I received the heads in question yesterday, tore them down and measured the guides. When they where brought in years ago they where almost new. They had .0015 clearance with about .0005 taper. They now have .0016-.0018 with .0015 taper on the worst guide and the rest have about .001. Yes, they are wore but they are not totally "wear out". I will note that the end exhaust ports are always the worst because of lack of water circulation in that part of the head. #2 #8 exhaust ports always wear more than the rest.

These are stock guides and at the time of rebuild many years ago I did not replace the guides because the guide issue was not a proven fact at that that time and the guides where great. These heads came from 21st century and they did a great job on them! I just freshened them up and sent them down the road. Now days when it come to guide wear on the ls7, we know better and we understand that the exhaust guides can have accelerated wear especially in conjunction with high lift cams. I now replace ALL guides on LS7 heads. I use the CHE high Nickle bronze which is more than sufficient for street use. All bronze guides are not the same!!!!!!! There are over 70 different formulations of bronze guide material! If you buy the cheapest Chinese Bronze ****, its going to wear FASTER than a stock guide! I can buy bronze guides for 1.02 each or pay for the ones that will hold up and pay 5.50 to as much as 8.00 each. If its cheap, its cheap for a reason! When someone complains about how fast there bronze guides wore out, ask them if they even know what type or manufacture they used because if you use CHE and give them adequate oil flow, you wont see that ****. I dont see my heads coming back with guide wear using CHE guides as should be the case!

On another note:
How many of you guys take a razor and slice the seal on the exhaust guides? If you do this they will get the oil they need but WILL NOT contaminate the cylinder. It will also cut your guide wear in HALF no matter what material you use. I also take off the springs at the top of the seal because its a joke to run that tight a seal on a "High Performance" engine. The ONLY reason the factory cut the oil flow to the guide down to a minimum is to pass EPA standards. If the guide is wearing thats a LACK OF LUBRICATION! Get some oil to it and it will stop. We NEVER run seals on high end race engines. The more friction you have, the more oil you need. It could not be any more simple.