I know it's been stated as possible. But just what's involved in plonking a 4.2 into my engine bay? I have a 4.2 from a Series III XJ6, which I was planning on fitting to my S3. But I'm thinking now of fitting it first to my S-Type, so I can use it while it's 3.8 gets rebuilt, which may take some time. So how much of a hassle is it to fit? Can I use the EFI, or will I need to use the SU's of the 3.8? Will they just bolt up to the 4.2 or will I need to make an adaptor plate? Will I need to swap Sumps, & is that even possible? & any other real world problems that people have encountered doing what I want to do will be appreciated to.

 

Why not just wait until the 3.8 is finished ???
How much time are we talking about here for the 3.8 ?

 

I'm keen to live vicariously. I have access to a 4.2 with carbs from a Series 1 and my S-Type also needs a working engine for cheap.

 

It's more a case of how much money we're talking about for the 3.8, which is around $10K, to the standard I want it done to. This may take me some time. So the 4.2 gets me on the road in the mean time (& it will be a mean time, carving an extra $10K out of my budget) In fact I'm more likely to pull the 4.2 out of my S3 & see how cheaply that can be put back together, & still be done right. I suspect it will be a long way south of $10K. & that will get both cars on the road within a budget that won't see my living on 2 min noodles!

 

carrying over the Fuel Injected Series 3 4.2 engine into the S type won't be easy and chances are you will not get it right, it needs to be a carburetted engine for the S type.

a 4.2 from a 420 would be an easier job. Save the time, money, and headaches, don't butcher the S type, find another 3.8 or even a 3.4 for the S type. Horsepower difference between the 3 engines is nothing to rave about. The real difference is the 4.2 is a smoother engine.

sounds like you have the money to do it, go to google and get an already rebuilt engine with a warranty.

 

The first point to make is that the 4.2 is the same size, physically, to the 3.8, or the 3.4 for that matter. However, I suspect the inlet manifold for the EFI-fitted Series 3 engine will not fit between the engine and the off-side wheel arch, so you would need to fit a set of carbs with their inlet manifold and air cleaner. Then you have the problem of what needles and jets to use for the greater air consumption of the 4.2 over the 3.8.

 

I'm actually thinking of doing it for financial reasons, & I do want the original 3.8 back in it's home, but not until I've spent a mozza on it. I'm an SFR (self funded retiree). So most of my money is tied up in property trusts, stocks & bonds etc, & I get regular pay outs throughout the year, which is how I fund my hobbies/passions. I've also got a small trading fund, which I use for riskier trades, & it sometimes gives me a payout that allows me a few mad moments, but I haven't had one of those for a while. My other extra income earner used to come from gold prospecting with a metal detector. But I find that a bit too difficult now, with my stuffed arms, & I only go out prospecting when I can talk my Son into coming out with me. Anyway the up shot of this is I need to get creative about what I can achieve on a budget, & I was just wondering whether I could slot the motor I already have into my S-Type, before it takes up residency in my S3. I want to do this because I want to drive around in my beautiful S-Type asap, & while I still like my S3, it's the one I'd prefer to see sitting in my shed awaiting funds. It won't be too long. Even without stock market windfalls, I should be able to fund both cars thorough resurrections (both cars fitted with rebuilt original motors & spare 4.2 done up to race specs, for track work) within the next 2-3 years. Which isn't too bad, considering what I'm planning.
My Mechanic indicated to me that it wasn't too difficult to convert an S3 Mill to Carbies, which is what set me thinking. & I wouldn't do anything, to either the cars or the motors, that couldn't be easily reversed. So there's no worries about butchering anything. Neither my Mechanic or I would let that happen. He's a bit of a stickler for originality. So I could probably only talk him into this, as long as it's completely reversible & of a strictly limited timescale. I have invited him into this thread. But he's very busy in the real world & hasn't much time for internet chats. So he might just lurk (so be careful what you say about him ) Though I really hope he throws in his 2c, as he's very knowledgable & would have much to contribute.

 

If you intend to swap back to the 3.8 then forget EFI, the S3 head is different to the carbed S2, so I don't know if the carbs will fit, you may need the manifold from a S2 and re-jet the carbs, you could talk to SU about that they can probably tell you, but your carbs are probably HD6 1.75" and the 4.2 ran with 2" HD8's, they may be ok with correct jetting, but you need to check with SU.

You should be fine with the sump, there should be no issues, using the bare lump should be fairly straight forward, but you need to check carburetors and exhaust fit on the head.

Jose is right in saying not to butcher the S type, I see your problem re budget, so finding another engine may not work as you have a "free" 4.2 S3 you can use, you may get away with your existing carbs, but you will lose some power with smaller carbs, but if it's just to tide you over til you get the 3.8 rebuilt then you may not be concerned about that.

I was a little slow typing so there have been further posts, so ignore the "butchery comment" as Fraser says the lumps are the same size, getting the fuel in the motor will be you only real issue.

 

Oh well. It was just a thought.
Thanks for the input everyone. Looks like the S3's going to be getting the new Mill, & the S-Type can just wait until it's 3.8's ready to roar again. It just kills me every time I roll up the shed door & see it's sleek svelte curves just sitting there, waiting to be taken for a cruise. I've never been that good at patience.

 

Bank robbers loved the MK2, maybe that's a short term solution !!!!

And on the upside if you got caught you couldn't look in the shed for a few years so you wouldn't have to suffer ... Ah then there's the patience problem, back to the drawing board I think my plan seems to have some issues !!!