Cylinder Head - Need advice

[BugeyeandMini]

I purchased this 948 cylinder head a while back that came off of a H Production Bugeye. My intent was to build my own engine but have decided to purchase one instead. I didn't really look at the cylinder header after I received it, but I have now and I'm concerned about this area around the oil plug hole. It is more than a hole as you can see in the picture and it isn't factory. I don't know if it was done as part of it being modified to a full race prepared cylinder head. I guess my question is is the head okay, will it leak oil?

Thanks for your thoughts.

 

[Bob Claffie]

Lay a gasket on the head and see if there is a corresponding hole in the gasket. If no hole in the gasket essentially that hole in the is "blind". If there is anything in there it has no place to go. Likewise, if there is not a matching hole in the block you're good to go. Bob
Sorry for trying to give a generic answer to a specific question. Not really familiar with those little BMC engines.

 

[nomad]

Agree that it needs to line up with the gasket and the hole in the block since that is your oil feed for the rocker's. Looks like it was done to make the head match a block it was not originally designed for. Weather it will leak to the outside is something you will have to determine by a trial fit. I'd bet some carefully applied JB weld would eliminate any issues. Least that'ed be my baling wire approach!

Kurt.

 

[AN5Sprite]

I don't know, but I'm curious: When I saw that pic I figured that hole was a result of skimming off an extreme amount of metal to raise compression. 16:1 or something like that? In other words, not really a good choice for a streetable 948???

 

[BuggerAll]

On 948 and 1098 heads, the oil passage to the rocker shaft is pretty close to the head surface, and when you mill the head down for increased CR, the passage ends up exposed. What we used to do (back when I ran a 1098 G prod car) was mill out the exposed passage, then braze in a piece of brake tubing, then mill the head flat again and carefully drill the installed tubing so that the oil hole from the block lines up, and the passage up to the rocker shaft is clear also.

 

[Spridget64SC]

Like Mac says, for the 948/1098 full National race heads, they almost always opened this oil passage. Another fix was to braze up the area where the fire ring would sit and lightly re-surface the head. Then mill the slot completely open from the point that the head gasket hole lines up to just outside the fire ring. Then mill a new slot from the old slot to the front tall head stud hole. Let the oil go up around the head stud and through the stud hole in the head. Mill a slot from the stud hole to the old oil hole on the front rocker pedestal pad and the oil gets to the rocker assembly.

If you do use the head, make sure the oil passage is open.

Making some repairs to an old Comptune 948 head myself and it needs a re-braze of the area under the fire ring.


Mike Miller
Comptune