7 replies to this topic

[foggy]

I am possibly thinking of doing this as i have a spare 1275 head, and it's looking like my current 998 head may have some problems, so i am contemplating putting my spare 1275 head on. Can anyone tell me if theres any extra work i need to do? And also which gasket would i use? I presume a 1275 gasket would be needed.

It's got twin SU's and an Lcb exhaust manifold.

Cheers :)

[Turbo Phil]

You need to use the 1275 gasket. To provide clearance between the ex valves & the block face at full lift, you have two options. You can either "pocket" the block or sink the ex valves into the head by machining the seat deeper. Either option will work, & though not ideal, the second option does require less work.

Phil.

[Cooperman]

As Phil say, plus you need to measure and calculate to establish if the compression ratio will be correct and machine the head to get it right. Only then can the valve to deck clearance be checked to see how much the valves need to be 'sunk' into the head or how deep the pockets in the block need to be. If the block id pocketed the engine will need to be stripped right down. If you have a standard cam, then it may be that the valves will not need sinking or the block pocketing, but you won't know until you accurately measure and calculate everything.

[foggy]

Thanks for that, not just a straight forward bolt on job then.....Food for thought

[madaboutcherry]

I,ve been looking into this for a while and think I,ll start looking for a suitable head. one more question though, won,t the exhaust rocker angle be wrong if you sink the valve?

[foggy]

If your interested in a head i have a 1275 metro head i bought off a guy on here.never fitted it myself.but if your interested pm me.

[Cooperman]

I,ve been looking into this for a while and think I,ll start looking for a suitable head. one more question though, won,t the exhaust rocker angle be wrong if you sink the valve?

It might be an issue with a competition engine, but remember you often have to skim 0.050" from the head face which also effects the rocker angle. It's not that absolutely critical and a 0.040" valve sink will still be within valve/rocker angle tolerances.

[Cooperman]

Thanks for that, not just a straight forward bolt on job then.....Food for thought

No, as with all engines and engineering in general, accurate measurements and calculations followed by correct machining is necessary for the right result. That's why professional engine building is never cheap if done properly and why cheap engine building seldom gives a good end result.