4 replies to this topic

[chandler]

What is the difference between a 1275 A and a 1275 H, Is the H for 'Leaded' Petrol? If so, do i have to change the valves?
Thanks Chad

[Guess-Works.com]

12A engines are 90's onwards as fitted to the RSP cooper first of all...

12H engines are those from older 1275 minis ( ie the 1275 GT ), metros or other BL varients...

All 12A* engines are unleaded, however some 12H engines are also unleaded

This is why I built an engine number decoder...

http://www.guess-wor...Tech/engine.htm

It should be noted that the engine number is just the specification of the engine when it left the factory... the head is the key to whether it's unleaded or not.. this could have obviously been replaced without changing the engine number..

To check to see if a head is unleaded you'll need to remove an exhaust valve and look for the hardened seat, if there's no apparent seat then assume it's not converted for unleaded petrol.

Edited by Guess-Works.com, 31 October 2010 - 04:32 PM.

[chandler]

Thanks for all your help, I have a 1990 Mini Cooper with a 12A engine that I replaced with a 12H as the 12A wasn't good. The 12H engine came from an Allegro all original.. I think the Allegro engine is 'Leaded' and I have been running it on 'unleaded' and now I may have blew the valves.

So do you think I will need to put the head from the 12A onto the 12H Allegro engine??????

12H 899AA- 110642

Thanks Once again, Chad

Edited by chandler, 31 October 2010 - 06:21 PM.

[bmcecosse]

Yes - that will be fine. But as long as you look after the valve gaps - and I suggest 15 thou for the exhausts - they run fine on unleaded fuel, no matter which head is fitted. just check/reset the valve gaps every 3000 miles or so.

[chandler]

Thanks once again for all your help much appreciated!!!!

Chad

Edited by chandler, 31 October 2010 - 06:29 PM.