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Frank's Cam Part 2

Results of the first cam timing setting and plug-in chip

by Julian Edgar

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At a glance...

  • New timing chain and guides
  • Dialling-in the cam
  • Decisions, decisions - cam timing, air/fuel ratios...
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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.

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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.

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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...

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....the flat pulley is a little wider....

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... 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!

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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.

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A new front crankshaft seal was installed...

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...and then a bead of sealant could be run around the timing cover and the cover installed.

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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.

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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.

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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...

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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.


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.

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The ECU had been removed and the outer cover taken off.

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Contacts for the new plug-in chip are already present but they must be thoroughly scraped and cleaned before....

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...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.


Simon’s Car Clinic - 07 5543 6155

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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