| Re: Engine swap on the C1 |
Subject: Re: Engine swap on the C1 by BeachBum on 2008/11/24 20:51:12 You know I understand your pain.... I really do. And things like what happened to yours happen all the time, not just with AFR cylinder heads, but every type of cylinder head. Hence, why many of those cylinder head porters have acquired impressive welding skills as well. In fact, many times the customer never knows about it, they drop off the cylinder heads and then pick them up a week or two later..... the problem with yours, apparently 1 or 2 of the holes were too deep to be repaired. If they weren't, you probably would have never known they even broke through to begin with..... they would have repaired and cleaned them up and given them back. That is bad luck ! But, I will say, your cylinder head porter should have caught the problem way before they made a cut .. what is the old adage ?.... measure twice, cut once. They really needed to touch off or probe a few known positions on that cylinder head before plunging a cutter into it. In addition, if your cylinder heads had serious core shift, they should have known 2 seconds after that cutter hit the material that something was wrong and stopped the CNC program. Most qualified CNC machinist, when first starting a program will have one hand on the feedrate override and other hand on e-stop, thus when that cutter hits the material if there is the slightest of problem such as not cutting anything but air, or a much too heavy cut .. an experienced cnc machinist will know this literally a second into the cutter path and will stop the CNC program dead in its track. They can even typically analyze the chip itself and make adjustments on the spindle speed and/or axes feedrate to create a better cut/chip. In addition, at the very, very least after doing the first port, they needed to do a program stop and then inspect the material with the very least a dial indicator as well as inspect the cutter itself. If everything was A-okay, then let the program stepover and repeat, stop again and test . To be honest, even if your cylinder heads looked like a crooked building, the machining never should have gotten past the 1st port. You just dont slap on somebodys expensive cylinder heads, press cycle start and go get a cup of coffee unless you are careless. But, at the end of the day, the reality of it is, a cylinder head manufacturer is selling you a cylinder head that is based upon the chamber size they advertised, flow numbers & runner size..... and of course they need to be able to bolt-up and seal. After that, no cylinder head manufacturer can guarantee a cylinder head porters program will work with the given cylinder head..... they have no idea where and how the G-code tool path was created in the first place, it would be impossible for them to guarantee everybodys porting program won't break through. Not to mention the skill level of the CNC machinist. Its hard for me to explain this, but it is reality.... But, my personal conclusion is that if your cylinder heads are so severely shifted that the heads wont seal or even match-up to the intake or the chamber size or runner size are beyond advertised or they do not flow what is advertised, then that would be AFRs fault !! But, if somebody cuts a bunch of holes in these cylinder heads, regardless of anything else, that is the fault of the person doing the cutting . Good Luck ! |
