Cracked Valve Guide Pillars - OK to Use?
I have the heads off on my 1965 383 and noticed a possible problem from peering thru the valve springs. On one head, all of the exhaust valve guide pillars (correct name?) are missing chunks or at least cracked. I wasn't planning a valve job and just had the heads off to mill a smooth surface to better seat the valve covers and stop oil leaks which drove me nuts for years (done). 1st photo shows the worst one, where I removed the spring. It seems the valve guide sits in enough meat to secure it well, and it protrudes past the cast-iron pillar (keeps oil away). The second photo is the same PN head (2406516, "L", closed-chamber) I found for sale on ebay, which has even worse pillars , several cracked off completely. I can't tell about my intake valves since the shop used seals which have a wire spring to secure them to the pillar (instead of umbrella seals).
Is this head OK to use as is? Does anyone know the purpose of these pillars, and if they exist on later PN heads? Is the purpose to help keep oil from pooling against the valve guide? To provide structural support to the guide? Hard to imagine since fairly thin brittle cast-iron. Could the pillars have broken when the shop installed new valve guides and just didn't tell me? I haven't pulled the oil pan yet to look for debris, though that could be inconclusive since it could have come out with the oil. I didn't find any debris in the valley, so wonder if the heads were like this when I installed them in 2001. The shop which did the head job was a high-volume place in south Atlanta. The mechanic exclaimed, "lucky you have the desirable L heads", so seemed like he appreciated working on them. I'm now in CA. Haven't driven the car but ~5000 miles since then. Haven't noticed any blue smoke or oil loss. I mainly worry if the valve guides could get loose or more cast-iron cracks off to put debris in the engine. Any comments appreciated. I am sure some will say "toss the heads", because no cost for them. I have considered aluminum heads, but that can cause new issues (valve-train geometry, risks of warpage, high cost).
I have the heads off on my 1965 383 and noticed a possible problem from peering thru the valve springs. On one head, all of the exhaust valve guide pillars (correct name?) are missing chunks or at least cracked. I wasn't planning a valve job and just had the heads off to mill a smooth surface to better seat the valve covers and stop oil leaks which drove me nuts for years (done). 1st photo shows the worst one, where I removed the spring. It seems the valve guide sits in enough meat to secure it well, and it protrudes past the cast-iron pillar (keeps oil away). The second photo is the same PN head (2406516, "L", closed-chamber) I found for sale on ebay, which has even worse pillars , several cracked off completely. I can't tell about my intake valves since the shop used seals which have a wire spring to secure them to the pillar (instead of umbrella seals).
Is this head OK to use as is? Does anyone know the purpose of these pillars, and if they exist on later PN heads? Is the purpose to help keep oil from pooling against the valve guide? To provide structural support to the guide? Hard to imagine since fairly thin brittle cast-iron. Could the pillars have broken when the shop installed new valve guides and just didn't tell me? I haven't pulled the oil pan yet to look for debris, though that could be inconclusive since it could have come out with the oil. I didn't find any debris in the valley, so wonder if the heads were like this when I installed them in 2001. The shop which did the head job was a high-volume place in south Atlanta. The mechanic exclaimed, "lucky you have the desirable L heads", so seemed like he appreciated working on them. I'm now in CA. Haven't driven the car but ~5000 miles since then. Haven't noticed any blue smoke or oil loss. I mainly worry if the valve guides could get loose or more cast-iron cracks off to put debris in the engine. Any comments appreciated. I am sure some will say "toss the heads", because no cost for them. I have considered aluminum heads, but that can cause new issues (valve-train geometry, risks of warpage, high cost).
