Majoraslayer
I'm Awesome
This may or may not be unpopular advice, but I want to throw in my two cents anyway to save someone else from the lessons I learned the hard way. You shouldn't worry about it right now, but IF you ever happen to blow a head gasket, budget for buying replacement aftermarket heads. I wouldn't go out of my way for it otherwise if things are running fine, but keep the advice in your pocket in case you ever do happen to take off your heads for some reason.
After buying a bunch of factory Vortec heads myself (8 in total at the end), and talking to the machine shop where I had them magnafluxed, the overwhelming majority of used factory GM 5.7 Vortec heads are cracked. I even bought an entire parts Vortec engine that ran fine before being pulled; I was going to swap it in to replace my TBI, but decided to just reuse the heads since my bottom end had less than half the mileage. The Vortec engine never ran hot, and came from a 1998 truck that was cared for meticulously. A trip to the machine shop later, and they found cracks in the coolant passages of the heads. Speaking from my own experience, I would treat all OEM 5.7 Vortec heads as disposable. I've talked to several people in person and online who have had the same experience I did. Any aftermarket Vortec head you buy, including the finest Chineseum, has an upgraded thicker casting that should mitigate the cracking problem that was so common in the original design. If your factory Vortecs aren't cracked yet, chances are high it's inevitable (if you're lucky, it will be somewhere that doesn't show symptoms for a very long time). If you're doing a project that has you removing the heads anyway, it's a great time to future-proof your engine against the problem by upgrading them.
I've seen several people get defensive about this claiming their heads are fine at such and such high mileage, but all evidence I've seen has convinced me that replacing those heads if you ever happen to have them off would be worth it for longevity.
After buying a bunch of factory Vortec heads myself (8 in total at the end), and talking to the machine shop where I had them magnafluxed, the overwhelming majority of used factory GM 5.7 Vortec heads are cracked. I even bought an entire parts Vortec engine that ran fine before being pulled; I was going to swap it in to replace my TBI, but decided to just reuse the heads since my bottom end had less than half the mileage. The Vortec engine never ran hot, and came from a 1998 truck that was cared for meticulously. A trip to the machine shop later, and they found cracks in the coolant passages of the heads. Speaking from my own experience, I would treat all OEM 5.7 Vortec heads as disposable. I've talked to several people in person and online who have had the same experience I did. Any aftermarket Vortec head you buy, including the finest Chineseum, has an upgraded thicker casting that should mitigate the cracking problem that was so common in the original design. If your factory Vortecs aren't cracked yet, chances are high it's inevitable (if you're lucky, it will be somewhere that doesn't show symptoms for a very long time). If you're doing a project that has you removing the heads anyway, it's a great time to future-proof your engine against the problem by upgrading them.
I've seen several people get defensive about this claiming their heads are fine at such and such high mileage, but all evidence I've seen has convinced me that replacing those heads if you ever happen to have them off would be worth it for longevity.
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