4.2 Big Valve Head Swap

[politeperson]

I have hatched another pointless plan for my E type which is now under way. It is already going wrong.

My car is running very well on a standard engine with my Emerald ECU and Jenvey throttle bodies. So I thought I had better try and mess it up.



To that end, I have got off to an excellent start by purchasing a broken cylinder head from a fuel injected S3 XJ6.

I dropped it of at Johns secret shed (the XK/Aston guru). Yesterday for an inspection.

It looked ok yesterday when I picked it up and handed over the dosh to the seller.

However all my dreams of a cheap quick rebuild were quickly destroyed by 9.30am when John rang me up and told me it needed welding. What do you expect when you buy 32 year old cylinder head I suppose.

He thinks 2 of the valve seat holes look dodgy.











Maybe 2 out of three valve seats have porous material behind them that have allowed water though causing a bit of alloy erosion.

So rather than give up, the otherwise OK head is off to Spalding to be welded and machined, by more top secret engineers who do this sort of thing in their sleep.

Welding and new valve seats, maybe some porting? Then back to John.

The plan is to pull the manifolds off my car, remove the complete head and do a swap in a weekend. I dont like idea of it lying around in bits.

Then I intend to drive over to Emerald for a remap so I can see the power increase (or not) with the same set up.

Theses later head have larger inlet valves and the fuel injection cams give higher lift.

Then the esteemed forum members will know whether all this shenanigans is actually worth it!

Apparently.

[christopher storey]

Hmmm. The head looks slightly odd to me , in that to my untutored eye the valve guide bosses look to have been very considerably shortened. Also, was the porosity revealed by pressure testing, or is it just a result of inspection with that rather odd pitting? I am wondering in other words whether there has been some extensive interference with the head already , with the pitting occurring perhaps when new seats were fitted ?

[politeperson]

Maybe,

The porosity is just a guess, the head has not been pressure tested yet. Will be shortly. Apparently it is going in some kind of chemical bath tub first.

Maybe it has already been gas flowed by the Jaguar works team?

Or maybe it has just been attacked by some idiot with an angle grinder in a shed?

All will be revealed shortly I suspect.

[phil.dobson@mac.com]

its a lot of work, time and money for a very limited upgrade in performance. No doubt the rolling road test will show better figures but I doubt you will feel it.
One last comment though...... Please fit the in tank High pressure pump (and return line) I sold you with the fuel injection kit!

[politeperson]

I promise I will Phil

[politeperson]

So,

I showed the eroded cylinder head photos to a couple of firms that recondition cylinder heads and do lots of XKs. The consensus seems to be that they recondition worse ones all that time and this one should be OK.

So, armed with the exciting prospect of not having to spend money having new valve seats, I took the head back to Johns, who crack tested it and it passed. He was working on all sorts of old stuff including an MG P Type engine, a 1910 tractor engine and 2 Aston Martin engines. He had about 5 other XK engines as well.

It all goes back together with a warranty I assure you. The bottle is for steadying the nerves.







John tells me that the cams in my head have a lift of .39 inches. They are unworn.




He also says the inlet valves measure about 47mm diameter. So it looks like it is a big valve head. "Thats nice then".

The valves buckets and cams have no measurable wear.

So it looks like guides, springs, stem seals, sprockets, cam bearings and maybe new buckets. Maybe not new buckets we will see.



The plan being to get it sorted and swap it over with my 67 head.

[christopher storey]

New buckets cost, in relative terms, buttons and it is a false economy not to replace them. The problem with buckets is that they go barrel shaped, rock in the bore as a result, and cause noise however accurately you shim the tappets

[chrisfell]

One assumes that all of these modifications are aimed at obtaining more horses when hurrying along. If so, then on the list of things to be done could (should?) be is port matching.

[mark10337]

Is the head from the 8LxxxxxS engine series or 7Lxxxx ?

[politeperson]

Yes Chris, we shall be looking at the ports shortly.

The head was not on an engine, so I dont know the engine number, later heads dont seen to be stamped anyway. I would assume 8L.

This head came from a chap building a Realm C-Type near Milton Keynes. So that was three people building a C-Type I spoke to in the same week!

With regards to big valve XJ6 engine numbering, I have discovered the fuel injected engines all have an 8L engine number. They also have a number greater than 50,476. The will all be from the 1980's (an 8L prefix).

If the engine number is greater than 8L50476 and it is fuel injected, it will probably be a big valve head.

This means
It will be a newer one (corrosion wise),
Larger inlet valves,
larger inlet and exhaust ports I noticed,
Thicker cylinder head castings,
Higher lift/duration PI camshafts (bit like the "D Type" spec).
Probably some other differences.

I am not aware any twin carb. engines on the S3 XJ6 or the Daimler hearse that came with big valve heads.

Of course Jaguar are a bit of a rule to themselves so I stand to be corrected.

Yes I will change the buckets. What was I thinking. John will also plug the rear two water ways that will become redundant in the head.

[Woolfi]

The 6 short aluminium trumpets look very "sporty". I think they are too short. The length from the "mouth" of the trumpet to the valve seat determins the rpm, where the filling is best. The shorter this way is, the higher is the rpm. The jagar 4,2l motor has a long stroke und therefore the revs of max power can't be high. For a rpm of roundabout 5000 - 5500 the lenght of the complete intake system shall be roundabout 40 - 50 cm.
1. I would try to find some trumpets which are 8 - 10 cm longer and test the short trumpets ans the longer on a dyno. After this dyno session, you know better, which length if better.
2. You check / measure the length of a intake system of a XK oldtimer-racer. I think , that the revs of max power is 1000 - 1500 higher, than of a normal motor. Then you can calculate, how much longer the trumpets shall be on your motor.
3. Check the length of the intake system of a mercedes SL 300 gullwing. Allthough the rev range of this motor is higher than the XK-motor, the length of the intake system is bigger than on your XK-motor. Therefore I think, yours are to short.
Regards Wolfgang Gatza

[politeperson]

Thanks Woolfi, interesting thoughts.

I never go near 5,500 rpm and have no intentions of either!

I think exploring those regions of the rev counter require serious expenditure in the Rob Beere department with regards to crankshaft (4,000), pistons and conrods £3,000, etc.

http://www.rob-beere-racing.co.uk/engine.html

My pockets dont feel that deep at the moment. I will leave it to the e type racers whose corporate sponsors pay the huge bills.

Unless I win the lottery.

On the other hand, for the S2 block lying in the shed, I might well go down the route of 4.5l pistons and liners.

[politeperson]

Well my new head is done, picking it up tomorrow, so this afternoon I thought I would start to take my existing head off. I need to get it done as I booked into Emerald in a couple of weeks for the rolling road.

You have to break an egg to make a cake, or something like that.

I drained the coolant, I shall reuse it. Its new. Set the engine to TDC. Used the Jaguar cam tool and my dial gauge.



With my manifold, the lower row of nuts are easy.



I pulled away both manifolds and the alternator way, placed then on cardboard so I dont scratch my frames.

I detached the sprockets. Going to fit 4 bolt ones on this head.

I decided to take the cams out for safety. My old head is still like new really, with 3,000 miles on the clock. Anyone need a straight port head for a Series 1/1.5/2?

Maybe I shall keep it for my next project. It owes me quite a bundle. Have not decided yet. I need to get stuck into my Series 2 long stud engine soon.



And before long, the head was off.

What have I done?

It will be OK. I have the advantage of a misspent youth in the motor trade.




Next chapter tomorrow!

And I will be at Stoneleigh on Sunday. Looking for S3 bits with my friend.

Who is going?

[mgcjag]

Great stuff James....will be at Stonleigh...will look out for you... Steve

[politeperson]

Steve, yes I shall look out for you, look forward to it. Bargains!

I got more done this afternoon, after I picked up the head from John.

He had just received 2 more XK engines from London.

I cleaned up the deck with scotch bright and checked tdc with a dial gauge. Zip tied the cam sprockets in place.




I tapped the head down level.


When I got close to the cam sprockets the clearance looked tight so I removed the cams and refitted then when the head was down. I carefully kept the cams in the correct position using the cam locking tool as they tightened down. I torqued it all down.







I was then able to fiddle the center out of the sprockets and align them the the cam to complete the cam timing. I reset the tensioner, rotated everything a few times on the crank, rechecked the cam timing and all looked good.

I was the able to refit the alternator, exhaust manifold, coil pack and inlet manifold. A good afternoons work. Maybe try and start it tomorrow? or Saturday.

[politeperson]

So I buttoned the rest of it up, checked my torque settings and cam timing again, hooked up the battery and vroom. Sounds good.

But, I have an issue preventing me from finishing the job and driving off into the sunset (rain).

Can any one spot the deliberate mistake? Lucky I am going to Stoneleigh on Sunday! I will be able to get what I need. I hope.

Clues---

1) I have now have a Series 3 fuel injected XJ6 head on an early 4.2 block with short studs. Picture below.
2) I do not own a Jaguar breakers yard

James

[politeperson]

Well, how crazy is that.

The answer to my puzzle is that I need XJ6 S3 cam covers (maybe S2). My nice old rounded polished covers wont allow me to plug the "oil gap" at the back of the head.

The later heads lack the tapped holes at the rear of the cam shaft for the cam seal plates with 'O' rings, as found on earlier cars.

Later cars have flat faced cam covers at the rear, so you only need to plug the half moon gap at the back of the head.

This is the strange bit though.

After I posted my puzzle (2 hours ago), I went on ebay and found someone selling a pair of S3 XJ6 cam covers 15 miles away for £30 the pair.

After I pressed the buy in now button, he delivered them an hour later, as he was coming this way to pick up his daughter.

I now have the missing pieces of Jaguar. What a coincidence!

So first thing tomorrow I can give them a cosmetic overhaul and fit them.

[politeperson]

I polished the cam covers, fitted them, struck it up and checked for leaks. I now have more correct looking ribbed covers.






All vital signs normal. I checked the throttle body balance and the fans. All OK. To miserable for a test though. Snow, Ice salt everything around these parts.








That just leaves my poor forlorn head. I have reassembled it, leaving the cams loose and oiled.

Dont worry it will be living in glory soon, hopefully on another E type.

[politeperson]

Well I managed to take her out for a spin today and measure the compression.

She certainly seems to have some go.

The cylinders hot with the butterflys open are reading

1-173psi
2-171psi
3-175psi
4-174psi
5-173psi
6-171psi.

So thats good then, all about the same pressure across the cylinders.

As far as acceleration goes, bottom to middle range is a bit better, mid to top end seems a lot better. I would say it the engine is breathing more easily.

The other head had smaller ports, smaller valves and lower lift cam. Its all a bit subjective, but I am quite happy. I am booked into the rolling road next week. The other head wasn't exactly slow though, dont forget.

Here is a picture of the pressure gauge and you can see the colour of the spark plugs after 50 miles. No oil leaks yet. Le Mans Classic here we come.





I didn't have the speedo on screen on the first film. Just as well officer. It is still a bit sticky on the second film.

[politeperson]

Well, getting to Emerald on Thursday will be pretty tight, considering the whole rear of my car is in bits at the moment.

I found and oil leak all over the rear discs and a petrol leak from a pin hole in the tank on Friday evening.

I have tomorrow to re-assemble the IRS and re-fit it and also refit the newly re-brazed fuel tank.

I have all the bits to fit everything, even to replace the knackered 18 month old radius arm bushes.

So lets see how it goes. I am booked in at 9am at the rolling road Thursday morning.

I have painted the fuel tank and reattached the re-sealed output shafts and bolted it in the in the cage.

The order of reassembly is now-
Calipers, shim and discs on diff, lock tight and wire. New pads.
Lower swing arm fulcrum with new seals
Shims, drive shaft on discs
Shocks with upper mounts bolted to IRS
Lower dog-bone mounts on diff with wires.
Lower cage plate bolted on.
Fill diff with LSD oil.
Attach handbrake mechanism new pads.
Raise cage into car, rear mounts in situ.
Jack up each side to attach front radius arm mounts
Lower each side to attach lower shock mounts.
Attach Prop+Handbrake.
Bleed brakes.
Wheels on.
Done.

Glue sound insulation in boot
Glue tank pads
Attach vent pipes
Slide in tank.
Connect filler
Bolt in tank, sender and pickup reattach wires and fuel line.
Reattach Trim.
Done.

Hopefully.