Last week we covered the installation into Frank-the-EF-Falcon of the new Jim
Mock Motorsport cam, new hydraulic lash adjusters (HLAs), new valve springs and
a new adjustable camshaft drive gear. However, when the engine was started, it
was found that one of the 160,000km old plastic timing chain guides had broken.
Replacing the guides involves removing the electric radiator fans (to create
sufficient room), removing the crankshaft damper, removing the serpentine belt
idler pulley and tensioner assembly, removing the timing chain cover and
dropping the sump. And with that much work, it makes sense to also replace the
timing chain and all the plastic chain guides.
Since, strictly speaking, this isn’t normally associated with a cam
installation, we won’t cover it in step by step pics – rather, we’ll use some
general shots to show what happened.
New Timing Chain and Guides
The sumps bolts were loosened to allow the sump to drop down. Later, the
subframe also needed to be dropped, so that the sump could come down even
further. The reason? The lower plastic chain guide, which normally is a tightish
push-fit inside the timing chain cover, fell straight down into the sump when
the timing cover was removed. (Presumably, it had gone loose over time.) To
retrieve it, access to the sump had to be improved.
When the serpentine belt tensioner assembly was removed and inspected, the
two idler pulleys proved to have worn bearings – when spun, the bearings made a
‘gritty’ noise. Aaagghh, more expense! The cost is normally high as the
pulleys can’t be bought separately from Ford – you need to buy the whole
assembly.
However, mechanic Simon has a fix for this. Rather than use Ford stuff, he
uses two pulleys designed to suit Holdens. As shown here, the grooved pulley
normally fits an 6/1999- LS1 Gen III engine, while the flat pulley is normally
for a VT-VY V6 Commodore. The replacement pulleys aren’t an exact
match...
....the flat pulley is a little wider....
... and the grooved pulley a little smaller, but they work fine in the
application. And at a much lower cost than the complete Ford replacement
item!
One of the three plastic timing chain guides can be seen here. Putting the
guides (and the chain) into place is quite quick and easy – the time is spent in
getting access to them.
A new front crankshaft seal was installed...
...and then a bead of sealant could be run around the timing cover and the
cover installed.
So now we were back to where we’d been quite a few hours and many hundreds of
dollars previously! To reiterate: expect the unexpected when working on an older
car. Of course, we could have just replaced the timing chain guides and
not installed a full timing chain kit, and we could have kept the
original HLAs and valve stem seals – but that would have been false economy. The
timing chain, valve stem seals and HLAs should now be good for another
150,000-odd kilometres.
Dialling-In the Cam
The instruction sheet provided with the JMM Streetfighter cam says that the
cam timing should be adjusted (the company provides an adjustable cam gear with
the kit, remember) so that at Top Dead Centre on No 1 piston, the inlet valve
has opened by 0.042 inches, as measured by a dial indicator located in line with
the valve, touching the oil hole in No 1 rocker.
This shows the set-up. Simon made a steel mount (red arrow) to hold the dial
indicator gauge (green arrow) in the correct position so that its sensing
plunger was in contact with the rocker over the top of No 1 intake valve (purple
arrow). The crankshaft was rotated until the cam was on its base circle (ie
opposite the lobe) for No 1 intake valve, with the intake valve about to
start opening. The dial indicator was then zero’d. The crank was then slowly
rotated until the intake valve began to open, and the opening distance measured
when Top Dead Centre was reached (as shown by the crankshaft timing mark). It
all sounds complex – and it’s important to get it right - but in actual fact
it’s quite easy.
And what if the opening of the intake valve is not 42 thou at TDC?
Then it’s a case of loosening the bolts on the cam sprocket and rotating the cam
slightly with regard to the crankshaft position. And then repeating the
measurement process...
When the measurement is correct, locking compound can be applied to the cam
sprocket adjustment bolts and the assembly tightened so that it cannot move
further.
But here’s the big question: is a cam positioning that gives 42 thou
lift in fact best? The answer to that question depends on a host of
factors including the individual engine characteristics (eg the actual
compression ratio), the intake and exhaust modifications, and most of all, what
the driver actually wants. Traditionally, advancing the cam gives more
bottom-end at the expense of the top-end. On a street driven engine that can be
a good thing, as the engine spends vastly more time at lower rpm than higher
revs. In fact, on that basis, we set the cam timing to give 49 thou lift (1.25mm
– we were using a metric dial indicator), an option suggested by JMM for more
low-down performance.
Driving!
Much to our surprise, the engine started and ran fine with the Streetfighter
cam dialled-in at 49 thou lift – and with dead standard engine management! In
fact, we were able to drive home from the workshop with the car in that
configuration. It idled fine, had excellent tractability and a decent (though
not overwhelming) top end. However, when we put the MoTeC air/fuel ratio meter
up the tail-pipe, the LCD showed that at idle the Falcon was running super-rich
– about 12.5:1. This richness was in part caused by the use by the standard
management of a MAP sensor. Manifold vacuum is lower at idle than with the
stock cam so the ECU thinks that the load is higher than it really is, so
injecting more fuel.
Rather than continuing to drive the car in this form, we plugged the
ChipTorque off-the-shelf chip into the ECU. (This is the generic chip designed
to suit a Falcon six with a warm cam.) However, being able to just plug the chip
in was the result of work previously undertaken.
The ECU had been removed and the outer cover taken off.
Contacts for the new plug-in chip are already present but they must be
thoroughly scraped and cleaned before....
...they are tinned with solder. The ECU was then reassembled and placed back
into the car, awaiting its new plug-in chip.
With the ChipTorque chip in place, the idle air/fuel ratio returned to
standard. The car also had a noticeably sharper mid-range throttle response but
at full load, was running a bit lean (about 13 – 13.5:1). However, a very
interesting trait was noticeable. At 100 km/h cruising speed, the car smoothly
drifted along on the smallest of throttle openings, while the MoTeC air/fuel
ratio read numbers as lean as 17:1! (That’s much leaner than the 14.7:1 that
would normally be occurring in those conditions.)
But cut to the chase: what was the power like?
Well, the top-end was much the same as before – the 0-100 km/h time was the same 7.5 seconds previously recorded after the intake and
extractors/exhaust had been done. The mid-range also seemed little changed, but the extreme bottom-end (eg below 2000 rpm) was better than ever. How much better? Enough to be able to keep up with normal traffic –
changing gear at about 1700 rpm!
To be honest, this put us in a real quandary. Despite popular opinion, on a
road car it’s better to have another 5kW at 1500 rpm than 10kW at 5500 rpm –
it’s simply much more useful. But then again, if you want to go faster, more
power is better! So should we leave the cam timing as it was and simply optimise
the electronic tune (fuel and ignition timing) on the dyno? Given the lean-ness
at the top end, with a real-time tune you’d expect to gain some power up there.
Or should we go back to the JMM-recommended 42 thou lift cam timing setting, and
expect to get a fair bit more top-end?
(The option of sitting on the dyno for a day, trying lots of different cam
timings and then real-time tuning the fuel and ignition timing to suit was
simply too expensive.)
After talking to both JMM and ChipTorque, we decided to carry out a test. To
many people, that test will appear from left-field – it was for economy! In
short, if the 17:1 air/fuel ratio at 100 km/h cruise and the 49 thou cam timing
gave noticeably improved fuel economy over standard, we’d be very tempted to
leave the cam timing where it was. But if the fuel economy was not dramatically
better, the benefits of leaving the cam timing as it was were diminished.
Previously, when cruising along the Brisbane – Gold Coast motorway at the
speed limit we’d achieved an indicated average of 7.5 litres/100 km. (Yes, very
good indeed for this size of car.) And with the cam set to 49 thou timing and
the off the shelf ChipTorque chip in place, well, - wait for it – the fuel
economy was exactly the same.... 7.5 litres/100km!
That suggested we should retard the cam timing and go for a bigger
top-end.
We’ll find out what happened next week.
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Simon was paid at normal rates
The camshaft was supplied by Jim Mock Motorsport at commercial rates
The chip was supplied by ChipTorque free of charge
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