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Head question
https://www.ausmini.com/forums/viewtopic.php?f=2&t=20238		 Page 1 of 1
Author:  EST-071 [ Sat Jun 17, 2006 10:44 am ]
Post subject:  Head question
I have just pulled down the head on my motor. It is a 12g940 with standard sized valves. The question I have is did they come standard with exhaust valve seat inserts? And how can you tell if they are for unleaded or not?
Cheers Pete
Author:  Drekkus [ Sat Jun 17, 2006 11:07 am ]
Post subject:  Re: Head question
deluxe_68 wrote:
And how can you tell if they are for unleaded or not?
Cheers Pete


A magnet ?
Author:  Mike_Byron [ Sat Jun 17, 2006 11:17 am ]
Post subject: 
What is the motor out of - I am led to believe that only A+ 1275 s had unleaded inserts.

I think you would see a ring around the outer edge if the inserts had been done.
I wanted to have unleaded inserts put into my 12G940 head and my local engine reco man refused to do them as he felt that some of the insert would be in the heat of the explosion and some of it would not be. He felt there would be a danger that the insert could distort and fall out. This same engineer has happily put inserts into small block heads of mine.

Having said that - Doc and a number of others on here have had big bore heads fitted with inserts and had many many kilometres of trouble free motoring that included track days and the like. Its an area of controversy.
Author:  EST-071 [ Sat Jun 17, 2006 11:29 am ]
Post subject: 
Mike, thanks for that. I don't think it is an A+ as it also has 12g938 stamped on the thermostat housing. There is also a ring around the seat as if they have been put in after the factory.

Drekkus, how can you use magnet to find the difference?

Pete
Author:  simon k [ Sat Jun 17, 2006 11:29 am ]
Post subject: 
I have all of my 12G940 heads fitted with hardnened seats (inserts) - never had a problem with them.... I have an old head AEG163 that someone used without them and it's rooooted - reconditioner says its unfixable - the seats are just too far gone to do anything with

if it's an aussie head (non A+) then it wouldn't have had inserts standard

if the head is unknown, then you should have it cleaned up, crack tested and get new guides fitted anyway, then you'll know whether or not it has seats, if it doesn't have hardened seats, get them done.... all that work by my local reconditioner costs me $270 - bargain ;)
Author:  simon k [ Sat Jun 17, 2006 11:33 am ]
Post subject: 
deluxe_68 wrote:
Mike, thanks for that. I don't think it is an A+ as it also has 12g938 stamped on the thermostat housing. There is also a ring around the seat as if they have been put in after the factory.

Drekkus, how can you use magnet to find the difference?

Pete


12G938 is an 1100S head, small valves

the ring around the seat is probably the insert - hit it with a wire brush and clean it up and you'll find it's a very different sort of metal
Author:  EST-071 [ Sat Jun 17, 2006 7:08 pm ]
Post subject: 
Also what is the best way of getting all of the carbon out of the ports?
Pete
Author:  drmini in aust [ Sat Jun 17, 2006 7:16 pm ]
Post subject: 
What looks like a ring around the seat is often just the spotfacing they did during manufacture.
Only way to tell is pull an exhaust valve out, and wire brush inside the port. If it has inserts you should be able to see then.

Another way to tell (if Rover unleaded seats, anyway) is put a Mini sump plug magnet on the seat's angled face. if it sticks, it's the original cast iron head- if not, it has non-ferrous or austenitic inserts.
This test is not infallible as some reconditioners use 4140 steel inserts- and they ARE magnetic.
Author:  Mike_Byron [ Sat Jun 17, 2006 7:19 pm ]
Post subject: 
Depends on what you want to do with the head. If your taking it to a machine shop then they will hot dip it almost routinely and then its spotless.

You are advised to do this as they will check the valvle guide clearances but more importantly they will skim the head. Well over 60% of all mini heads are warped. They will also reface the valves and valve seats.

Therefore, carbon in the valve seats is not a major problem. However, if your not going to take it to a machine shop then the best way is with a die grinder with a wire wheel attached. Take out the valvles first. Brake cleaner (in a spray can) also helps.
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