Why you should crack test before hand and save three days!!!!!!!!!!
Turbo Mini Forums

Not that I neglected to inspect the head before I started the porting and shaping, but part way through the stone grinding phase I noticed the dust tracking in an all to familiar way on the adjacent chamber. It was obvious what I was seeing so I finished the head seeing as I only had two chambers left to do to complete the job then did a crack test.



This is what was found



And this



The question is what to do next. There are three distinct approaches to this.

1. Cold stich the crack
2. Cut out the crack and get it welded
3. Remove the crack with new valve seat inserts.

Now three is the less likely option as I dont know how tall an insert you are limited to. Welding I could do myself with the aid of several blow torches. Stiching is a bit of a black art and a new process to me.

What are the thoughts of those in the know?

Edit: if larger pictures will help can be done

Edited by Mr Joshua on 4th Aug, 2009.

Own the day

ive succesfully welded crack in that area,,

as you suggest, grind a prep , get it almost glowing hot with the bottles and stick weld with dissimilar rods.

theres no reason why it cannot be salvaged.

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Yes i've had a cracked head welded there and if done right it can last.

Best 1/4 mile 13.2 seconds @116 mph
First 5 port miniturbo to make over 200 bhp on a carb?
First 5 port miniturbo to make over 200 bhp on Injection?

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What size valves where in this head when you started ?

mmmmmmm raspberry jam

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

the other thing you could do mate is have 8 harden seats fitted.

Best 1/4 mile 13.2 seconds @116 mph
First 5 port miniturbo to make over 200 bhp on a carb?
First 5 port miniturbo to make over 200 bhp on Injection?

http://www.mattwoodsphotography.com

One thing to remember. If you weld the crack, then have it machined for inserts. This WILL be a total bitch, as the weld is so much harder than the adjacent iron.

I'd bin it without a doubt, and believe me, I've been in the same situation several times.

This was an unmodified MG metro head 35.6mm inlets and 29.2 exhausts.

I hear what your saying Vegard but I have 3 of 6 heads cracked, as is the realisation these heads are becoming hard to come by so a solution to this type of failure is needed before too many more are consigned to the skip.

I am also lending towards cold stitching as Beachgrove engineering has done this successfully on some historic racing car engines and later model Fords (cortina's).

Own the day