Discussion
Tough one this - Stage 3 means different things to different people.
Try looking for the obvious, whether the Inlet & exhaust ports have be opened out and if any replacement (bullet nose) guides have been fitted. The Inlet valve on the standard MG head is 35mm. This is widely accepted as upgrade in valve diameter to a Stg3 large inlet valve (MG Rover chose to do this at the factory). Last thing is the chamber, look for signs of reshaping and then lastly burette the chamber to measure if the cc value has changed (Hihger CR - CC Lowered) as a results of head work and subsequent skimming.
Try looking for the obvious, whether the Inlet & exhaust ports have be opened out and if any replacement (bullet nose) guides have been fitted. The Inlet valve on the standard MG head is 35mm. This is widely accepted as upgrade in valve diameter to a Stg3 large inlet valve (MG Rover chose to do this at the factory). Last thing is the chamber, look for signs of reshaping and then lastly burette the chamber to measure if the cc value has changed (Hihger CR - CC Lowered) as a results of head work and subsequent skimming.
Edited by FWDRacer on Wednesday 28th January 12:21
As FWDracer says, these 'Stage nos' mean very little as each head tuner uses different criteria.
A basic head casting on a Mini is so easy to improve for whatever use you need from a good road-going head to a full race one.
If the combustion chambers have been re-shaped and the surface of the chamber smoothed out to remove all the ridges and rough casting finish, then it has certainly been re-worked at some point.
With the valves fitted and the plugs in, measure the volume of each chamber and post it on here. I use a 10cc syringe from Boots-the-Chemist and a piece of flat perspex with two 1/4" holes in. Lay the perspex over the chamber with the head level and fill the syringe with paraffin. Measure exactly how much paraffin it takes to get all of the air out of the chamber. To give you a clue it will be about 21cc, but you need to know exactly.
What does thhe invoice say has been done to the gearbox?
A basic head casting on a Mini is so easy to improve for whatever use you need from a good road-going head to a full race one.
If the combustion chambers have been re-shaped and the surface of the chamber smoothed out to remove all the ridges and rough casting finish, then it has certainly been re-worked at some point.
With the valves fitted and the plugs in, measure the volume of each chamber and post it on here. I use a 10cc syringe from Boots-the-Chemist and a piece of flat perspex with two 1/4" holes in. Lay the perspex over the chamber with the head level and fill the syringe with paraffin. Measure exactly how much paraffin it takes to get all of the air out of the chamber. To give you a clue it will be about 21cc, but you need to know exactly.
What does thhe invoice say has been done to the gearbox?
Gassing Station | Classic Minis | Top of Page | What's New | My Stuff