How Much Valve Guide Wear Is Acceptable?
How Much Valve Guide Wear Is Acceptable? I sent a set of 706 heads out to get them opened up for 2" intake valves. What is bothering me is that after I got them back as I'm disassembling them to install PAC 1218 springs I'm finding some of the valve guides are worn. By that I mean I can lift the valve off the seat just enough to grab the perimeter of the valve and then I can rock it back and forth which is showing me there is valve guide wear. It's obvious from looking at the heads that the guides were not replaced. 3 of the 4 cylinders on this one head have exhaust valve guide wear. 2 of the intakes are showing notable side to side movement when I do the same "wiggle" test. The other head every valve is rock solid with no side to side wiggle. What would you guys do? Should I take them back and show them what I'm seeing? How can a valve job be done with a worn guide in place? I thought the seat cutters piloted off of the valve guide bore... If anyone has any experience, or suggestions, with this I would appreciate it. Maybe I'm worrying about nothing. It just occurs to me that on this one head there are a few guides that are rock solid with no wiggle, but the rest have measurable side to side play.
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What exactly was requested of the machine shop to do? If it was strictly to put in the larger valves, guides might be an extra chore, THOUGH they should have advised you on the worn guides, as I have a feeling that would affect concentricity of the new seats.
I paid for 2" valves, and a VALVE job which included a 5 angle cut, new intake valves, and new valve guide seals. I can't imagine that the valve guide seals are gonna last with the valve stems moving around that much. Plus, if the valve is not closing concentrically to the cut angles on the seats, is that not going to beat up the cut angles? They did not tell me that the guides were worn, and I did not specifically ask for them to be replaced. I would have assumed they would have checked them, and then up-sold me if they were needed...
What would you guys do? I've heard of some type of reamer you can run through there that will displace the metal allowing the valve to be held properly.
I don't want to create drama for the shop.
Maybe I'll just buy some new guides and press them in myself, and then lap the valves to see if they are still seating properly, and sealing.
What would you guys do? I've heard of some type of reamer you can run through there that will displace the metal allowing the valve to be held properly.
I don't want to create drama for the shop.
Maybe I'll just buy some new guides and press them in myself, and then lap the valves to see if they are still seating properly, and sealing.
Here's a good video on the subject of valve guide clearance.
https://www.google.com/search?rlz=1C...rqtsPsoC22As15
https://www.google.com/search?rlz=1C...rqtsPsoC22As15
It's significantly more then .001-.003. They almost move enough from side to side that you can hear an audible click when they stop in the direction you are moving them. How they missed it... I'm not sure.
I wonder what it would cost just to do them all on that head. Ima call the machine shop and see what they say. If several are worn, it might mean that the rest are right on the verge of being worn out as well. Would make more sense to just do them all on that one head.
I wonder what it would cost just to do them all on that head. Ima call the machine shop and see what they say. If several are worn, it might mean that the rest are right on the verge of being worn out as well. Would make more sense to just do them all on that one head.
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I paid for 2" valves, and a VALVE job which included a 5 angle cut, new intake valves, and new valve guide seals. I can't imagine that the valve guide seals are gonna last with the valve stems moving around that much. Plus, if the valve is not closing concentrically to the cut angles on the seats, is that not going to beat up the cut angles? They did not tell me that the guides were worn, and I did not specifically ask for them to be replaced. I would have assumed they would have checked them, and then up-sold me if they were needed...
What would you guys do? I've heard of some type of reamer you can run through there that will displace the metal allowing the valve to be held properly.
I don't want to create drama for the shop.
Maybe I'll just buy some new guides and press them in myself, and then lap the valves to see if they are still seating properly, and sealing.
What would you guys do? I've heard of some type of reamer you can run through there that will displace the metal allowing the valve to be held properly.
I don't want to create drama for the shop.
Maybe I'll just buy some new guides and press them in myself, and then lap the valves to see if they are still seating properly, and sealing.
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Verdad Gallardo I'm almost 100% certain the valves are AFTER-MARKET (CHINESIUM) valves. I went and talked to them about needing some valve guides. They said they only had 4 left in in stock for the LS heads. They handed me the 4 and did not charge me. After inspecting the new guides they gave me-which do appear to be new-they are of the KNURLED design. Looking down into the new guide, it looks like it is threaded internally. The original GM guides are SMOOTH inside providing significantly more surface area than the after-market knurled guides. I already drove the old guides that were worn out of the head. I now need SMOOTH guides to drive in, then I will turn it back over for a valve job after that.
I did not get an itemized list for the work. I simply handed them the heads and said I wanted them updated to 2" intake valves, and a 5 angle valve job. I got the heads back with new guide seals, new 2" intake valves, and all 16 valves and seats cut. Once I got them back to the shop I wanted to upgrade the springs to PAC 1218's, and pocket port them at the same time. As I was removing the valves I was "wiggle" testing them and found the issue.
Anyways.. I'm now looking for replacement valve guides if anyone knows where to find them. They must be SMOOTH inside.. not knurled. Okay, I did a Google search and they come right up.. I've heard that the IRON guides are the best.. But all I'm seeing are Bronze, or Manganese.. Does it really matter? Low lift cam (.551"), stock rockers.
I did not get an itemized list for the work. I simply handed them the heads and said I wanted them updated to 2" intake valves, and a 5 angle valve job. I got the heads back with new guide seals, new 2" intake valves, and all 16 valves and seats cut. Once I got them back to the shop I wanted to upgrade the springs to PAC 1218's, and pocket port them at the same time. As I was removing the valves I was "wiggle" testing them and found the issue.
Anyways.. I'm now looking for replacement valve guides if anyone knows where to find them. They must be SMOOTH inside.. not knurled. Okay, I did a Google search and they come right up.. I've heard that the IRON guides are the best.. But all I'm seeing are Bronze, or Manganese.. Does it really matter? Low lift cam (.551"), stock rockers.
Last edited by Kawabuggy; May 13, 2022 at 04:04 PM.
It's significantly more then .001-.003. They almost move enough from side to side that you can hear an audible click when they stop in the direction you are moving them. How they missed it... I'm not sure.
I wonder what it would cost just to do them all on that head. Ima call the machine shop and see what they say. If several are worn, it might mean that the rest are right on the verge of being worn out as well. Would make more sense to just do them all on that one head.
I wonder what it would cost just to do them all on that head. Ima call the machine shop and see what they say. If several are worn, it might mean that the rest are right on the verge of being worn out as well. Would make more sense to just do them all on that one head.
Did you check your guides for wear with your old original valves in the head before you took them to the machine shop? If you didn't pull one of your new aftermarket valves out of the head and measure the valve stem diameter . Then measure the diameter on a new GM valve stem diameter I have found some aftermarket valves to be on the skinny side. So let's say that the GM valve measures 313 and the aftermarket valve measures point 312 you have one thousand difference . If you're where at .003 with the old GM valve now you've got a sloppy 004
Its more the exhaust guides that are sloppy. The exhaust valves are factory GM, not new. The only new valves are the new, larger, 2" valves. I had a great idea today. I've got 3 317 heads here at the shop that I will never, ever, use. I think I'm gonna cannibalize one of these 317 heads IF the guides in that head are any good. I realize I will still have to send the head out for a valve job after all this. Going this route would certainly speed up my time line as I could have this head finished early next week, and this motor off my stand so I can start on the next one.
It works! I have an old 317 head here that has an epoxied on tag indicating it was "REBUILT" on the end of it.. I drove out 2 of the guides and put them into my subject head, and now there is no perceptible movement side to side at the valve head when it is just off the seat between .200"-.400". I've already ordered a complete set of Manganese guides and will keep them for the next head I'm working on. Next set of heads I do I will perform the wiggle test BEFORE I send them out for work, and replace the guides myself if they need it.
I think I'm starting to see a pattern here.. I tore the old 4.8L engine down myself and can tell you that it was ALL GM parts inside. That motor DID have multiple failed rocker arms-grunged up on the face where it contacts the valve stem, and also damage in the cup area where the push rod rides, and as a result several of the push rods from that motor were also PAC-MANNED out.. Those of you who have seen that type of damage will know what PAC-MANNED means.. That's pretty much par for the course on every LS engine I tear down though. I always find roached rockers with wear at the cup and also on the face where it slides across the valve stem.. I guess going forward I will be extra vigilant on those engines that I tear down that have roached rockers as I now believe that may be what is imparting a side load on the valve and causing the guide wear that I am seeing. I'll put this down to experience and allow it to benefit me, and my builds, going forward.
I think I'm starting to see a pattern here.. I tore the old 4.8L engine down myself and can tell you that it was ALL GM parts inside. That motor DID have multiple failed rocker arms-grunged up on the face where it contacts the valve stem, and also damage in the cup area where the push rod rides, and as a result several of the push rods from that motor were also PAC-MANNED out.. Those of you who have seen that type of damage will know what PAC-MANNED means.. That's pretty much par for the course on every LS engine I tear down though. I always find roached rockers with wear at the cup and also on the face where it slides across the valve stem.. I guess going forward I will be extra vigilant on those engines that I tear down that have roached rockers as I now believe that may be what is imparting a side load on the valve and causing the guide wear that I am seeing. I'll put this down to experience and allow it to benefit me, and my builds, going forward.
Anybody in need of a 317 casting? No valves, springs, retainers, or guide seals, and is missing 5 valve guides... But it's free if anyone needs it. If no one wants it, its going in the trash barrel. NOT cracked, not damaged in any way that I can visibly see.. Just cannibalized for parts by me. I do have a COMPLETE set of 317 heads ready to bolt on. They are THAT clean.. and I'll never use them. I also have a complete set of 243's if anyone is looking. I have not put them up in the market place yet, though that would probably get them out of my shop the quickest.
I got all 5 "loose" guides changed out on the 706 head, and it's boxed up going to the machine shop on Monday-yes, a different shop this time-to get the valve job done.
I got all 5 "loose" guides changed out on the 706 head, and it's boxed up going to the machine shop on Monday-yes, a different shop this time-to get the valve job done.
Anybody in need of a 317 casting? No valves, springs, retainers, or guide seals, and is missing 5 valve guides... But it's free if anyone needs it. If no one wants it, its going in the trash barrel. NOT cracked, not damaged in any way that I can visibly see.. Just cannibalized for parts by me. I do have a COMPLETE set of 317 heads ready to bolt on. They are THAT clean.. and I'll never use them. I also have a complete set of 243's if anyone is looking. I have not put them up in the market place yet, though that would probably get them out of my shop the quickest.
I got all 5 "loose" guides changed out on the 706 head, and it's boxed up going to the machine shop on Monday-yes, a different shop this time-to get the valve job done.
I got all 5 "loose" guides changed out on the 706 head, and it's boxed up going to the machine shop on Monday-yes, a different shop this time-to get the valve job done.