Large Bore Head Gaskets

[pad4]

Interesting - especially as we have a flatbed cnc router at work

What grade of copper are you using ?

Pad

[Spider]

I used to have solid copper gaskets made and fit them on a few comp cars back in the early 80's. Completely reusable, only they need to be annealed between uses. We didn't do anything special for a flame ring in them at that time, however I think some of the other guys were doing as 850man is.

Ha, I found out recently that our local Aluminuimn supplier does these (he races also);-

http://www.obrien-aluminium.com.au/gasket_1.html

[minicentie]

In the spec of your engine ,i can't find the piston size and if they come up close to the deck?
If you torque the head,the gasket will expand into the chamber,a bit.
When the piston is near the deck,it can hit the gasket and give it a short life.

[ianh1968]

Update:

Thank you all for your replies. Some very helpful ideas/comments...

Unfortunately, the ally head has met its demise at the machine shop. I had
promised myself that the next time that head came off, it would get a new set
of guides and have a tidy-up skim as it's several years old now.

OH SH!T
Stepped guides = Trashed head (If you push them out from the top)
Something to remember for next time!

WARNING TO ALL:

The 5-Port Ally Head, casting No. 16219M has guides which are about
0.466" diameter on the bit that you can see, and 0.437" on the size
that goes into the head bore...

The head may be salvageable but would require quite a bit of work which
would involve some bespoke machining etc. Then again, I could get the
head sliced up on a powered hacksaw to get some idea of where the
water-ways are...

Short term, I've installed a modified iron head on the engine. It all starts
to get a bit complicated as I have 2 cars. Both of my ally heads had 16cc
chambers and on the Mini this gives about 13:1 C/R which is way too high
for a 276 degree cam. I'll be getting replacement ally head and will cut
this with bigger chambers and it will go on the Mini. The head currently on
he Mini will go on the Marcos. The iron head on the Marcos will then go
back in the loft.... It's a game called "Musical Cylinder Heads"

I have started another related thread.

Ian

[Spider]

Thanks for the update and a real shame / bugger on the guides. Who would have thought???

Could you machine the guide holes a little larger and fit oversize guides? Be a shame to waste the head just for that. Hope it runs better and more reliably for you this time around.

[251 ENG]

Do you want to sell damaged alloy head ?

[ianh1968]

Do you want to sell damaged alloy head ?

You have PM...
Ian

[ianh1968]

Do you want to sell damaged alloy head ?

You have another PM
Ian

[jdm]

Simple repair to your 5 port alloy head as I have just completed one on an 8 port Gordon Allen/ Pinon head, Buy a set of VW Polo valve guides which are 7mm bore by 12mm outside diameter and same length as a mini guide. Ream the guides 9/32 inch and have the head guide bores reamed to 12mm and re cut the seats.

jdm

[vegar]

Simple repair to your 5 port alloy head as I have just completed one on an 8 port Gordon Allen/ Pinon head, Buy a set of VW Polo valve guides which are 7mm bore by 12mm outside diameter and same length as a mini guide. Ream the guides 9/32 inch and have the head guide bores reamed to 12mm and re cut the seats.

jdm

Those Polo-numbers are the same as Fiat FIRE. Another cheap source of guides

[vegar]

I had this happened to my Morris

[Spider]

Bugger there vegar.

Looking at that, if I may suggest, check that the ignition timing is optimised, it appears that it may be retarded at certain RPMs.

[John Bull]

Simple repair to your 5 port alloy head as I have just completed one on an 8 port Gordon Allen/ Pinon head, Buy a set of VW Polo valve guides which are 7mm bore by 12mm outside diameter and same length as a mini guide. Ream the guides 9/32 inch and have the head guide bores reamed to 12mm and re cut the seats.

jdm

So now you know where to get guides for when we do the head I've just removed.

For those who don't know him, John -JDM - has been a Mini man for as long as I've known him - close on half a century, and he does most of my engineering work. He is presently replacing valves and guides on one of my 8 port heads.

Thanks John.

[vegar]

Bugger there vegar.

Looking at that, if I may suggest, check that the ignition timing is optimised, it appears that it may be retarded at certain RPMs.

Thanks for the advice. I will check when I have the car back together. Life just seems to get in the way....

[Spider]

Simple repair to your 5 port alloy head as I have just completed one on an 8 port Gordon Allen/ Pinon head, Buy a set of VW Polo valve guides which are 7mm bore by 12mm outside diameter and same length as a mini guide. Ream the guides 9/32 inch and have the head guide bores reamed to 12mm and re cut the seats.

jdm

Those Polo-numbers are the same as Fiat FIRE. Another cheap source of guides

I haven't looked for myself yet, but I'm told that some of the Honda V-tec guides are also an option.

[John Bull]

Here's a pic of your 2 Maltese forum members, John Drury - "JDM" - he's the tall one, and myself "John Bull" at a hill climb in Italy in 1980. Coincidentally this was also my first win in Italy - at the Giarre Montesalice Hill Climb to be exact, driving my red and white Group 5 1300. Other Minis in the pic - friend Roger Calleja's red Group 2 1300, and my gold 66 Austin Cooper S tow car.