Frank's Cam Part 1

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.

Before installation, this Permatex engine assembly lubricant was liberally used on the HLAs, cam lobes and cam bearings.

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.

Contacts: www.jimmockmotorsport.com www.chiptorque.com.au Simon’s Car Clinic - 07 5543 6155

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