Cracked heads

Alan Stanley · Post by **Alan Stanley** » Sat Mar 24, 2007 10:17 pm

What is the latest thinking on repairing cracked heads?
Welding, inserts??
Anything need to be careful of?

Alan Stanley · Post by **Alan Stanley** » Sun Mar 25, 2007 2:55 am

A Club member went through all the heads in our parts shed, maybe 20 or so the other night and all were cracked hence the question still stands in the situation here.

Keith Andrews · Post by **Keith Andrews** » Sun Mar 25, 2007 6:36 am

Alan ring Eddie of
Takanini Cylinder Head Specialists Ltd
09 298 3355
4/197 Gt South Rd Takanini Auckland

You may have to take a set down for him to look at...
Front there he will piont u in the right direction
Then will finish the machining.

Post by **Forumadmin** » Tue Mar 27, 2007 12:15 am

I have had two heads with cracks repaired through Mike Smailes. Having unleaded inserts would probably cure most cracks. I recommend everyone reads the articles in the JowettGallery compiled by Mike Allfrey.

Srenner · Post by **Srenner** » Fri May 04, 2007 4:43 pm

Hello all!

I have been racing my Jup on repaired heads since 1991 and have not had any problems.

Heads were placed in an oven until hot, cracks were "pinned" by inserting small "spikes" into the pre-drilled cracks. After everything cools, the pins are ground down, seats inserted and the rest is just a valve job.

There is no real trick, just a good machinist who knows what to do.

Cheers!

Alan Stanley · Post by **Alan Stanley** » Fri May 11, 2007 11:45 am

Scott I assume you have inserts pinned in, although you make no mention of it. I have had bad experiences with inserts and that is why I asked the original question, to inert or to weld??

Keith Clements · Post by **Keith Clements** » Fri May 11, 2007 3:15 pm

I have had three sets done. two have been rallied. No problems. The inserts were secured with small Allen set bolts on the circumference.

Srenner · Post by **Srenner** » Sat May 19, 2007 4:34 am

If I understand your question properly, the seats are pressed in at a specified "fit". I would have to call the machinist and ask what that is. For example, it could be .002", where the seat or insert is that much larger than the opening into which it is being fit.

I have never had a seat come out, although I have seen that happen, with pretty devastating results.

On some of the heads I have had done, after the crack is repaired, the seat area is cut and the seat pressed in, covering some of the original crack area and, therefore, some of the repair. Since the seat is a harder material, it won't crack and sort of "spreads the load" around the area into which it is pressed. In my heads, I do not think the seat was held in by pins, but I have seen other heads (other makes) where they had been peened in a couple of spots.

Once again, I have to say I think it is the skill level of the machinist that makes the process work.

I hope this has been of some help. By the way, I do have some bare, uncracked heads. Shipping weight is about 50lbs per set.

JowettTalk

Cracked heads

Cracked heads

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Cracked Heads