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Cylinder head repair - Opinion's?
#1
This is a repair completed on a '71 429cj cylinder head, sorry, I don't know if it was intake or exhaust port off hand... I understand there is a way to address certain cracks in heads in order to salvage them when they are rare, #'s matching, etc., I believe the process involved drilling and plugging (at the base of the crack) and then welding to prevent the head from further cracking... This is the type of repair that was was done on this particular cylinder head. From an engine rebuild expert opinion (if you qualify yourself as such Smile, was this a good repair? Curious as to "those in the know"... and their thoughts. Thanks


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#2
We did some repairs in the race shop I was in due to high cost of parts to poor racers, lol.
We even brazed the thrust bearing web back in a side oiler 427. When NASCAR cars hit wall the crank shaft goes forward and usually destroys block.
It looks like I see signs of peen marks to the right in the picture. When you weld cast iron you peen the weld and around it to expand the metal so it does not crack again. So that part would be right. We did not put plug in at the end of crack but drilling at end is common.
I have sent stamping dies that broke and had them welded and brazed back together at MPD welding in Michigan. You might give them a shout and that is all they do. They know exactly the right way.
I went and watched them weld one die for 3 days around the clock. Sits on big heat table and after all welding and brazing is gradually cooled off to prevent cracks also. It formed the Ford Ranger extended cab inside back and broke into 4 pieces due to hitting more than one part. It fell out of the press. The die ran for years after welding with no quality issues.
Use to weld lots of flathead Ford blocks. They have much better weld rods and equipment today than back then also.


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David
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#3
(03-31-2019, 10:34 AM)Carolina_Mountain_Mustangs Wrote: We did some repairs in the race shop I was in due to high cost of parts to poor racers, lol.
We even brazed the thrust bearing web back in a side oiler 427. When NASCAR cars hit wall the crank shaft goes forward and usually destroys block.
It looks like I see signs of peen marks to the right in the picture. When you weld cast iron you peen the weld and around it to expand the metal so it does not crack again. So that part would be right. We did not put plug in at the end of crack but drilling at end is common.
I have sent stamping dies that broke and had them welded and brazed back together at MPD welding in Michigan. You might give them a shout and that is all they do. They know exactly the right way.
I went and watched them weld one die for 3 days around the clock. Sits on big heat table and after all welding and brazing is gradually cooled off to prevent cracks also. It formed the Ford Ranger extended cab inside back and broke into 4 pieces due to hitting more than one part. It fell out of the press. The die ran for years after welding with no quality issues.
Use to weld lots of flathead Ford blocks. They have much better weld rods and equipment today than back then also.

Thanks David. This was sent to a specialized shop that knows what they are doing... My engine builder was quite thorough in examining my original 429 cj engine during the rebuild. He only works on one engine at a time... The heads, including this one are original to the car... The engine was rebuilt probably at least twice before and run many hard miles..., so I had to make some decisions when it came time to rebuild the original #'s matching engine. The two main issues were the already 0.40" overbore and a lesion on one of the cylinder walls that was too deep to risk attempting pushing the bore larger and not have heating and cooling issues down the road. So, we made the decision that all the cylinders were re-sleeved and brought back to standard bore. The second issue was this small crack my builder found, but he was confident that it could be repaired properly as he knew the right guy to send the head to. 45 years and hundred's of thousands of miles later, we cannot expect virgin parts today... If this was not a rare and #'s matching car, I would have went out and found a replacement head, but i wanted to keep the original part. So far, she run's like a champ Smile
[Image: Restored-429cj-block-sleeved3-2.jpg]
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