Morris Minor Owners Club

been meaning to do this for years now, but i am going to convert primrose to unleaded.

would i be able to replace the valve seats by myself or would i need a workshop with presses etc?

Don't bother - there really is NO need! Just run it on unleaded - set the exhaust valve gaps to 15 thou, and check/reset them every 3000 miles. No need for additives either........ And NO - you cannot fit valve seats yourself.

ah right, cheaper and easier

In my opinion you might as well keep your standard head until if or when it is knackered then exchange it.

With a standard (ish) engine it is worth trying without converting; if you end up constantly opening up the exhaust valve tappet clearances, not the inlets as these are not converted to hardened seats, then that tells you it needs converting. There is only so much valve seat recession that can be allowed before you will be forced to convert!

What are you doing now, using an additive?

With a modified engine, I would not risk doing nothing - either use an additive with the on-going cost, or bite the bullet and get it converted (this is not a DIY job at all, and the cost is likely to be £100/150). Unleaded fuel burns slower and hotter, which a modified engine just amplifies.

Try without first and monitor the tappet clearances - Roy's suggestion to open up the exhaust from the standard 0.012" to 0.015" is a good one (assuming you have a cam that uses the standard clearances), as it gives a bit more latitude before the tappet clearance closes up to become a problem. The 'normal' behaviour is for them to open up slightly with wear, so if they close up, that is through 'valve seat recession', i.e. it's wearing away slowly! Worth a try.

What is your engine spec and what sort of annual mileage does it do?

MG/Rover opened up the clearances on later engines anyway.......
And if you 'really' want to unleaded - look out for a factory unleaded 940 head - and fit that, gaining useful power in the process!