7a crank

[Quattro Dan.]

Will the 7A crank just bolt straight in to a 3b block using 3b pistons and rods?

Also can people suggest possible reasons for my 3b crank seizing. New head gasket, head skimmed and checked, new water pump, rad ok, oil pressure 5 bar, driving along and engine cut out and steam came out of the header tank at the same time. I have removed the timing belt and tried to rotate the crank on the pulley bolt but it appears to be seized.

Thanks, Dan.

[220bhp]

what makes you think the cranks broken.

[driftin jo]

Will the 7A crank just bolt straight in to a 3b block using 3b pistons and rods?

Also can people suggest possible reasons for my 3b crank seizing. New head gasket, head skimmed and checked, new water pump, rad ok, oil pressure 5 bar, driving along and engine cut out and steam came out of the header tank at the same time. I have removed the timing belt and tried to rotate the crank on the pulley bolt but it appears to be seized.

Thanks, Dan.

It sounds like it could be piston to bore seize, I'm not saying I can't be seized on a bearing but it is less likely especially as you have the steam thing going on !

Who did the head gasket ? Was it torqued in the correct sequence ? If not the it would not sealed properly .

[Quattro Dan.]

I did the head gasket, i have done at least 10 of these and they have been fine.

[driftin jo]

How much was taken off the head when it was skimmed ? if you have raised the compression too much you may have been getting pre ignition, this could have caused a piston to seize.

[stiglet]

As far as I can tell, all the 5-pots apart from the NM have the same crank part number. So should be a bolt on swap anyway.

[spink]

they are the same physical size etc but the 7a's have oil drain holes drilled through them at different angles,or at least certain age 7a's do.There is a thread on here about it (2+ years old)