Date of Publication: 9th July 2003
* Pricing and Conditions in Article Updated.

Text and Images taken from Street Machine FORDS.
Reference: Street Machine FORDS Issue 1 2003 (Pages 114-117)
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THE POWER churning out of the supercharged EB Falcon from Jim Mock Motorsport (JMM) at Easternats impressed the hell out of us, so we took a closer look at what these guys are about. Jim Mock and his son Brendan have delighted six cylinder Ford fans by burning the midnight oil over the past couple of years working out how to pull more needies from the 3.9/4.0-litre (EA-AU) six. While JMM's supercharged EB did make 237kW at the rear wheels, it was their normally aspirated DEV upgrade kits for the 4.0-litre that tweaked our interest.

JMM offers eight upgrade kits for the 4.0-litre, and they'll ramp power to 112kW for a start, all the way past 200kW with the top kit, all at the rear wheels. A stock non-VCT XR6 is good for around 110kW at the wheels, so even the DEV-1 package will give you a noticeable seat-of-the-pants kick.

1® To optimise can timing, JMM supplies these adjustable timing gears

2® The factory two-peice valves are pretty good, but JMM opts for one-peice stainless valves for all-out performance work

3® XR8 snorkles are good things - the custom filter also helps. The TE50 version is popular but incorrect fitting can reduce performance. The snorkel for each model is very carefully matched to the shape of the body and bonnet. Fitting the wrong one for your body style messes up the relationship. JMM will put you on the right track as to which one to use

All kits except the DEV-6 incorporate the same 3-2-1 Tri-Y-style extractors. After much testing, JMM settled on a small diameter primary, as this proved optimum for scavenging the combustion chamber - essential for good emissions. From there, the exhaust system is 2½-inch mandrel pipe with a high-flow cat and two straight-through mufflers.

At the start of development, JMM played with a host of different cams, and now has a wide selection of preferred grinds to suit different applications. However, cams alone weren't going to provide the performance increases they were looking for. Thus head work moved to the top of the list for the DEV-4 (165kW) and above kits.

The first priority was bigger ports, along with a bit of subtle reshaping. Then the chambers got some attention. Basically, JMM would test an engine, pull it apart, and check the burn patterns on everything. Alterations were made wherever there hadn't been much combustion activity, until they achieved even colour right across the chambers and crowns.

After investing so much time in developing what it considers to be the ideal head configuration, JMM keeps quiet about the secrets behind many of its modifications. One detail Jim did reveal is that they get rid of the factory 'humps' in the chambers.

If you have the option, the plain EF or early EL head is the best starting point for most performance applications. However, all of the heads can be modified for similar power outputs.

4® The sides of the chambers are laid back considerably. General re-shrouding covers much of what's been done but there are other subtleties involved. This is a standard chamber with the modified versions at the back

5® EB-ED heads are marked with the model year followed by AA. Tickford versions have a T. EF-EL heads are marked with the model year followed by DA. Tickford units of this era have the T and the model year followed by DT. Anything that begins with WR or 1R is an AU head. On Tickford AU heads, the WR is followed by a T. Also, the number ends in AC for standard heads while Tickford units end with AB. LPG heads have a green daub of paint and are stamped L.

USING THE RIGHT SPARK PLUGS IS
LIKE ADDING
A COUPLE OF EXTRA
DEGREES OF TIMING

While the cam and valvetrain is unique to each head, the entire head assembly from any of the models is interchangeable between blocks.

Valves in early heads have 11/32-inch valve stems, whereas the AU has smaller 7mm stems controlled by tapered springs. Those tapered springs can't cope with high-lift lobes, so JMM developed special retainers that hold the thinner stems but allow the fitment of larger-diameter performance springs.

THE FACTORY COMPUTER SUPPLIES A LOT OF FUEL, SO INCREASING THE AIRFLOW TO MATCH IT
IS ALL THEY'VE HAD TO DO

7® If number one cylinder isn't at TDC when the head is mounted, the valves will hit the pistons on start-up and break the rocker arms at the tips.

8® Most of the big power gains lie in working the head. Standard inlets in front, modified versions at the back. JMM didn't want us to show too much of its port and chamber secrets.

9® The company is getting good results with triple-layer metal gaskets, resulting in a compression ratio of up to 9.6:1 (up from 8.3-9.1) and requires the exclusive use of premium unleaded.

10® This is the production EA casting. You can clearly see the substantial protrusion between the inlet and exhaust. It is the largest of all the heads

Brendan says they really like hypereutectic ACL pistons. They are extremely strong, well oiled, tapered pins, with bigger valve reliefs than most and are a touch lighter. Additionally, their 5cc and 11cc dish offers good scope for adjusting compression.

After trying all sorts of spark plugs (all of which caused detonation), JMM finally settled on a particular Autolite plug. Originally these plugs were shipped to them by mistake and, as it happened, they worked! Screwing them in saw an instant 4kW gain. According to Brendan, "using the right plugs is like adding a couple of extra degrees of timing without actually doing it."

Low-impedance leads are also important, with JMM exclusively using a Champion version.

11® Here's the broadband (snail shell) inlet manifold split in half. With the butterflies closed, the manifold is a longer runner-style as the incoming air must go all the way around the loop (snail shell). This is done to improve low-end torque. As revs rise, top end power is improved by opening the butterflies allowing the air to bypass the snail shell section dramatically reducing runner length. It's a good thing and can be retrofitted to the earlier EA-ED engines, but re-tuning is needed on these engines to regain correct fuel and spark. Except a 10-22kW gain by adopting this newer manifold and the accompanying cam.

12® While they don't look very fancy, JMM has found that Tri-Y, 3-2-1 extractors work best. All their kits, bar the DEV-6, use these same headers.

13® Ford introduced the snail shell-like, two-peice, dual-runner-length, broadband inlet manifold in the EF ('94) Falcon. This inlet has distinct advantages for low- to mid-range power (up to 4000rpm), without being overly restrictive to top-end capability.

Crank wise, JMM feels the AU unit is the best for big power upgrades, as it's made from a stronger material and benefits from larger balance weights. Brendan says the AU engine has no harmonics and revs out better, and the main caps are larger and wider. The AU's stud girdle, in combination with the cast alloy sump helps hold things together.

Oddly enough, all but the DEV-6 packages acheive their rated power using stock ECU programming, as retaining idle and emissions was important. Only the VCT-equipped models require the addition of a Unichip. Turbo or supercharging applications will require an aftermarket engine management system (ECU).

® HOW MUCH ARE THEY?
ALL quoted prices are for supplied, fitted, dyno-tuned and fully tested kits - an all-up price. Additionally, all quoted power figures are rear-wheel outputs and represent the minimum gains expected. Many of the above kits will yield considerably more power - depending on the spec of the base engine and its condition. JMM feels the DEV-3HL is the best value for money, as it doesnt involve any labour-intensive headwork.
DEV-1 112kW $1,290
DEV-2 125kW $1,590
DEV-3 134kW $2,725
DEV-3HL 146kW $2,990
DEV-4 160kW $4,990
DEV-5 170kW $5,790
DEV-5a 175kW+ $7,350
DEV-6 185kW+ Call

According to Brendan, the factory computer supplies a lot of fuel, so increasing the airflow to match it is all they've had to do for some of their kits. However JMM does admit to cheating a little bit on the heavy-breathing DEV-4 and above kits by using a higher-pressure fuel regulator to force more fuel through the stock injectors to gain the extra fuel required.

Whether your EA-AU six cylinder Falcon needs more poke, or you want an ultra stout six for the
off-roader or race car, JMM has what you need. Give Jim or Brendan a call (03 9399 4401) for the good oil.
® BLOWN SILLY
OFF COURSE, what you really want to know all about is the supercharged, intercooled, four-litre EB. The prototype kit has already made 237kW at the wheels with 5.5lb boost and a lot more to come once the boost is turned up on the Powerdyne centrifugal supercharger. While the crew was quite secret about its make-up, they did reveal its a hybrid of all the best factory parts based around an AU block, an EF head and Hawk EC-12 ECU. Maybe they'll give us an inside look in the not too distant future.