Head Gasket Leak

[Orlando St.R]

Fitted the head back today and now run into a snag with the thicker gasket, the studs are too short to refit the engine lifting brackets.

Blimey, Nigel. How thick was the gasket?

As an update I've spent a day doing the tappets as a few of them were less than 5thou (smallest guage I have) and reset the back to 8 and 10 thou - racing clearances.

Does that make for a noisier top end?

[NigelW]

The gasket is 1.8mm and as the head has been skimmed twice since I've owned it . On the last rebuild I replaced all the studs so I think the problem might be them. I'm not sure but does anyone know if the lifting g bracket studs were longer than the others?

No problem with valve clatter withthose gaps, don't forget the XJ engine is set much larger at 12 and 14 thou for what is essentially the same head and cams. 8 and 10 just give it a bit more head room to cope with extra heat, I'm also using custom made silicone bronze guides and hardend seats.

[cass3958]

does anyone know if the lifting g bracket studs were longer than the others?

On my engine the studs for the lifting points are definitely longer as can be seen on this photo taken when I stripped my engine down in 2014. You can see the studs one set in from the right stand slightly higher where the lifting hooks would sit. (One of the last last studs has been removed in this photo so there is only one of the last pair showing.)

[NigelW]

Thanks Rob for the photo. I've delved into the parts book and found the two different sizes of studs, the engine lifting brackets are fitted to stud C23610 that is 175mm and the rest are C23609 173mm. It looks like all the studs on my engine are the smaller ones, I don't think the studs were screwed fully into the block to enable the brackets to be fitted. Another call to SNG today required.

[cass3958]

There you go another problem that we did not even know existed solved.lol.

[NigelW]

Cylinder head went back on today, I ended up replacing all the studs as I didn't trust the old ones with signs of pitting. While awaiting for them to be delivered I pulled the carbs apart to replace the float valves and found one of the floats to have fuel in it so was not shutting off the supply.

[Orlando St.R]

That's looking very smart. That was fortuitous to spot the holed float while everything was apart. I switched to a stay-up float when I had the same problem recently.

aue-898.jpg (37.33 KiB) Viewed 2980 times

[Glyn Ruck]

Good to see her back together Nigel.

I think I must learn from you folks. I've recently had fuel filled floats & replaced with new brass. I think I must get some of these for the future. Hate it when the pump keeps running & I know I'm spewing fuel on the garage floor. So far new carb kits behaving.

[NigelW]

Cheers, I would have fitted those floats but I had a brass spare to replace the duff one. The rest of the engine was fitted up today and going for startup tomorrow, hopefully it will be leak free - but you never know!

[Orlando St.R]

We'll keep everything crossed for you, Nigel. You need at least one Jag on the road! I'll look forward to hearing it purring like a kitten at the JDC National Day on 4 August. Let's hope it's a little cooler than last year.