Calling all MK X /420G Experts

[Thorswhisper]

Lets build a nice, practical, go anywhere driver. Base car will be a 1963 MK X.
Electrics and all its limitations will be retained, ( Unless it makes A/C system impractical). Body and electrics are very good.
Which engine to retain? 3.8 or go with a 4.2 and related carburation?
Front Suspension- leaning to 420G with better steering box and brakes.
Rear suspension- leaning toward upgraded 420G with 3:31 ratio and better brakes. I understand there was a wheel design change for the larger brakes of the 420G? Unsure of what to do with Brake master.(XJ6?)
Fuel delivery- Upgrade submersible pumps to external?
A/C options- Have access to a trunk mounted Delair unit but are there better alternatives and which compressor/ condensor system to go with?
Cooling system improvements?
Any and all thoughts greatly appreciated.

[awg (tony)]

@Thorswhisper

Lets build a nice, practical, go anywhere driver. Base car will be a 1963 MK X.
Electrics and all its limitations will be retained, ( Unless it makes A/C system impractical). Body and electrics are very good. [/quote]

The 3.8 Generator does not put out enough Amperage to run the A/C compressor and fans, especially at night or idle. I have a 70A Lucas “Universal” alternator fitted

@Thorswhisper

Which engine to retain? 3.8 or go with a 4.2 and related carburation?

I would not change unless I had to

@Thorswhisper

Front Suspension- leaning to 420G with better steering box and brakes.

big considerations here…are you LHD or RHD?..LHD parts in particular are rare

There is the following complication…around 1967, the engine mounts moved from on the body to on the IFS. I am not sure how to get around that.

What would be an upgrade for you is an early (65-66) 4.2 MKX front end, with Adwest steering box, engine mounts on body, bigger brake pads.

I have a '66 that has been converted to XJ6 Brake booster, master, calipers,and steering arms
This compromises the steering badly, and should never be attempted

late MKX- 420G has the biggest brake pads, you can fit them with their 1/2" discs, quite rare and expensive.

420G has the same booster master cyl as S1, early S2 XJ6
The ultimate upgrade would be to transplant complete 420G engine,auto trans and IFS
(You do not say if you have rare manual trans ?)

An entire XJ6 front end was grafted on by one guy, needs advanced skills, and engineering approval here at least

@Thorswhisper

Rear suspension- leaning toward upgraded 420G with 3:31 ratio and better brakes. I understand there was a wheel design change for the larger brakes of the 420G? Unsure of what to do with Brake master.(XJ6?)

maybe different in Europe but every vehicle I am aware of is 3.54 auto/manual or 3.77 MOD
I do not think wheels changed
I would not be overly concerned with the rear, they are largely unchanged thru production

@Thorswhisper

Fuel delivery- Upgrade submersible pumps to external?
A/C options- Have access to a trunk mounted Delair unit but are there better alternatives and which compressor/ condensor system to go with?
Cooling system improvements?
Any and all thoughts greatly appreciated.

• with the fuel pumps, if they work, leave them, if busted, replace with out of tank units imo

• The factory A/C is apparently good, as the evaporator is big as a Mack Truck, my car was originally non A/C, and I am fitting parts, long story

• No enhancements to the cooling system should be needed, unless your radiator is not partially blocked

one “bad” thing…3.8 have a solid steel fan without a Viscous clutch, so chews a lot of power at high RPM

[Norman_LUTZ]

@Thorswhisper

Which engine to retain? 3.8 or go with a 4.2 and related carburation?
Front Suspension- leaning to 420G with better steering box and brakes.
Rear suspension- leaning toward upgraded 420G with 3:31 ratio and better brakes. I understand there was a wheel design change for the larger brakes of the 420G?

I’d definitely use the 4.2 engine,more torque, better engine response. Also go with XJ6 15" wheels, more tire choice as well as after market wheel choices (Chev same bolt pattern).

[Micah_Wellman]

Mark X BW transmission is problematic. I would go with a later 420G unit or a T5.

If you go with a T5, keep the rear end and the 3.55 gears. Watch out for drive shaft diameter half shafts. You may experience them hitting the shocks with modern wide radial tires.

Burman power steering box may not like the modern tires too.

Micah