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2.4L MK2 1960 what major components need changed since car now has 3.8L motor
We recently purchased a LHD 1960 MK2 that was originally had a 2.4l motor, vin 125457 but came with a 3.8l already installed, but has original 4sp with OD. We want to change those component that should now be fitted to accommodate the engine change. I have looked at several vendors parts books and info provided by this forum trying to see the differences. So far here is what I have found thus far besides of course the actual engine.
1. Rear axle ratio. Car as I purchased still had the original 4.55 ratio. I have successfully pulled out tree stumps for some neighbors, but seriously I was in 4th gear OD already at 30MPH. To fix that, I have just completed a complete 4HA axle swap with the correct 3.77 power-loc diff which is correct. Car now drives beautiful.
2. Looks like the front springs are different from the part numbers. I have no way of knowing if they were ever changed on my car.
3. Car still has the original moss box and OD. I seem to remember there was a a comment made that the springs in the OD unit may be different. I can't find that in some of the catalogs.
4. The 2.4l had a single exhaust pipe which was still on the car when I purchased. I have since changed to a dual SS system-Sounds great.
5. The exhaust opening for the tailpipe in the rear valence is only one pipe wide. So at some point I need to widen the opening to better accommodate the twin tail pipes.
6. The left dash has the lever for the solex carbs choke. That is still there and of course does nothing. I am thinking if the starting carb on the 3.8 ever goes I might be able to use as a throttle?? Anyone have any other suggestions for the lever?
7. No power steering. It s a handful to turn the wheel when parking in tight spaces.
I am sure there are many more and also I am sure my car is not the only one has has had a transplanted engine. So any other major changes would be appreciated. Also if there were minor changes such as maybe interior, upholstery differences it would be nice to know.
Not all 3.8 cars came with power steering, it was still an option I believe.
I assume carbs, inlet manifold etc. have all been changed to 3.8 ones?
Other things to look at are rev counter which I think revs higher on a 2.4 and the speedo which is only upto 120mph on a 2.4.
The badges are of course different on the 2.4, not just the grille badge but also on the boot, my 1967 2.4 MK2 only has a MK2 emblem in the bottom right corner and doesn't have the jaguar script or engine size in the middle of the boot like my 3.8 does.
Other than the bits above and what you have listed I think everything else is the same.
Of course the one thing you can't change is the chassis number which immediately shows what the car started as, not that it matters one bit :-)
The tacho will read correctly, but the speedometer will read fast. You need one with the correct turns per mile. It's shown on the face - most, but not all, 140 mph instruments will be correct. (Your present speedo is probably around 1300 TPM and you want more like 1100).
For the overdrive, 3.4 and 3.8 cars use higher pressures in their hydraulic systems and more (or stiffer?) springs; the details are in the service manual. The pressure can, if I remember correctly, be adjusted and most likely the same goes for the springs. However, there are cars that have had their engines swapped without changes to the overdrive and, from what the owners report, they work fine. One example is Matchless who has described converting his 2.4 car to a 3.4 on this forum, JagLovers, and migwelding.co.uk. For myself, I've recently bought a gearbox and o/d that came from a 240 for my 3.4 engined car. I'm not presently planning on modifying the overdrive. If there's a problem, I'll look at raising the hydraulic pressure a little.
I assume that whoever swapped the engine also swapped the clutch.
I'm sure that after a while you will find something to control from the choke lever, if only to make it into a switch for the cold start carb.
We've had several long discussions on the options for swapping to PAS. It's probably better to search them rather than repeat it all. I have an XJS rack and home made brackets and an ex-420 Varamatic box on my workshop floor. At present, the odds are on the Varamatic. Matchless followed a novel route of using a BMW rack that is very narrow which helps with the geometry problems of putting racks in Mk2s.
Apropos the stance of the car. If the front springs have been left unchanged, (which I doubt), the car will be noticeably too low at the front because the 2.4 block is about 2" lower in height to the 3.4/8, so this extra weight of cast iron of the larger engine will drop the car on 2.4 litre springs.
I usually get these estimates way off, but I'm going to guess that the 2 inches of cast iron plus will add close to 50 kg almost entirely over the front wheels: roughly equivalent to putting a glamorous, motor show model on the bonnet!
Did you have to do that Glyn I was just eating my breakfast when I scrolled down and that came into view. A Subaru with gold wheels! What were you thinking?
On the 3.8 change over. Was the original car a 240 with the slim bumpers? If you want to age the car and make it look like a proper 3.8 Mk2 then change the bumpers to the thick twin railed or Armco bumpers as we call them. Having said that there were twelve 380s built in 1967 to 1969 mainly for the American market with the slim bumpers but this was not classed as a standard production model. Possibly using up the old 3.8 engine and built specially to some ones specifications.
Upgrade of front springs started in the Mk1 era with the move to the 3.4 engine.
"There was quite a lot more to the development of a 3.4-litre model than dropping the larger engine into a 2.4-litre bodyshell. The bigger engine generated more heat, so a larger coolant radiator had to be fitted. That in turn required a larger grille if it was to get enough cooling air, and to allow for the larger grille the front wings had to be modified. The 3.4-litre engine was also heavier than the 2.4-litre type, so the front suspension needed stronger coil springs. Then a twin-pipe exhaust system proved necessary to allow the engine to give its best."
And then again on the "Mk2 in May 1960 also brought stiffer front springs".
The front springs will need to be changed.
Changing the rear diff from original 4.55 to 3.77 will need a speedo change or re-calibrate.
Tacho is the same.ie no change.
Been there; done that.
The stance of the car does have a rake towards the front. Here is a photo from the pervious owner just before the sale to me in March. Since then the front bumper has been straightened.
The second photo I found on the web of a 3.8l. Its stance looks very similar to mine, thus I will at least for now leave the springs alone. But if I can determine the current springs are otignial to the 2.4l, then I will in time change them. By the way is there a way to ID the springs. Other classic cars I have owned had different color paint stripes to ID.
So the next big upgrade is to do something about the steering. However I am getting used to it. The car came with brand new Vredestein sports and I inflate the front to 33-34. After that AC this spring.
The ride height looks good to me. Mk2s look best with the centre of the front wheel at the centre of curvature of the wheel arch. Of course that doesn't guarantee the stiffness of the springs. I'd judge how the car feels to drive before making a decision on a spring swap. For handling and good steering, it's important to have both sides of the car at the same height.
For tyre pressures, I used to run 36 psi front 33 rear with standard 185 width radial Avons. I would still stop, get out of the car, and take my jacket off before parallel parking.
Your car would have had coloured stripes brushed vertically on the springs or marked on a centre coil (They tell you to disregard the long stripe which was plant rough grading of springs). If after cleaning you can't see them then someone has sanded or sand blasted them off & repainted or powder coated the springs or they have disappeared with age.
e.g. on an S Type. (which included blue on SA built cars ~ we made the springs here).
How we marked the locally made springs ~ sorry I only have pics of rear.
Last edited by Glyn M Ruck; 12-21-2023 at 08:02 PM.
It's difficult to adjust the spring stiffness in proportion to the weight difference between the two engines by an increase in wire diameter in a well controlled way; the necessary increment on diameter is about 10 thou. It would be easier by changing the total length of the wire (i.e. number of coils). I'd suspect it was done by relying on manufacturing variability and simply grading the springs by unloaded length (and possibly measured stiffness). So, I'm going to contradict what I wrote a while back when I think Bill raised this subject and say that distinguishing between 3.8 and 2.4 springs by measuring the wire diameter is impossible and may well give misleading results.
The ride height looks good to me. Mk2s look best with the centre of the front wheel at the centre of curvature of the wheel arch. Of course that doesn't guarantee the stiffness of the springs. I'd judge how the car feels to drive before making a decision on a spring swap. For handling and good steering, it's important to have both sides of the car at the same height.
For tyre pressures, I used to run 36 psi front 33 rear with standard 185 width radial Avons. I would still stop, get out of the car, and take my jacket off before parallel parking.
I set to 36 and 33 and the steering with the new radials is a bit more manageable when parking.
Thanks for the tip,
Also there are no color paint markings on the front springs, were painted black probably years ago.
12-20-2023, 06:58 AM
2.4L MK2 1960 what major components need changed since car now has 3.8L motor
I was thinking of Peter's "glamorous, motor show model".
