Head Work


Well-known member
Hi i have a XC falcon with a 4.1 x-flow and i want to swap to an alloy head, but have a few questions.

Which is the best casting to use ?

What porting can be done ?

How much can the head be decked ?

What size are the combustion chambers ?

The car is my daily driver and it must be able to run on ULP, any help would be appreciated. thanks.
I'd suggest look for a late XE ULP head (others may disagree), also get the XE ignition. Disco may offer the CC's for the head. The heads already flow well. Dig up MarkZE or Joel Smith to ask what they think for porting.

You may well need a "conversion gasket set". Check with "alloydave". Unless you have dual pattern extractors, you'll need new ones of them (or a new cast manifold).

Regards, Adam.
Gidday 2nd gunman,
If your using your old block from the cast head engine im not 100% on the change over to alloy but from memory you will have to change a few of the water galleries and the dowl on your block.If your going to run on
91 oct i wouldnt plane the head to much ,just enough to ensure straightness and surface finish.a hardness test is agood idea if your getting a alloy head as they can go soft over time.unfortunatley combustion chamber size and design is something i dont know,apart from some basic
shapes and valve sizes.im using a xe efi head on my 250 with a holley
500 2 barrel (or 465 4 barrell when its fixed).id had a mild port job done
with a 3 angle valvegrind on the intake.you will need a different intake &
exhaust manifold if you pick a efi head.the late xf had large intake valves .id pick one of those if i did it again. follow up a the guys addo
suggested for some good porting advice..
use the head gasket set suited to the head style you choose.
cheer dave 67xr6
ps..welcome aboard
Is there much gain from the XE ignition? is it electric and what parts do i need to do the conversion?
The XE ignition needs an XE distributor (obviously!), XE coil or Bosch GT40 coil or Accel/Mallory/Echlin copy of... good leads too. About $60 for the XE parts at a Sydney wrecker.

You might need to redrill and tap the mounting hole for the hold-down bolt. When you look at the XE unit, it's obvious why.

Also have to make up a new thick wire to bypass the resistor wire. It plugs (male bullet connector) in at the loom under the bonnet, near the brake booster, and you carry the new one all the way to the "+" on the coil (eye connector). That's your install done. Open the plug gaps to 50-60 thou and enjoy! Try not putting the boot in and you will save fuel (hard to, though :eek: ).

You can enjoy this way before any head change. A cam change will also give more fun. At the very least, expect the timing set to need renewing.

As far as porting goes, there is plenty that can be done but there is an art to doing it. There is not a huge amount of material that needs to be removed. It needs to be removed from the right places and by a person who knows how to remove it.

Standard EFI valves are good for

inlet about 230cfm @ 25 inches
exhaust about 160 cfm @ 25 inches

This is about 370hp using superflows hp calculations.

Find a cylinder head guru who has done ford six heads beofre and who flow benches them and can give you real figures.

I also suggest using the late EFI heads from the XF falcons.

CC's for the chambers vary around the 50cc mark.

The psitons dishes vary a lot also, so the amount you should deck the head depends on a number of factors.

I would suggest ripping the head off and measuring the deck heights and piston dish before you deck the new head. About 10:1 maybe 10.5:1 is the most you want to run in a street engine on BP ultimate fuel.

You will need to dowell the block also to suit the alloy head. I suppose you could probably leave the dowels out, but I wouldn't.

The alloy head needs different inlet manifold and different exhaust manfolds too.

I would suggest getting a whole XF engine cheap and building it up from scratch with decent ACL pistons and 200 crossflow long rods.
what exactly do u need to do with the dowels?

i have heard that XF carb head is a direct swap for the iron head, but that the EFI head was slightly different is this correct? also which is better?
If your running are carby XD/XE/XF alloy head:-

Blue print cc for XD to XE alloy head was 53cc at the chamber. The later head needs to have the later ignition, so you can service it without taking the carby manifold of. My friends who have used stock non transitorised XC/XD cast iron head igniton always get problems here.

The block for alloy head falcons has an 80 prefix, meaning its been minted in 1980. So the best option is grabing an old XE head gasket, and slapping it on a spare XC block. Got mates who have Ford 4.1 cast iron junk in there yard...or friendly wreckers?

There will be some emission issues if you use the XF stuff. Like, do you want to run all the electronic controls, or just pike out for the easier XE set up. I favor the XE head because it uses less electronics, but the high swirl XF head is technically better because it produces more power and better economy in an XF than an XE.

Ex Repco and Ford Special Vehicles man Bill Santuccione says (in a 1990 Street Machine article) catagorically the XF head is to be avoided because it is "detonation prone".
so if i got a xc head gasket and a xe head gasket i should be able to see the differences? also is it just a matter of pulling out the dowels and punching them into different holes or do i have to drill new holes?

i cannot pull the head to have a look as the car is my daily driver.
I know diddly about the dowel. I guess its there because of the different expansion rates of steel and alloy. Dunno.

First, get biffed old cast iron x-flow and newer alloy head gaskets, pay no money for 'em.

Then you gotta find a compliant wrecker or buddy who has an old redundant XC/XD cast iron head Ford in his yard. Ask around, and be a pain in the butt until you get to see one of those blocks with the head off.

Logistics is the killer. Or wait out for a while for us to get our info sorted. You on the winning team here. Theze in-liners are not often stuck for info. A Dutch dude is working on a load of info for Addo at the moment, and he doesn't even have a Falcon.
2nd-gunman, you touched on an important aspect there. If the car is your daily driver, and you're not mechanically experienced with it, holding back is advised.

Your best bet really is the swap-in approach. This will be quicker in execution, and a safer policy as you've had time to address any other pertinent issues. Look, I don't want to sound like a wowser, but this is going to run close on a grand if you do it right... Figure $120 for a timing set, $85 for the gaskets, $180 for the new motor (as is), $500 to scrub up the head and do light portwork; the rest on a quick in/out at the local workshop.

Sorry if this sounds like something you didn't want to hear, but I'm saying it to try to keep you running as smoothly as possible.

Regards, Adam.
i don't want to swap ion a whole new engine as the engine in the car is a stock replacement engine from GEM that is only 20,000kms old. It is in top condition and just needs more power.

I do know my way around an engine having done plenty of work on my V8's and my mates X-flows but having never performed this swap before i want to make sure i have researched it completely before i pull the head for the swap.

the other problem is between all te other work i have going on i don't have time to completely rebuild an engine or the money.
Can I make a suggestion here?
If this engine is a recent rebuild, do a compression test. This is not always accurate but will be enough for this.
If the engine is a rebuild and is in very good condition. Why not just slip in a better cam and new lifter set?
That would be a good weekends work and would generally improve the cast iron headed engines power considerably.
Still keeping the single barrel stromberg for the start. But make sure all the tune up is spot on. No problems with the air cleaner or that gas crap if you are running on that lpg rubbish. A few people that I know has fitted better cams to the XC and early XD engines and been very happy with performance gain and fuel economy.
If Gem Qld are like Gem NSW, it's 20 or 40 over, all the ancillaries simply kitted, no zero decking or cc'ing or checking the CR - or, for that matter, cam dialling. Probably a reground cam, the bare-bones timing set and new lifters. I don't know why it is, but my experience has been that when a Repco recon is dead, it's truly FUBAR (wear everywhere!). Note that Noel called for compression testing...

Just about any new cam for a crossflow needs dialling and needs heavy duty springs (compared to factory). Crow for one, are explicit in this aspect of their instructions.

FWIW, "wholesale" on a Crow 14776 or 14602 is about $240 plus GST. Waggot exchange units are well under the $200 mark.

You will be voiding your residual warranty (if it's the 3/100) by doing this work to the motor.

My intention was to conert the car over to ULP before i start fitting cams and the like due to the differences in the heads. I'm not worried about the warranty as the motor was installed by the previous owner.

i have thought about leaving the iron head on there but i would rather have the alloy head as it is a much better setup.

btw, i think i know what u mean about the dowels now but how many water passageways go the the combustion face of the head is it just one a front and one at the back?
PM the Jack Meister. Jack Lives here...he fitted up an Alloy head to his little US 200, and has had the pleasure of two Aussie 250 engines. There are pictures on his X-Flow Chronicles article under the Tech Section.
thanks for all the help guys i think i've got it all sorted and am picking up a complete XF carby motor for parts in about a week. I only have one laste question which head gasket do i use with a XF head on the XC block?