger main jets improved the way the engine ran, but the A/F ratio was too rich at low revs. Next we'll be back to the first main jets, and even smaller air jets. Just had to order them.


The engine emitted an alarming amount of smoke from the crank case, so
it was deemed necessary to take a look at the internals.
First the cylinderhead came off and it was sent to BN Motor
for a thorough check and some improvement to the combustion chambers.

The cylinder head came off first and revealed a few small scratches in the cylinder walls. Nothing some honing couldn't remedy.
Everything looks good so far.
(June 7 2013)

The exhaust header looks sad to say the least. What's worse is the way the collector pipe is welded to the exhaust joint. A hole burned with a mig welder, and there's a huge drollop of material inside the pipe.
Also the primaries need to be ground on the insides.

When the pistons came out, a piece fell off of one of them.
Luckily a piston in usable condition was found at a friendly racer's garage, he actually sent three pistons so we could chose a good one.

The pistons cleaned up, new rings mounted and ready to go into the engine.
The "new" piston was lightened a few grams to the same weight as the others.
(June 22 2013)

The oil pan was modified with some splash plates.
The oil dip stick goes into the hole in the front of the pan.

New bearings have been mounted and the bearing caps torqued after the bearing clearances have been measured with plastigauge.
At .002" they are spot on.

The oil pan is painted with rattle can black and mounted to the engine block. So are the oil- and water pumps
Now the engine's ready to go back into the car.
(June 23 2013)

The "three Y" exhaust header got a new coupling between the collector at the last Y and the bigger exhaustpipe. And a heat resistant black paint job.
(July 2 2013)

The engine is back where it belongs, but is still missing carbs, exhaust, valve covers and a few other parts.

The start up and test drive was a success in itself, but the engine didn't run very good, as the distributor's not cooperating. The old one has to go back in.
Now it's time to re-torque the head bolts and adjust the rocker clearances again.
(July 3 2013)

Introduction,   Body work,   Details,   Tech,   On the track 2013   Experiments and modifications
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