Just an idea for later in the year maybe. Boris has a 1275 Marina engine fitted but also in my stocks of bits n bobs n rubbish I have a 12G940 A series head (of off a 1300GT i'm sure). It's the large valve type with twin valve springs but also 11 stud (well 10 + 1 bolt) so the 2 extras wouldn't have anything in them.
I will be using the head later on it's original engine in my mini but thought I might get some benefit from it by fitting it on Boris for now.
Would this fit ? Would there be any improvement ? is there any point ?
1275 Head Swap
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philthehill
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Re: 1275 Head Swap
A good number of 10 stud and one bolt heads have been converted to pure 11 stud heads at some time my own head/block included.
The only proviso when converting to 11 stud is that the 11th stud is not tightened any more than the original torque for the bolt as there is a risk of breaking it out of the block as the casting thickness in the area of the 11th (front) stud/bolt is quite thin and that is why the smaller diameter bolt was fitted at a reduced head torque of only 25 ft lb.
9 stud 940 heads can be converted to 11 stud specification with very little difficulty as there is a casting web at the front and rear of a 9 stud 940 head that can be drilled right through using the head gasket as a location template for both head and block.
The only proviso when converting to 11 stud is that the 11th stud is not tightened any more than the original torque for the bolt as there is a risk of breaking it out of the block as the casting thickness in the area of the 11th (front) stud/bolt is quite thin and that is why the smaller diameter bolt was fitted at a reduced head torque of only 25 ft lb.
9 stud 940 heads can be converted to 11 stud specification with very little difficulty as there is a casting web at the front and rear of a 9 stud 940 head that can be drilled right through using the head gasket as a location template for both head and block.
Re: 1275 Head Swap
As I'll be putting the original head back I doubt I'll get the block drilled n tapped for the extra bolt and stud. As long as it'd be ok to do that (or rather not to !!)