How I hardened my GM guide plates.
10-17-2006, 09:13 PM
#1
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How I hardened my GM guide plates.
A while back my GM guide plates all showed what I thought was excess wear. They all had around .030" -.050" of missing metal in the slots where the push rods slide and one wore an outrageous .125 which allowed the roller rocker to fall off the valve. The rocker was destroyed and the valve stem face was damaged.
Of course all this missing metal ended up in my engine. The GM guide plates are NOT hardened and are susceptible to wear when using hardened push rods. A file being drawn across the guide plate would easily cut right into it and remove a thin layer of metal. This makes no sense to me at all, I think that any wear at all is too much so I decided to try to harden my new set of GM guide plates so that this would not happen again.
I had the newly case hardened guide plates evaluated by a very experienced machinist and two mechanical engineers at work and they all agreed that the plates were now very much more resistant to wear. Here is how I did it.
You need Kasenit no.2 which sells for $135.00 for 10 pound can.
http://www1.mscdirect.com/CGI/NNSRIT...MT4NO=13059242
The Kasenit is gray powder that smells like cat ****, it has organic substances including bone in it that adds more carbon to low carbon metal like the GM guide plates. You can reuse the powder over an over. I was allowed to borrow the can from a machine shop so it did not cost me any money out of pocket.
What I did was heat the slots in each guide plate to cherry red with oxy-acetylene torch, then dip the glowing guide plate in the Kasenit powder for about a minute to cool. Then pull it out of the powder and clean off excess crusty powder. Repeat this process three times.
Once you have heated, dipped and cleaned three times heat it up one last time and dunk in clean water till it is completely cooled. The guide plate is now case hardened, it just needs to be cleaned and installed.
Before doing this a metal cutting file would easily cut into the guide plate, after the process the same file wont even leave a blemish. It even sounds entirely different when doing the file test.
Doing the process was very well worth it and like I said there is not even the slightest bit of wear or blemish on my guide plates, I checked them again tonigh after 5K miles so. It took about an hour and a half plus a lot of acetylene and oxygen to do it.
I think there is some money to be made here and shame on GM for not hardening the guide plates in the first place. Just thought I would share this with everyone.
Of course all this missing metal ended up in my engine. The GM guide plates are NOT hardened and are susceptible to wear when using hardened push rods. A file being drawn across the guide plate would easily cut right into it and remove a thin layer of metal. This makes no sense to me at all, I think that any wear at all is too much so I decided to try to harden my new set of GM guide plates so that this would not happen again.
I had the newly case hardened guide plates evaluated by a very experienced machinist and two mechanical engineers at work and they all agreed that the plates were now very much more resistant to wear. Here is how I did it.
You need Kasenit no.2 which sells for $135.00 for 10 pound can.
http://www1.mscdirect.com/CGI/NNSRIT...MT4NO=13059242
The Kasenit is gray powder that smells like cat ****, it has organic substances including bone in it that adds more carbon to low carbon metal like the GM guide plates. You can reuse the powder over an over. I was allowed to borrow the can from a machine shop so it did not cost me any money out of pocket.
What I did was heat the slots in each guide plate to cherry red with oxy-acetylene torch, then dip the glowing guide plate in the Kasenit powder for about a minute to cool. Then pull it out of the powder and clean off excess crusty powder. Repeat this process three times.
Once you have heated, dipped and cleaned three times heat it up one last time and dunk in clean water till it is completely cooled. The guide plate is now case hardened, it just needs to be cleaned and installed.
Before doing this a metal cutting file would easily cut into the guide plate, after the process the same file wont even leave a blemish. It even sounds entirely different when doing the file test.
Doing the process was very well worth it and like I said there is not even the slightest bit of wear or blemish on my guide plates, I checked them again tonigh after 5K miles so. It took about an hour and a half plus a lot of acetylene and oxygen to do it.
I think there is some money to be made here and shame on GM for not hardening the guide plates in the first place. Just thought I would share this with everyone.
Last edited by wrd1972; 12-11-2007 at 08:51 PM.
10-17-2006, 10:20 PM
#3
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Location: Little Rock, AR
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Re: How I hardened my GM guide plates.
IIRC, your problem was due to something else that was causing excessive side thrust and wearing the plates. Properly setup valvetrains don't have this problem or everyone would have worn out guideplates. I don't see that there is "money to be made" in hardening something that should not have to be hardened any more than it is in the first place.
20k miles on my unhardened GM plates don't show anything unusual.
That's because I don't believe there is one. Your test results would be interesting, though. 
20k miles on my unhardened GM plates don't show anything unusual.
Last edited by shoebox; 10-17-2006 at 10:22 PM.
10-18-2006, 09:56 AM
#6
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Location: Iowa
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Re: How I hardened my GM guide plates.
That is not necessarily true. That method can be used to harden metals with a specific composition and carbon content. Doing this to a low carbon steel won't do anything but discolor it. With the correct metal it will be very hard, too hard for the application I think as the part will be hardened all the way through. A cace hardening is only .005-.030 deep depening on the methods and metals used.
10-18-2006, 11:50 AM
#7
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Location: Kantuckee Yo'
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Re: How I hardened my GM guide plates.
IIRC, Properly setup valvetrains don't have this problem or everyone would have worn out guideplates. I don't see that there is "money to be made" in hardening something that should not have to be hardened any more than it is in the first place.
20k miles on my unhardened GM plates don't show anything unusual.
20k miles on my unhardened GM plates don't show anything unusual.
It makes sense to me that if you have a hardened metal part is constantly rubbing against a NON hardened metal part then that part will be more prone to wear. Obviously both parts should be similar in hardness.
Isky does harden their guide plates as well as Comp I think, might be wrong there. Assuming all things are setup right, their are clearly benefits and piece of mind of knowing that a potential weak link has been greatly beefed up. There is no doubt in my mind that my GM plates are much better, there is not even a hairs blemish in the push rod slots after 5K miles.
Plus I am still running on that damaged valve with the rounded stem tip which you would think would cause the same guide plate wear problem, no blemish in that slot period. I will be installing LE2 heads in the next month or two.
Last edited by wrd1972; 10-18-2006 at 11:56 AM.
10-18-2006, 01:44 PM
#8
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Join Date: Oct 2002
Location: Upstate NY
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Re: How I hardened my GM guide plates.
A while back my GM guide plates all showed what I thought was excess wear. They all had around .030" -.050" of missing metal in the slots where the push rods slide and one wore an outrageous .125 which allowed the roller rocker to fall off the valve. The rocker was destroyed and the valve stem face was damaged.
Of course all this missing metal ended up in my engine. The GM guide plates are NOT hardened and are susceptible to wear when using hardened push rods. A file being drawn across the guide plate would easily cut right into it and remove a thin layer of metal. This makes no sense to me at all, I think that any wear at all is too much so I decided to try to harden my new set of GM guide plates so that this would not happen again.
I had the newly case hardened guide plates evaluated by a very experienced machinist and two mechanical engineers at work and they all agreed that the plates were now very much more resistant to wear. Here is how I did it.
You need Kasenit no.2 which sells for $135.00 for 10 pound can.
http://www1.mscdirect.com/CGI/NNSRIT...MT4NO=13059242
Don't waste your money on the cheaper no.1 product cause it will not work. The Kasenit is gray powder that smells like cat ****, it has organic substances including bone in it that adds more carbon to low carbon metal like the GM guide plates. You can reuse the powder over an over. I was allowed to borrow the can from a machine shop so it did not cost me any money out of pocket.
What I did was heat the slots in each guide plate to cherry red with oxy-acetylene torch, then dip the glowing guide plate in the Kasenit powder for about a minute to cool. Then pull it out of the powder and clean off excess crusty powder. Repeat this process three times.
Once you have heated, dipped and cleaned three times heat it up one last time and dunk in clean water till it is completely cooled. The guide plate is now case hardened, it just needs to be cleaned and installed.
Before doing this a metal cutting file would easily cut into the guide plate, after the process the same file wont even leave a blemish. It even sounds entirely different when doing the file test.
Doing the process was very well worth it and like I said there is not even the slightest bit of wear or blemish on my guide plates, I checked them again tonigh after 5K miles so. It took about an hour and a half plus a lot of acetylene and oxygen to do it.
I think there is some money to be made here and shame on GM for not hardening the guide plates in the first place. Just thought I would share this with everyone.
Of course all this missing metal ended up in my engine. The GM guide plates are NOT hardened and are susceptible to wear when using hardened push rods. A file being drawn across the guide plate would easily cut right into it and remove a thin layer of metal. This makes no sense to me at all, I think that any wear at all is too much so I decided to try to harden my new set of GM guide plates so that this would not happen again.
I had the newly case hardened guide plates evaluated by a very experienced machinist and two mechanical engineers at work and they all agreed that the plates were now very much more resistant to wear. Here is how I did it.
You need Kasenit no.2 which sells for $135.00 for 10 pound can.
http://www1.mscdirect.com/CGI/NNSRIT...MT4NO=13059242
Don't waste your money on the cheaper no.1 product cause it will not work. The Kasenit is gray powder that smells like cat ****, it has organic substances including bone in it that adds more carbon to low carbon metal like the GM guide plates. You can reuse the powder over an over. I was allowed to borrow the can from a machine shop so it did not cost me any money out of pocket.
What I did was heat the slots in each guide plate to cherry red with oxy-acetylene torch, then dip the glowing guide plate in the Kasenit powder for about a minute to cool. Then pull it out of the powder and clean off excess crusty powder. Repeat this process three times.
Once you have heated, dipped and cleaned three times heat it up one last time and dunk in clean water till it is completely cooled. The guide plate is now case hardened, it just needs to be cleaned and installed.
Before doing this a metal cutting file would easily cut into the guide plate, after the process the same file wont even leave a blemish. It even sounds entirely different when doing the file test.
Doing the process was very well worth it and like I said there is not even the slightest bit of wear or blemish on my guide plates, I checked them again tonigh after 5K miles so. It took about an hour and a half plus a lot of acetylene and oxygen to do it.
I think there is some money to be made here and shame on GM for not hardening the guide plates in the first place. Just thought I would share this with everyone.
I agree that buying hardened plates that fit or using adjustable plates is a TON easier.
10-18-2006, 03:32 PM
#10
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Join Date: Oct 2001
Location: newton, kansas, USA
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Re: How I hardened my GM guide plates.
My pushrods rubbed the GM guide plates right at the very bottom of the guide plate not on the sides. I just took them off and ground them deeper so the push rod wouldn't rub it anymore. Is this where yours is rubbing?
10-18-2006, 06:57 PM
#13
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Re: How I hardened my GM guide plates.
10-18-2006, 08:16 PM
#14
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Re: How I hardened my GM guide plates.
Results are in...the GMPP guideplates are JUNK!!!
For a base I rockwell'd a CompCams guideplate and it came in at 32 rockwell C, which is exactly where it should be - you should look for 30-35 RC for a guideplate.
The GMPP guideplate did not even register on the C scale
, to find out where it is I would have had to tear the machine apart and re-calibrate it for the lower scale...the guideplate is NOT hardened and it is mild steel that will not harden by heat treating it. The only way to harden those is by the method that started this thread, which is actually only a surface hardening by inducing concentrated carbon into the surface of the metal.
Use Isky adjustables...don't risk using these GMPP plates.
For a base I rockwell'd a CompCams guideplate and it came in at 32 rockwell C, which is exactly where it should be - you should look for 30-35 RC for a guideplate.
The GMPP guideplate did not even register on the C scale
, to find out where it is I would have had to tear the machine apart and re-calibrate it for the lower scale...the guideplate is NOT hardened and it is mild steel that will not harden by heat treating it. The only way to harden those is by the method that started this thread, which is actually only a surface hardening by inducing concentrated carbon into the surface of the metal.Use Isky adjustables...don't risk using these GMPP plates.
10-18-2006, 08:35 PM
#15
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Re: How I hardened my GM guide plates.
This information is not surprising to me at all.
Machinistone:
Do you think it is possible for some peoples guide plates to wear down from hardened push rods even if the geometry and setup are good especially under hard use and high RPM's.
The Isky's are now sounding better than ever.
I will send you one of my hardened GM's plates for you to test.
Machinistone:
Do you think it is possible for some peoples guide plates to wear down from hardened push rods even if the geometry and setup are good especially under hard use and high RPM's.
The Isky's are now sounding better than ever.
I will send you one of my hardened GM's plates for you to test.