ausmini
https://www.ausmini.com/forums/

Rescued 12G295 head, Thanks GR
https://www.ausmini.com/forums/viewtopic.php?f=2&t=93748		 Page 1 of 1
Author:  68Rusty [ Mon Sep 12, 2016 9:09 pm ]
Post subject:  Rescued 12G295 head, Thanks GR
Just wanted to share work I have had done on 295 head which cheap valve let go on. I can't express enough don't buy none race valves if you are planning on running large cam and double or high compression valve springs. I was told the original valves I bought would be ok which was bad advice which has now cost me a complete rebuild. I have had the head with Graham Russell for some time and got it back today and all is looking good, Graham said he would look after me with this PITA broken valve episode I have had and he did. To make situation worse the head shop I had do the valves in last sunk the seats so much lower then they needed to be it almost binned the head but GR has fitted the new small bore race exhaust valves with seat inserts and gone a bit custom on the inlet to extend more life out of the head.

See pics below of head when valve let go,
Image
Image

Pics of head with all the good bits, I asked GR to fit single valve springs in to get me to 6500rpm only as I have no intention of going higher then that with 1100 crank. I think the double valve springs commonly used at 200pounds are far to strong but many people use them so seems maybe just my opinion but I am happy with the force of these singles now on the head.
Image
Image
Image
Image
Author:  deluxe67 [ Mon Sep 12, 2016 9:28 pm ]
Post subject:  Re: Rescued 12G295 head, Thanks GR
Looking at your pictures there was more stuff wrong than just a valve failure....
Author:  68Rusty [ Tue Sep 13, 2016 5:50 am ]
Post subject:  Re: Rescued 12G295 head, Thanks GR
deluxe67 wrote:
Looking at your pictures there was more stuff wrong than just a valve failure....

How do you mean?


Sent from my iPhone using Tapatalk
Author:  simon k [ Tue Sep 13, 2016 12:17 pm ]
Post subject:  Re: Rescued 12G295 head, Thanks GR
68Rusty wrote:
deluxe67 wrote:
Looking at your pictures there was more stuff wrong than just a valve failure....

How do you mean?


maybe the oily soot in the next chamber and the rusty gunk in the water jacket?
Author:  68Rusty [ Tue Sep 13, 2016 12:54 pm ]
Post subject:  Re: Rescued 12G295 head, Thanks GR
simon k wrote:
68Rusty wrote:
deluxe67 wrote:
Looking at your pictures there was more stuff wrong than just a valve failure....

How do you mean?


maybe the oily soot in the next chamber and the rusty gunk in the water jacket?

When the valve dropped and punched hole in piston pulled oil into number 2 through inlet manifold. It actually pulled pieces of the smashed valve guide in to number 2 as well.

I shut it down and put clutch in as quick as I could but happened very quickly!


Sent from my iPhone using Tapatalk
Author:  simon k [ Tue Sep 13, 2016 2:14 pm ]
Post subject:  Re: Rescued 12G295 head, Thanks GR
68Rusty wrote:

When the valve dropped and punched hole in piston pulled oil into number 2 through inlet manifold. It actually pulled pieces of the smashed valve guide in to number 2 as well.

I shut it down and put clutch in as quick as I could but happened very quickly!


same thing happened to me a few years ago - my MK2 head looks a lot like yours did, maybe a little worse... we reckon the valve seat insert dropped out and stuck the valve open

I should get GR to have a go at it
Author:  drmini in aust [ Tue Sep 13, 2016 3:23 pm ]
Post subject:  Re: Rescued 12G295 head, Thanks GR
I have a 1275 head that did the same, it totalled the insert and beat up the chamber and inlet seat. I welded the insert recess right up with nickel electrode, GR is going to machine it for one of his inserts which are smaller OD.
Author:  slide [ Tue Sep 13, 2016 6:10 pm ]
Post subject:  Re: Rescued 12G295 head, Thanks GR
Is seat inserts falling out a reason for not converting a head to unleaded? How common is this on converted heads?
Author:  simon k [ Tue Sep 13, 2016 6:24 pm ]
Post subject:  Re: Rescued 12G295 head, Thanks GR
slide wrote:
Is seat inserts falling out a reason for not converting a head to unleaded? How common is this on converted heads?


dunno how common it is, but I don't think it's a reason not to have it done, I think it's a reason to make sure they're done by someone who knows what they're doing and that your car is running right.

Mine happened on the first long drive after I'd put a supercharger on my motor and I think it was running much too lean, to the point where heat expansion in the head & seat were too different and the seats loosened. The other seats show similar signs of not wanting to stay put. It could also be that the bloke who cut the seats for the inserts made them a bit too big with not enough interference fit, dunno at this point. My current head went on to the next build of the supercharged motor without seat inserts, then when I rebuilt it the seats were rooted so I had inserts put in. I had the head off a few months ago and they looked fine

My dad's 1275 Minor has had exhaust seats in it since the early 90's...
Page 1 of 1 All times are UTC + 10 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/