Magna-fluxing found a Crack in one of the heads

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greymouser7

greymouser7

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The machinist found a crack in the cylinder head I have after magna-fluxing them.

One of the guys answering the phone says it is a crack directly connecting the two valve seats -in between them, connecting them.

Is it worth paying to pressure testing them, can they be repaired, is it worth replacing them?

Does a pressure test not incorporate the dynamic stress of heat & combustion cycles?

Would you continue to have the head pressure checked or just look for another set of heads?

Is there another 360 cylinder-head serial number that will match-up (combustion chamber/-I/E runners) with the good 4071051 head that I have in the shop?

these are stock heads going to a street 360, A833, F-body with a mild cam:

Lunati 10200301, 275/275 477/477 STREET MASTER HYDRAULIC FLATTAPPET CAMSHAFT 07401

thank you very much for your time and consideration!
 
Although people run the cracked, I throw them away. Whether they pass a pressure test or not. Cast iron is funny stuff. I never trust it once it cracks. Just one man's opinion.
 
In my opinion once cracked the cast iron will continue to propagate that crack. I would source a new head... No sense in wasting the cash on them performing a pressure test on a bad head...
 
greymouser7 said:
The machinist found a crack in the cylinder head I have after magna-fluxing them.

One of the guys answering the phone says it is a crack directly connecting the two valve seats -in between them, connecting them.

Is it worth paying to pressure testing them, can they be repaired, is it worth replacing them?

Does a pressure test not incorporate the dynamic stress of heat & combustion cycles?

Would you continue to have the head pressure checked or just look for another set of heads?

Is there another 360 cylinder-head serial number that will match-up (combustion chamber/-I/E runners) with the good 4071051 head that I have in the shop?

these are stock heads going to a street 360, A833, F-body with a mild cam:

Lunati 10200301, 275/275 477/477 STREET MASTER HYDRAULIC FLATTAPPET CAMSHAFT 07401

thank you very much for your time and consideration!
Click to expand...

Only one way to do it >

Submersed Pressure Tester.

The Magna-Flux test cannot show the 'non-visible' area of the crack.

We use an 'AXE #UP 1437 Pro Pressure Tester' for all Cylinder Heads. Many Cylinder Heads have heat surface cracks in them, but are 'tight' for pressure.
 
Where is "Location: Itty Bitty Living Space." ? I've got a pair of heads from a mid 80's 360 I'll be selling off when I get into the shed again. Came off a 70k mile engine about 5 years ago and have been under a rag on a shelf in the shed ever since. If you are near Baltimore, make me an offer.
 
John, any 340/360 head will work as well as the cracked one you have. I wouldn't bother looking to see how bad a crack is on one. They're a dime a dozen. Look locally, find one that will work, and have it done to match what you have.
 
When I pressure test a cylinder head. I use a plate that covers the gasket surface and plates that block the ports for the coolant that goes into the intake, then just add 40psi of shop air and apply a soapy mix and look for bubbles. cracks between the intake and exhaust seats don't always leak but they can expand at anytime. I have drilled and tapped holes through the crack and installed special screws called Lock & Stitch. Then you install harden seats in the intake and exhaust this will fix most cracks but it is very time consuming if you can find a head it maybe cheaper. Good Luck
 
69 Cuda 440 said:
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The Magna-Flux test cannot show the 'non-visible' area of the crack.

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Click to expand...


Actually Magnaflux is capable of detecting subsurface defects. I did it for several years in the piston pin industry. One needed to be certified and we all had to acid etch the pins we inspected.
A Keytos ring is a tool used to measure effectiveness of the equipment. The small through holes would show up as indications on the ring OD under blacklight.
 

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By the part # you posted I believe that is a 360 Magnum head, not an LA head. Am I correct? If so only heads from a magnum engine will work and nearly all of them you find will be cracked. It was an issue with them. EQ heads are an upgraded replacement head and not all that expensive.
 
That casting number is shown to be both 318 and 360 castings from 1977-1982. Available with the 1.78 (318 ) and 1.88 (360) valve sizes. Are you sure they are 360 heads? Because if they are the 1.78 318 heads, they are not even worth taking to the shop in the first place.
 
I don't think I've ever seen a 360 port size with a 1.78 valve. The 318 4bbls got the 360 top end with the 1.88 intake valves. I think the mentioning of a 1.78 intake valve might be a misprint because all other castings with the 318 port size had 1.78s.
 
RustyRatRod said:
That casting number is shown to be both 318 and 360 castings from 1977-1982. Available with the 1.78 (318 ) and 1.88 (360) valve sizes. Are you sure they are 360 heads? Because if they are the 1.78 318 heads, they are not even worth taking to the shop in the first place.
Click to expand...

crap. I think that you are right, did not measure it but it came off of a 360 motor from a used hot rod (1977 E-58 packaged 360 Volare Road Runner I bought) I remember reading something like that about the late 70's 318's and 360's sharing heads and maybe intakes when it came to four barrel packages like performance or police packages.

the machinist just told me that the intake valve measures 1.86

fishy68 said:
By the part # you posted I believe that is a 360 Magnum head, not an LA head. Am I correct? If so only heads from a magnum engine will work and nearly all of them you find will be cracked. It was an issue with them. EQ heads are an upgraded replacement head and not all that expensive.
Click to expand...

No sir, I took the rocker shafts off of the heads.

Well I guess I have a free 4071051 cylinder head if anybody wants one.

ragtopfury said:
Where is "Location: Itty Bitty Living Space." ? I've got a pair of heads from a mid 80's 360 I'll be selling off when I get into the shed again. Came off a 70k mile engine about 5 years ago and have been under a rag on a shelf in the shed ever since. If you are near Baltimore, make me an offer.
Click to expand...

I 'll hit you up after the Feb 15th's paycheck. I'm one step away from being 'broke as a joe' right now. I would be interested in greyhound shipping to Jacksonville, Florida later on.


thanks everyone!
 
Rodney probably has all the heads you can stand and he is fairly close. I would be glad to go pick you out a pair. Or even one if I can find a match.
 
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