Somewhere down the line we have to face what we don't want to hear. The economical and excellent ADM 34 Carb is just too darn small. There is no meat to take it aout any more than 31 and 30 mm in the throats, and the gains level out before 200 hp. The lead plugs will need to be taken out, the jets, emulsion tubes and idle corrector will need to be changed.
If there were enough Weber ADM experts around, I'd be doing that right way. There aren't, though.
I strongly suggest keeping all emission gear, the stock air cleaner, or one from a TBI EA Falcon, and fit it up to the V8's 5 1/8" neck. The stock emissions gear is there to warm up the engine fast, and I see no reason why you cant use it. With the right electric choke, spacers to shift the carb out further, and a vent for the carby back to the evaporative emmissions, then you could get a 500 Holley on it, and get it past the emissions guys.
There are K&N filters, good XF cool air intakes, and some very good, cheap parts around for it.
The intake mainfold is slightly restrictive, but very good. I have ground out one of these easily, and it is very economical, still can run the EGR, and is able to pass any inspection.
Up to about the 210 mark, it should be a piece of wees to get your smog six running harder than a stock 351 V8, without the fuel bills. The secrete is jets, power valve and getting the basics right.
Forget this "lets rip off this emissions crap" BS, and make the thing breath warm air until its warmed up, and then cool air like the factory intended once its up to temp.
As for the compression, its way too high. You'll have to run a Holley/ Speco Thomas or Edlebrock Water injection system to kill the detonation using the MAP sensor most XF's had. The ignition is to agressive to cope with 11:1 with even 98 octane. You have to settle on 9.5:1 max, or spend another 300 ping on ensuring the thing doesn't blow. There isn't enough head gasket or clamping pressure to cope with detonation, and it will take the bearings or even No 5 piston out without too much effort.
