regrind cam
03-14-2009, 10:31 AM
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regrind cam I was looking on ebay and they had some comp regrinds selling for cheap. I don't know what they mean by regrind. I thought about buying one but I don't want to stick in my motor and have a lobe round off or anything. Please let me know thanks!
03-14-2009, 11:20 AM
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03-14-2009, 11:22 AM
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as long as the grind was done well all you would have to do is get some new pushrods and try it out.
a regrind chnages the base circle in order to get the profile so the lifter rides further down in the bore to maintian the same cam profile.
a regrind chnages the base circle in order to get the profile so the lifter rides further down in the bore to maintian the same cam profile.
03-23-2010, 04:07 PM
#7
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I have purchased three of the cams, and installed two of them. The first one was an LS6 copy that doesnt run at all like a stock LS6 cam. The idle is choppy.
The next cam was an LS6 copy purchased from the same guy in Texas. This cam was ground so bad that the engine wouldnt idle on two cylinders. It was removed (after a lot of troubleshooting because heads and intake were done at the same time) and replaced with a factory GM LS6 cam. The factory cam Idles and works great. I am re4placing the other copy in the other car with a GM cam.
I contacted the Ebay guy from Texas, that I purchased them from two times, and he never got back to me. I would never use a reground cam again, it is not worth the headache.
I have purchased three of the cams, and installed two of them. The first one was an LS6 copy that doesnt run at all like a stock LS6 cam. The idle is choppy.
The next cam was an LS6 copy purchased from the same guy in Texas. This cam was ground so bad that the engine wouldnt idle on two cylinders. It was removed (after a lot of troubleshooting because heads and intake were done at the same time) and replaced with a factory GM LS6 cam. The factory cam Idles and works great. I am re4placing the other copy in the other car with a GM cam.
I contacted the Ebay guy from Texas, that I purchased them from two times, and he never got back to me. I would never use a reground cam again, it is not worth the headache.
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03-23-2010, 06:21 PM
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Reground cam / lifter position OK, I am not highly experienced in the engine design world, but I will share my thoughts and see if I am out to lunch or not.
1) Regrind cam is where an existing cam is taken and ground down to create a different profile.
Logically, there are limitations to what shape you can create.
You can only change lobe center line so much as an example.
2) I believe most cams have a hardened surface to help them be more durable. When re grinding, you are removing some of the hardened surface and potentially past the limit of the hardened surface into the softer base material. If you get to this point, it would have to be a bad thing.
3) With the smaller base circle (the result of grinding the cam smaller) this would logically result in the lifter sitting lower. This was mentioned by someone earlier in this thread.
It makes sense that you would require longer push rods to make up for the missing material or at the very least the rocker would have to be adjusted down further. Affecting rocker orientation to the valve tip.
Also, doesn't the lifter get filled by oil when it is at rest and then as it lifts, the port or hole that it is filled with closes some how to keep the oil in and this gives the solid surface that pushes against the push rod.
If you drop the lifter lower in it's pocket, wouldn't the closing point of this oil port change?
Just thinking about this because a machinist friend of mine mentioned that he knows a guy who just traced a ***** Thumper cam for an LS1 and if I wanted, I could take a stock cam and have this guy grind the ***** profile on it.
1 of the restrictions was that the guy will only grind away so much material because he doesn't like grinding past the hardened surface.
I trust my buddy, he's been building engines for years and is a very compotent machinist. If he thinks the regrind will work, it should.
However, after hearing about the bad experiences here, I will have to think on this some more.
1) Regrind cam is where an existing cam is taken and ground down to create a different profile.
Logically, there are limitations to what shape you can create.
You can only change lobe center line so much as an example.
2) I believe most cams have a hardened surface to help them be more durable. When re grinding, you are removing some of the hardened surface and potentially past the limit of the hardened surface into the softer base material. If you get to this point, it would have to be a bad thing.
3) With the smaller base circle (the result of grinding the cam smaller) this would logically result in the lifter sitting lower. This was mentioned by someone earlier in this thread.
It makes sense that you would require longer push rods to make up for the missing material or at the very least the rocker would have to be adjusted down further. Affecting rocker orientation to the valve tip.
Also, doesn't the lifter get filled by oil when it is at rest and then as it lifts, the port or hole that it is filled with closes some how to keep the oil in and this gives the solid surface that pushes against the push rod.
If you drop the lifter lower in it's pocket, wouldn't the closing point of this oil port change?
Just thinking about this because a machinist friend of mine mentioned that he knows a guy who just traced a ***** Thumper cam for an LS1 and if I wanted, I could take a stock cam and have this guy grind the ***** profile on it.
1 of the restrictions was that the guy will only grind away so much material because he doesn't like grinding past the hardened surface.
I trust my buddy, he's been building engines for years and is a very compotent machinist. If he thinks the regrind will work, it should.
However, after hearing about the bad experiences here, I will have to think on this some more.
03-23-2010, 11:48 PM
#11
Seriously I hope am not out of line but you get what you pay for. The cam is the heart of your engine. I know you will end up doing what you want but if there is one thing DO NOT skimp on a cam/valve train. You will be one of those guys screaming how your valve train failed and the cam was the issue and so on and so on.
03-24-2010, 11:38 AM
#12
I bought one of those cams from that guy. Ran it less than a year and when I pulled it out ALL of the lobes large ruts in them where the roller touches them!
DO NOT BUY THESE CAMS!!!
DO NOT BUY THESE CAMS!!!
