Hi, I recently acquired (for free) a rebuilt 4.2L XK6 engine. The block number is 25954 leading me to think it came from a Series II XJ6 from about 1978. The engine came from the family of a Phoenix area Jag owner/enthusiast who owned several XJ6's and an XK-120. Although its been 15 years since the rebuild it looks pretty good. I pulled the cam covers and the cams look to be new. Light oil covers them. I pulled the Bosch-Lucas FI system completely off, also the exhaust manifolds. The ports in the head on the exhaust side are ugly: coated with a thick, white powdery substance. The exhaust side is clean. There are new, bright shiny half dollar size copper "washers" on both sides of the block. I'm assuming the bottom end was rebuilt too, but will have to dig deeper to be sure. Once I figure out how to loosed the cam gears I'll pull the head and check out the pistons as best I can, also the valves. So, I would like to use this engine in a C-Type replica but like most people don't want to break the bank. I'd like a strong, not race, engine. From what I read higher compression pistons, some head work (port, polish, flow) and carburetors are the trick. I'm hoping this can be done for $5-6000. If this is pipe dream shout out and tell me so! If not, any advice and help would be much appreciated.

Bob

 

Bob;

That stuff in the manifold is alloy corrsion. Water got there some how!!! f not pervasive,vcan be cleaned and no harm.

Before you go too far, seeif it will turn over. By power or by hand. Caveat, CW only, not CCW!!!

New tight alloy pistons can seize in the iron bore!!! At times OK. At others, a tear down is the only hope.

those copper thigs are "Welsch" plugs. In te lock to remove the casting sand. Also incorrectly referred to as "freeze" plugs. A good sign that some work was done.

Either EFI or carbs an interesting enmgione for a project !!!

Carl

 

sounds like dry antifreeze/coolant residue at the 2 intake water holes.
$5 to $6 grand sounds like a rebuild,
Why spend so much?

Cheaper to build a stand with radiator, battery, switch, and run it. If it seizes, then you spend the money to rebuild it.

it takes a lot and lot of abuse to damage the 4.2 engine, and even then, they refuse to die, worst that can happen is you need a head gasket job.

in the US, there is Team CJ who does the kind of work you mention. I do not know about their reputation so do your homework and research them. They are here:
www.classicjaguar.com

 

Yes, it turns over with a wrench on the pulley nut, but tight. I shot some WD40 down each spark plug hole and it loosened considerably. Thanks for the reply and I'll let you all know how this project goes.

 

God ideas and thanks. Assuming the engine was rebuilt properly and runs good, what about performance upgrades? The Fuel Injection system looks rough and I may need to buy a manifold and carb(s) just to get it running. Is there any way without pulling the pistons totally out to confirm they are stock? Numbers stamped on top maybe? The head defiantly needs to be cleaned out, so it's coming off anyhow.

 

Things to check are:

Stakedown kit should be fitted on a good rebuild
Tappet Clearances
Take the bottom sump off and remove a couple of bearing/ big end caps. Condition will show if it's been rebuilt at a lower cost than the head gasket route. Also check the gunge built up.
Poke the welsch plugs to check if they've rusted out. Remove a couple so you can see the state of the head bolts at the bottom.
Check the oil pump clearances.

 

You can measure them or easier, measure the bore, preferably length ways down the block. Should tell you if the pistons are oversize if you get the data.

 

Good stuff, thanks! I ordered an engine maintenance manual today. Any suggestions on performance books?

Bob

 

There is probably more info out here on the internet than in any book these days. If you are serious about putting the engine in a Ctype replica, you will not need a great performance upgrade. C types weigh less than 2300lbs all up. Just make sure the engine can rev out properly, use either twin HS8 or much better the triple SU setup with straight port manifold. 9:1 pistons are good, don't bother porting, use an electronic ignition. There are some really nice extractor systems around now, unlike many years ago .when I had my E type.

 

That's all good news to me because it sounds like a strong reliable engine that won't break the bank. What horsepower would you expect to get from this setup? I just don't want Miata's blowing me off the road!

 

When you have the head off, check for cracks between the bores.

 

I will for sure. Also hoping to see domes on the pistons. Wouldn't that indicate that hi compassion pistons were installed during the rebuild? Since the cams look to be either new or rebuilt/ground, I'm also assuming the valves were done at the same time. Wondering it maybe I'll send the head out to a shop for a good look over...

Bob

 

Do a compression test before you take head off.
That should show up any weaknesses in the valves or rings.
BTW is the stakedown kit fitted?

 

What I meant was "between the bores in the block"

 

I don't know about the "takedown kit" being installed. I'm new to Jag engines and am anxiously awaiting my engine manual. Is it something obvious externally?

Thanks,

Bob

 

Despite what others say, forget about the "stakedown kit" Its a $100 set of plates to hold the tappet guides down. Needed on late engines that ran lean and hot due all the crap in the engine bay. Not invented when I had my E type, and used to drive that hard. Never any trouble with the tappet guides.

 

I agree you don't need as takedown kit if your tappet guides are installed with a proper tight interference fit.

I had my top end rebuilt after the damage you can see in this pic (if I attach it properly), caused by the guides drifting up and being hit by the camshaft lobes. Now rebuilt so no need for a stake down kit. I hope.

 

And here is a stock pic of a shakedown kit:

 

Sparkplug, I like your red "champion" lead connectors. Mine were red originally, but I bought a new set from a UK supplier and unfortunately they are black.

 

Just looked at my posts:
it is a "stakedown" kit but the ****** auto correct keeps tripping me up to produce nonsense.