Head gaskets will solve the problem, but I'd suggest you forget going into your engine unless you have to.
Consensus says alloy heads with XF style chambers a detonation prone. So are any massively shaved stock heads from 1976 to 1993.
The best bet is to advance it back up to 40 degrees, add the vaccum advance, and run water injection.
If you have a post XE head, then there is a cutout in each intake port where the gasket sits. Any Falcon XD-to XF can take a massive 12 mm spacer, which can fit nitrous and water injection. I've made a few before, but have never had an engine that detonates becaseu I used to use Propane.
A performance engine is detonation limited. Lowering compression is against efficiency. A water injection unit can run off the blue Bosch MAP sensor used on EST Falcons. It is a poteniometer which can operate as a switch at a given vacum. It should be set up to add water at the votage which is equivalent to 3" Hg or vacuum. This can be done by a simple electronic circuit. As soon as the voltage drops, the water injection circuit triggers the humble Cortina screen washer bottle. Add six brass 1/8 bsp blanks with one 15 thou hole, angle drilled as per the bosche injector and run it off the stock hose.
There is 45 psi to be had, and it totally eliminates knock under wide open throttle. Nada, none, nil, nothing. It won't fail you as the normal Cortina unit uses two squirters with 20 thou holes, so it will operate under less pressure.
When the engine starts, the vacuum will drop, and water will pore in via the winscreen washer, so there must be a 5 second power dealy relay to avoid that happening.
As for bull crappers who say water injection is a crock, let them spend money on high octane, mechanical advance dissys which loose enoght part throttle economy to make you wish you had a V8, and to other gear which solves problems for a bigger cash outlay.
At high revs, the water injection will drop power, but it won't pop pistons, gaskets, or cause crank bearing and cam failure. If you want power gains as well, get a spare washer bottle and water pump as a standby, and add 600 mls of methanol to each 600 ml of water, and two teaspoons of PVC pipe acetone. Taht will allow a lot of advance.
Thirdly, there is a piezo electric knock sensor on the last XF Falcons, which bolts to the front battery terminal on front right. It retards the spark on EST engines. That can be used as a trigger for water injection.
The systems are there, they just need to be used.
My experience with H20 injection is from a 4080 pound Pontiac Formula 454, which ran 46 degress advanace, did 13.6 second quarters at 100 mph, and ran stock cast pistons and a Quadrajet 800 cfm carb. No detonation, no avagas, no problems. Another guy ran a homebuilt system on his Cortina 2000, chronic detonation was eliminated.
Deano
).
