Cylinder head question

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ValiantMike

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I called a cylinder head supplier in my area and asked if they could mag my heads to check for cracks and the guy told me that they pressure test heads instead. Is this a safe way to go, or should I find another shop? Thanks Mike
 
There train of thought must me that even if the head has a crack and if it doesn't leak then it is OK. I will tell you that I have in the past run heads that had small cracks between the seats, because of the valve size it was very narrow and they cracked. There was no water between the seats so they did not leak and ran fine. This was OK in this case because the heads I am talking about, this was common to happen. I actually installed a new set once that had no cracks but upon tear down at the end of the season it had two seats that were cracked I never would have known until I tore it down. I have not heard of Mopar heads having this problem so I probably would not, at this time, run a Mopar head cracked. The cracks I was talking about were visible to the naked eye so magging was not nessesary but I did have them pressure checked. Magging is really for picking up non-visible cracks like on cranks and internal parts that a hairline crack could go unnoticed to the naked eye. Every block or head crack I have ever seen even by magging was still visible by the naked eye. The bottom line is you should do what gives you piece of mind. I myself have no issues running a cracked head in some situations but for others it is a no-way. If you want your heads magged than that is what you should do.

Chuck
 
The only problem with pressure testing heads is that they may seal cold but then the cracks open up when they get hot or at normal operating temp., this is all that they can do for aluminum other than the dye check method but this is for aviation and is rather pricey, and not many shops do this. For iron pressure testing may show a internal leak or a severe crack but then as has been stated you should be able to see the crack if it's this bad.
Most all magnums that I have seen have been cracked, and they are generally on the end cylinders as they get the hottest. Part of this is due to the thickness of the material and the foundry that did them for mopar. Thin light weight casting tend to run hotter and weigh less but they have inherent problems, and cracking is one of them.
 
Well, heres the thing. I started to do a little porting on some 302 heads and the first exhaust bowl I started on showed a line in it and I'm not sure what it is. Before I go any further I want to make sure I'm not wasting my time. I'll try to attach some pics and maybe you guys can give me your opinions. Thanks Mike

familyheads 021.JPE


familyheads 022.JPE
 
Will the other bowls have similar lines like that I can check to see if it consistant? Should I grind those out?
 
The other head may not have them, it just depends on who did the castings. Generally when a 1.60 valve is put in and the bowl is cut on the machine these casting marks are blended in with the 75* cutter and disapear. The thing is that the lines may be further back than what you need to grind when useing the stock size valve.
 
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