Head gasket

[66an]

I am putting my engine togehter and I am in a doubt of my cylinder head gasket.
There are a mismatch in size and shape between the water jackets in the block and the head gasket. It is oval in the block and cylinder head and small round in the gasket. And the water holes in the gasket does not have the same diameter on both sides, despite the holes in the block are the same size.
Is it wrong gasket? The water flow will for sure be reduced.
Its an old asbestos gasket.

[Mikael B]

The gasket you have is for XJ6 and not for E-type.
I would source another correct gasket.

[christopher storey]

There should be no difference between an XJ6 gasket and one for an E type , except that the XJ6 will always have the extra 2 holes at the rear whereas your engine from 1966 is likely to be a short stud block without the holes. Here is the gasket on my long stud engine ( identical to an XJ6). As you can see there are no long slots in the gasket but 2 holes which correspond with each slot



The gasket on mine is a modern type with the built in sealant around each water passage, but essentially it is just the same as yours which looks perfectly usable to me

[Alty Ian]

Hi Mats

The gasket that is correct for your 1966 4.2 engine is shown below.



Although as Chris says the later gasket would "work" I have my doubts that the engine cooling would be quite as efficient with reduced waterways and the increased resistance caused by the gasket having smaller holes.

I would get the correct one. Another things you MUST do is add a thin layer of wellseal or similar sealant around the front of the head gasket where it goes round the timing case in particular. I didnt and had to take the head off after 1500 miles to stop an annoying oil leak.

Ian

[christopher storey]

Interesting what you say about water flow restriction, Ian . It occurs to me that on the long stud blocks , which as we can see have a gasket with holes rather than slots in, the water pump is likely to be of the later type with the larger impeller and , presumably, greater pumping capacity so that the restriction may be deliberate. Therefore, on reflection I think that what I said about my later type of gasket being usable on an earlier block is probably wrong and that as you have already suggested it is wiser to use the earlier design of gasket

[Quattrofrank]

But what reason could be behind making the gasket restricting the waterflow?
WHen using long stud block, maybe the best thing is to use the older gasket with the correct water channel opening and just drill the two holes missing?

Having small round holes when the block and head have bigger openings seems uncorrect. This will only collect debris and restrict waterflow.

[Gfhug]

Some gaskets have larger and smaller water passage holes. I was told this was to have a lower flow around the cooler inlet side and give a greater flow around the hotter exhaust side. Certainly the gasket for my S2 is like that.
Geoff

[66an]

Thank you all, I will order a new gasket with oval water holes.
Different hole sizes for the water in a head gasket can be used to adjust the water flow in order to keep the same temperature for each cylinder. The smallest holes are then closest to the water pump where it is the highest water pressure. But that seems not to be the case here.
I am aware of the risk of oil leakage around the timing chain. The recomendation on this forum is to use Hylomar or Wellseal. I am not familiar with those brands, are they silicon sealants? I count to 4 different sealants of other brands in my garage

[Alty Ian]

No they are not silicone. Wellseal was developed by Rolls Royce, its quite liquidy and needs to be applied to all 4 surfaces and left 10-15 mins to go tacky but you dont need much. Seems to work really well.

[Heuer]

Wellseal was developed by RR to seal the faces of two accurately machined parts avoiding the need for a gasket. I am not sure it is recommended for use on the interface between two parts that are not machined to either RR or CNC standards. Always concerned me using it on Jaguar engines from the 1960's but others may have more confidence.

[Quattrofrank]

I always use this stuff http://www.victorreinz.com/EN/Products/ ... PLAST.aspx
Works very well, but its alot of other suppliers with similar products that probabl works as well.

[PeterCrespin]

As someone almost guessed, the hole variation is to control water flow and pressure but side-to side, not front to back. The narrower outlets on the inlet side serve to slightly increase pressure around the combustion chamber 'skulls' and decrease the chance of localised hot-spot boiling.

As for overall flow related to water pump distance, Norman Lutz from Australia has done quite a bit of work on the XK and V12 engines and the Jan-Feb issue of JJ will have a story about this.

Pete