I read about the cooling problems with 4.2 liter straight six jaguar engines...read about cracks, failed sleeves and grooves being cut to mix hot and cold coolant...i wonder should i do a 350 gm v8 with a turbo 350 trans?
should i look for a 2JZ-GE toyota straight six? or an old 250 GM straight six?
very little funds available, just looking for a power train that will have parts available in the distant future..
Any advice out there?

i have a line on a 72 xj6 motor and trans with carbs i think, for $500 bucks on a pallet or the entire car for $800 BUCKS.

i have 900 available until next month when my disability check comes in...
or should i wait AND go a different route?
a guy in troutdale oregon wants to unload a running engine and trans on me a tripower...3 carbs, 4.2 liter for $500 bucks...any comments out there?

 

Why not get a proper jaguar engine (eg 3.8 or 4.2). I guess I am not the best person to comment because I have to admit that in my opinion if you are asking the question you are about engines, would you be better off selling the 3.8 and getting an old chevy or ford?

 

I would find a 3.8 XK engine with B Type twin carb head with Jaguar manual all synchro gearbox (not Moss box) and overdrive. You appear familiar with some of the 4.2 maladies.

 

Jaguar fitted a Daimler V8 to the Mark 2, and the car was sold as a Daimler in the UK. This was a small V8 of 2.5 litres, but there was a large over 4 litre engine which was never fitted to any Jaguar. These engines came to Jaguar when they purchased the bankrupt Daimler company.

If you're strapped for cash, then the only real option is the $500 1972 engine & gearbox from an XJ6, as the dimensions are identical to the 3.4/3.8 litre engines used in your 3.8 S-type. Anything else is going to cost money just to install it. The engine with 3 carbs won't fit due to lack of room at the front of the engine compartment, but this is only because it has triple carbs, it will be identical in all other respects to the engine out of the XJ6.

 

A big problem with the early cars is the proper style thermostat wasn't available for many years. If it doesn't block off the bypass port up to 50% of the coolant will circulate within the block and never go through the radiator.

I adapted a thermostat from an early Series type Land Rover ( with the 2.25 petrol engine) and it has resulted in noticeably lower running temperatures.

For the 4.2 engines from about 1968 onward, the thermostat that Jaguar specifies isn't correct - the foot does not extend far enough to block off the bypass. This applies to the V12 engines as well. Use a Gates 33188S and drill a small bleed hole at the top.

 

The correct thermostats to block the bypass ports with their shrouds is crucial as you say & head dependent. All bypass ports are not the same. We cover it elsewhere here.

 

The Jaguar thermostat is logical, too logical for others unfortunately.

Which engine? I prefer to keep it Jaguar. To maintain the vehicle's historic status with the UK's DVLA, I believe it would have to be an XK 6. If that's not important, then the AJ6/16 maintains a lot of character, saves some weight, lasts forever and is nicely powerful.

My vote is an old 3.4, rebuilt, tuned and polished.

 

The 3.4 is also a fine call. Great smooth engine & only 10 bhp in it to the 3.8 in twin carb form ~ although that does not tell the whole story when torque is considered.

From the OP's comments it would seem he has read the following re the 4.2.

https://www.jagtas.org.au/torque/tec...-engine-block/

 

I can confirm the truth in that article, as I had a cracked block back in the late 80s with a 1980 XJ6 I had bought. (the quality of this 8 year-old car was also appalling as I found out later). I believe the article was written by a chap I met to buy a bootlid from and during the conversation asked had I had HGF problems. He got me out of my HGF problem by selling me an uncracked 7L block with pistons for £100. His business was rebuilding XK engines and he told me that, on average, 7 out of 10 7L blocks were cracked when he stripped the engine down, and 8 out of 10 8L blocks. Only when the slotted block was introduced was some increase in head gasket life delivered, but as explained in the article, not even this gave a long life with failure in the 80-90k miles range. Of course the head studs going through the coolant was not ideal, but OK if the owner is meticulous about replacing the anti-freeze. This is not because it ceases to provide frost protection, but because the corrosion inhibitors included in it, lose effectiveness. Modern OAT antifreezes last much longer, of course. Note that the V12 engine also has the head studs in the coolant as well.

The good news is that a 1972 engine may not be affected, even if it's a 7L block because the trouble was linked to various bad practices in the Jaguar machine shop in the 70s. Iron castings would normally be "weathered" for many weeks to allow stresses in the casting to work themselves out, but under "new management", this was speeded up to cut costs, and blocks machined within days of casting with the results we see today. The lipped liner modification is best, but expensive. From what jhemp has told us he just hasn't got the money to pay for expensive jobs, in fact I would think trying to run a Jaguar on a shoe string is heroic, but not really achievable with a car that old.

 

If I wanted to achieve the most powerful XK and had sufficient budget, I'd start with a 4.2. In view of the age and availability of 3.4 and 3.8 engines in the US, a well preserved 4.2 of one of the better years (early, late and some in between) may be the most economical XK solution. In the UK, AJ6/16 are fairly cheap, but there's some effort to fit them.

Gearboxes, now that's a widely discussed subject. From what I've read, my preference for manual is stick with OE or swap to a Toyota or possibly Nissan. If I'm spending a lot of cash to swap, i want a quiet box with a smooth change. For automatics, there are GM and ZF 4HP swaps if you want an overdrive. The best of all worlds might be a ZF 6HP or Ford 6R80, if only suitable adapter kits were available. For the present, my own plan is to do some work on my old Moss box (with OD) to improve the change mechanism. But I may be over sympathetic to the Moss as I learnt to drive with it.

 

Yes. It's all about the money one has to, or wishes to, spend & location.

I like the XK 3.8 because it is relatively free revving, adequate torque & its cylinder liners made from Brivadium, an alloy developed by Bristol for its sleeve valve aircraft engines. It is one of their best features. It's only possible negative is the maximum rebore permitted + 30 thou after which new liners should be fitted. The good is you can take it back to standard easily.

I like the 3.4 for it's smooth easy revving nature & while it's cylinder bores are less durable it can be rebored to 60 thou.

I've always been a bit scared of 4.2's

 

I agree with Fraser as it sounds like your funds are limited. I am more open minded to engine swaps that some purists but when I read you are on disability I would caution that restoring a Jag regardless if you want to be stock or ok with a modified car is likely going to be a challenge if you do not have money as these are not cheap cars. The Toyota JZ is a great engine and blows the doors off any Jaguar but that along with a GM LS would be the good choices for a non Jaguar swap but those are NOT for anyone with limited funds. Retro Power is doing an incredible "Project Utah" MKII that is better than the Callum MKII using the Toyota engine but that is a $100K + build. I've done the GM LS and yes like the Toyota you will get way more horsepower, reliability but both are going to be expensive to do all the necessary mods to make it work. A straight 6 Chevy would degrade the value and not a powerful engine. To me the stock Jag as Fraser said that you have is the best as the engine swaps that will be desirable and command good resale are not within your budget likely and rebuilding the stock is also going to be big dollars if done right.

 

1972 4.2 block, crank is .030 rods and mains, bore is 3.655
bearings look hardly used, piston skirt wear is minimal, repco ACL 319 pistons with 8.1 comp and a single oil ring
only one oil pump bolt was the correct dowel pin type, i believe there should be 2 for alignment...but after i pull the studs, and hottank the block i will have to decide if i want to deck the block and remove the .003 inch liner protrusions.

heck, what do you want for 100 bucks, and i got a BW 12 auto tranny and torque converter included...anyone out there need a transmission?
im in oregon USA.

then theres the 1987 4.2. fuel injected motor with cyl head complete, minus the thermostat housing, i might block off the injectors and put a 600 cfm edelbrock adapter where the butterfly goes...that motor cost me 500 bucks, have yet to tear it apart.

also picked up a good borg warner 66 all aluminum 3 speed for 200 bucks

wondering if the 87 head will fit the 72 block?
and should i deck the 72 block to eliminate the liner protrusion of .003 inches?

 

I will be interested in the opinion of others on liner protrusion. I don't know Jaguar 4.2 practice with their block cracking issues. With Alfa & Aston there is a spec for liner protrusion. They are supposed to protrude or you will blow head gaskets. The linered 3.8 XK engine you skim the block to flat ~ zero protrusion.

Yes there are differences. Alfa runs fully wet liners whereas Aston runs top & bottom sealed dry liners with an air space around the liners.

 

If you have the EFI engine, I would use that as is. The EFI head had the largest valves. It will drop onto the 72 block, but if it's already on the 87 block there is no reason to take it off if the block is good.

Do you have a carb manifold for any of the engines? A set of SU or Stromberbg carbs will be a much better fit, as the EFI manifold will not fit in the engine bay of an S Type without cutting away part of the firewall that supports the panel for the battery. You'd have to weld in a panel to seal off the footwell. A downdraft carb (like all the American carbs) really won't fit in the tight engine bay of an S Type. I'm not aware of any manifold that would allow a downdraft carb.

I think that if you take the time to understand SU carbs you'll come to love them - they are infinitely adjustable with a screwdriver, no more changing jets and metering rods. Haynes makes a manual for the SU's. I like them because there are very few moving parts. Basically the throttle plate, float, and the piston with a metering needle and that's it. No need for accelerator pumps and all the complications of Holleys or Edelbrocks.The SU's also keep their tune well, generally once they are set generally you never need to touch them again for years.

 

I'm no expert on the mechanical and structural aspects of engines so I may have this wrong. Liner protrusion is required with wet liners to seal the water jacket from the combustion space. It's possible as the liners are removable without great effort (?). With dry liners, the sealing requirement is reduced and it's difficult to remove the liner to reface the head. So I don't expect Jaguar would specify a value for the XK6.

The EFI engine should go into a Mk2 with a few swaps. Most have been discussed elsewhere. The oil filter and feed to the cams have to be re-arranged. For fuelling, the easiest is to swap to twin SUs. Triple SUs or fuel injection are possible, but need more work and are difficult on a budget.

 

Some time ago I bought a 3.8 S-Type that had been stored more than 20 years. After several months I now have it running perfectly. What makes it unique is that it is a 231 Buick (GM, BOP) engine with a Turbo 350 trans. Lokar floor shifter made a substantial difference since the original shifter just doesn't work with a 350 no matter how much monkeying around they did. Clean engine bay, and will be cleaner once I get rid of the 13" vac booster for a 7".

 

It appears that the liners are actually sitting flush with the deck, but the protrusions were tinl copper orings embedded between liner and block that were protruding, and were loose the the gap, not solid circles of copper, but like puiston rings...almost as if someone took a piece of .006 copper wire and tried to make a sealing ring on the outside of each liner???
wierd?
so the block is cracked at the top of each bridge as this photo shows

 

might either make a wooden pattern and have an intake manifold cast out of aluminum to put two 32/36 progressive webers on a common plenum...or purchase billet aluminum sheet and tubing and a tig welder to assemble an intake manifold....modifying the fuel injection manifold is also an option by placing two manifold adapters on top equally spaced..and welding, blocking off unused ports injectors etc.
since this 4.2 engine is going into a 1964 3.8S body i need all the room i can get.
maybe a reverse scoop in the hood, since i dont want water getting into the carbs when driving in the rain.