1275 Head Question

[mickm]

A pal has a 12g 940 head that he is going to fit to the 1098 midget engine in his moggy, it is the small intake valve version from a "classic" mini. His questions are; are these heads suitable for unleaded and roughly how much metal would need removing from the top of the bores for exhaust valve clearance when using the standard MG camshaft and cast rockers.Thanks in advance.

[bmcecosse]

Well - it likely won't be an 'unleaded' head as such - but can be used on unleaded without any worries - just set the exhaust valve gaps at 15 thou - and check/reset them every 3000 miles. He needs to measure the height of the face of the exhaust valve from the face of the head. If it's 320 thou - then nothing needs doing. If it's any less - the easiest thing to do (by far!) is to sink the valve(s) into the head until the 320 thou is obtained. This is fine up to ~ 40 thou - but often 20 thou will be sufficient. Any machine shop can do this is minutes - I used a pillar drill and a largish 45 degree countersink. He must also re-align (add washers/some filing) the rockers on the shaft so they act DIRECTLY over the tips of the valves - and probably need to file some metal off the top edge of the water pump to make sure the head can sit down on the block without fouling. It is a VERY worthwhile conversion using this head on a 1098!

[mickm]

Thanks very much for the information Roy I will pass it on!!. Mick

[Matt]

If the head is from a 90's car it should be unleaded. If not I would advise using an addative - especially if he is doing high mileage or thrashing it!