After modifying the intake system (series starts at
Negative Boost Revisited, Part 1) and fitting extractors
and an exhaust (Frank's Exhaust, Part 1), the next step was to
fit a new cam. However, what was intended to be just a relatively low cost job
turned out to hit the hip wallet far harder than expected...
Cam Selection
As with the extractors, we sourced the cam from Melbourne’s Jim Mock
Motorsport. Over the years, JMM has put a lot of work into Falcon six cylinder
cams, not in chasing just outright power but also in terms of idle quality and
mid-range torque. We told the company what sort of car we were after and they
supplied their ‘Streetfighter’ cam, which is also fitted in their Dev 4 kit
upgrade. Including valve springs and an adjustable cam gear, cost was $920.
The cam is suitable for the standard head and compression ratio, but needs
(supplied) replacement valve springs and (not supplied) engine management
changes. For the latter we decided to take a two-pronged approach. First up,
Gold Coast’s ChipTorque supplied one of their off-the-shelf chips to suit a
Falcon six running a warm cam. That would get us started. Then, when we’d driven
the combination of the Streetfighter and off-the-shelf chip and could identify
areas of the tune we wanted changed, ChipTorque would real-time dyno tune the
car.
In addition to the camshaft, JMM supplied the new (inner and outer) valve
springs, shims to fit under the hydraulic lash adjusters (HLAs) to take into
account the smaller cam base circle, and an adjustable cam gear that would allow
the cam to be retarded or advanced to match either JMM spec or personal
preferences.
Cam Installation
We booked our local mechanic (Simon’s Car Clinic near Tamborine Village,
Queensland) who suggested that the installation of a cam would take only a few
hours of labour. But then when we arrived with the adjustable cam gear (so the
cam would need to be dialled-in – more time) and the new valve springs (so the
old valve springs would need to be removed with the head still in situ – a
lot more time) the predicted labour time about doubled. So if you’re not
doing this work yourself, it’s important to thoroughly describe to the mechanic
the job that you want done.
It’s also very important to have a contingency fund in case the bill rises
still further. In our case, there proved to be some major unforseen expenses –
and that’s quite likely to be the case when working on any car that’s over a
decade old.
Cam Step by Step
Simon took off the new intake system...
... removed the sparkplug leads...
..removed some hoses and undid some bolts before he was able to lift the cam
cover clear.
He was then able to remove the sparkplugs...
...before undoing the bolt holding the cam gear in place.
The many bolts holding the valve-train in place could then be
undone...
...before all the rocker gear could be removed as one assembly.
With all the valve-train on the bench, the hydraulic lash adjusters (HLAs)
were removed with a pin-punch and a hammer. The HLAs are easily pushed out in
this way – they aren’t a tight fit.
Because of the changed cam base circle diameter, shims (just washers are
supplied) are placed under the HLAs. To help determine how many are needed under
each HLA, the new cam is temporarily installed and the valve-gear placed back on
top. The number of washers that then make for a tight fit (as in, tight enough
to cause 0.030 – 0.050" compression) between the cam base circle and the HLA is
then ascertained. In our case, two washers were placed under each
HLA.
New HLAs were lubricated....
...and then fitted. New HLAs were installed because on cold start there had
been an occasional ticking from a sticky lifter. The extra labour costs is zero
(the original HLAs have to be removed to allow placement of the shims) and
putting in new ones means there’s one less thing to worry about.
With the HLAs and shims organised, the old cam could be
removed...
...the new cam thoroughly cleaned of its protective film...
...and then lubricated and placed in position.
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Before installation, this Permatex engine assembly lubricant was liberally
used on the HLAs, cam lobes and cam bearings.
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Before the cam could be installed, the adjustable cam gear was
zero’d and the adjustment bolts tightened...
...before the old cam gear was threaded past the chain and the new one slipped
into place.
Simon was hoping that the new cam gear would be able to be placed onto the
nose of the cam without releasing the hydraulic/mechanical chain tensioner
(arrowed), but this was not to be so the tension was unscrewed to give
sufficient chain slackness.
The next step was to pressurise a cylinder with compressed air, so holding
the valves in place. This allows the valve springs to be removed without taking
the head off.
A valve spring compressor was used to (duh!) compress the
spring....
...before the retaining collets could be withdrawn by a magnet.
A comparison of the old and new springs shows the greater preload (and so
seat pressure) provided by the new longer springs.
While the valves were off it makes sense as preventative maintenance to
replace all the valve stem seals. These have their circumferential springs
removed before they are pressed on with an appropriate drift and
hammer...
...and then the springs slipped back on.
The valve-gear (complete with new HLAs and the shims) could then be replaced
and the rest of the engine bits reassembled.
All looked good and the engine was started (the dialling-in of the cam still
to come) but the timing chain was making an odd noise. Like, odd enough for the
cam cover to come straight back off. And that showed that one of the 160,000km
old plastic chain guides had broken, allowing the chain to slop around. Sounds
easy to replace it, but in fact that the timing chain cover has to then come
off. And to get that off, the radiator fans need to come out and the sump needs
to be dropped (the sump interlocks over a lip in the lower part of the timing
cover). And if you’re going to that much trouble, you may as well fit a full
timing chain kit that includes the three plastic guides and a new chain....
Next week, we’ll do that as well as dialling-in the cam.
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Simon was paid at commercial 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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