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Old 10-16-2005, 03:42 AM   #21
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Quote:
Originally Posted by ssei1995
A bunch of stuff.
I really don't see how this is a bad idea.
Get a reground cam for cheaper.. find out how much material was ground off the base circle... mill the heads that much and effectively raise the compression.... maintain valvetrain geometry so you don't have to adjust anything...
Not everybody has $.
For some people, saving $100 or so is worth it.
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Old 10-16-2005, 05:49 AM   #22
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Quote:
I really don't see how this is a bad idea.
Get a reground cam for cheaper.. find out how much material was ground off the base circle... mill the heads that much and effectively raise the compression.... maintain valvetrain geometry so you don't have to adjust anything...
Well, first thing to check is to make sure the camshaft does not have a small base circle to start with. Many OEM hydraulic roller cams have already a small base circle. Making it small will weaken the camshaft, specially if you add stiffer springs combined with higher RPM'*.

Also, the smaller base circle drops the lifter deeper in the lifter bore If you drop the lifter too far down, the stock lifters can actually push themselves off the lifter guide. The result will be damage to the engine.
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Old 10-16-2005, 12:34 PM   #23
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Quote:
Originally Posted by ssei1995
You need to either buy or make an adjustable pushrod to get the proper length; you cannot guess by the amount you milled the heads. Also, you have to take into consideration the hydraulic lifter plunger travel too. You should have 0.020" to 0.060" preload on the lifter plunger; my preference is 0.030"/0.040" preload.
I'm a little confused by this statement, because we're not 'guessing' at anything. If we send the cam to CompCams and they regrind it, they should be able to tell us, "You need pushrods that are 'x' thousandths longer." Then we'll mill 'x' amount of material off the heads, which will restore all the parts to their original mathematical relationship. Is there something I'm missing? I don't want to do this improperly, but I'm having a hard time understanding your objections.

As far as lifter plunger travel is concerned, you know more about that than I do. I'm not an engine builder. But I don't see why we would have to take the lifters into consideration when we're simply reusing stock parts. They shouldn't give us any problems or act any differently than they do right now. Correct me if I'm wrong.

$100 for pushrods is the price that INTENSE and ZZP list on their websites. If they are available for less, I'll look into it. We're looking for cost cutting techniques that nobody has employed yet. We won't cut costs to the point of doing things 'wrong' or making the car vastly unreliable, because then we haven't really accomplished anything for the benefit of other L36 owners.
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Old 10-16-2005, 04:09 PM   #24
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I'm a little confused by this statement, because we're not 'guessing' at anything. If we send the cam to CompCams and they regrind it, they should be able to tell us, "You need pushrods that are 'x' thousandths longer." Then we'll mill 'x' amount of material off the heads, which will restore all the parts to their original mathematical relationship. Is there something I'm missing? I don't want to do this improperly, but I'm having a hard time understanding your objections.
Well, the tech guys at Comp Cams are not engine builders. When Comp Cams offers specific lengths for certain applications on their catalog, they are based on actual testing by other engine shops. I know this for a fact because in the past I did lots of business with many of the big cam manufacturers.

About the lifters, you need to take into consideration that travel since I assume you are chnaging the camshaft specifications which would include opening, closing, overlap, duration, lift , ramp profile and centerlines. In addition, you are milling the heads, however, I have not heard anything about the imapct of the head gasket thickness, which varies from manufacturer to manufacturer. When you are ready for pushrods, measure your required length and let me and I will tell you if there is an available OEM/off-the-shelf pushrod you can buy and use.
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Old 10-17-2005, 01:45 AM   #25
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I understand what you're saying, but it doesn't take an engine builder to tell us "We made the base circle of the cam 'x' inches smaller, so you'll need pushrods that are 'x' inches longer." That'* the number on which we'll base the calculations for our head work.

As far as the pushrods are concerned, we'll definitely talk to you or other people if we need new ones. However, we're hoping we don't even need to buy pushrods for this project. The goal is to use stock components in the effort to save cash. I guess we'll just have to see what happens after the cam is analyzed by Comp. Or maybe I should say if we have the cam analyzed by Comp .

Comments are still appreciated by anyone... I'm still interested to know the maximum amount of valve clearance we have when milling the heads. If nobody here knows, I'll check over at 3800Pro. Thanks!
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Old 10-17-2005, 01:07 PM   #26
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Hmmm, this is interesting. I just spoke to a CompCams representative over the phone and asked him a few questions about the regrinding process. I was surprised at a few of his answers.

First of all, they do not use a rehardening process after performing a regrind. He said that factory camshafts are "hardened pretty well" in the manufacturing process, and that additional rehardening after the regrind is unnecessary. Additionally he mentioned that if it'* a billet cam (is it?) it is quite hard throughout the material, and there would be nothing to worry about.

Secondly, I now understand what ssei1995 was saying about measuring pushrod length (though you could have explained it a little better in your posts). The technicians at Comp will not figure out a measurement for how much longer the pushrods need to be, so it'* up to Doug and I to get the proper length ourselves. The representative recommended measuring the base circle of the cam before and after the regrind in order to get an idea of how much material has been removed. I guess this process isn't as scientific as I believed it was.

Third, they have no warnings regarding the application of a reground cam. He said it could be used in a stock motor as well as a performance setup. I asked him if he could give any recommendations or additional advice that I should follow when dealing with a regrind, and he said there was none. The important thing is just to get the valvetrain components measured correctly.

So, what do you all think of this information? I don't know whether or not to believe him about the rehardening being unnecessary. Are our stock cams a billet material that is hardened all the way through? No hurry for an answer, but I'm glad I started asking these questions now instead of later when it'* time to do the project!
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Old 10-17-2005, 01:56 PM   #27
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The camshaft, during the regrinding process, will go through heat/thermal cycling, therefore, the ground surface hardness will not be there again. You will have a soft cam. Many knowledgeable engine builders that I know, do not use Comp Cams anymore since they have experienced cam failures due to soft cams. If I had to use a regrind, I will only go to Crane, Isky or Bullet cams.

I am glad your are smart enough to call and get clarification on the camshaft issue. I do not understand how they can say a reground is good for a high performance application?? It will be good only if you have a billet camshaft, still, it needs to be re-hardened after is reground. The increased valve spring pressure in a high performance or race application, in addition to having a non-hardened lobe is a recipe for disaster.
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Old 10-18-2005, 01:07 AM   #28
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Well, I guess I'll try some other vendors to see what they can offer. I've talked to a couple of mechanics that I know, and neither of them seem to have a problem with using a reground cam, especially since we're using stock valvetrain components. Let me remind you, this isn't a 'high performance' rebuild. We won't be running stronger valvesprings or higher RPMs than a stock application, so I'm thinking that a properly hardened regrind should be adequately reliable for our project.

Also, if anybody knows the valve clearance numbers I'm looking for, or the composition of the camshaft, I would greatly appreciate it!
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Old 10-18-2005, 01:51 AM   #29
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If you do not plan to race the car, or run high amounts of valve spring pressure; then I would recommend a private camshaft regrinder:
Give them a call. The have a quick turn around and very competitive pricing. They have lots of high performance lobes available that they can grind on your cam.
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Old 10-18-2005, 11:55 AM   #30
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Quote:
Originally Posted by ssei1995
If you do not plan to race the car
We will be running it at the drag strip, but it won't have higher spring pressures or get above 5800-6000 RPM. Does this change anything in your mind?
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