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Original Message
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| It depends....... |
| By kevin - 01/20/2003 12:38:47 PM; IP 209.240.198.61 |
| on who did the valve job, and installed the intake. If you leave off the rocker shafts, and make a plate with a fitting, you can put a Mityvac on there and test the intake valve/seat, as well as the manifold seal. You would have to plate each exhaust port individually to test, but the shafts can be on, just turn the motor over. I used to do the chambers with a plate after doing the valve job. After a while, I would use my mouth (I acid cleaned all my parts) on the ports, and suck till I was blue in the face (not really). I could tell if there was any leaks (never in my work, but I found it in others). If a suspect leak was found, I used the vac. I got real good results and extremly long life by doing the following. After all the other work to guides etc was done, I ground the seats to a 45 degree angle. Doing this right takes some time, as it is easy to do a "quickie". I used a Serdi cutter, then followed up with traditional stones (very fine finishing grade) on the sealing surface, redressing the stones a lot to keep them perfect. Then I would grind the valve face to 44-3/4 degree's to get a slight interference fit so it would touch the outer edge first. This will allow the valve to be elastic enough to stretch it lengthwise a hair, allowing it to keep the seat self cleaning as it rotates. You cant believe how many shops do it the other way, and put a full 1 or 2 degree interference angle on them. This allows the valve to "slam" and with no springboard effect, pounds out the seats fast, due to the "guttering" effect it causes. I used the stones as a final touch to get the vac to hold. Without, machined seats have a hard time holding a vac on their own, no matter what you may hear from the shop doing the valve job, and the hype from Serdi, Winnona, Kwik Way, etc. The cutter is so fast, the profit is much larger, due to time constraints. Would you run your rings on freshly bored cylinders? No, you know they need to be honed with a stone to get the best seal. A cutter still tears metal away, even with the slightest pressure. Lapping compound can help, but only if you get Clover brand extra fine. That Permatex crap is good for nothing modern. |
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This thread, so far...
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