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| | | | Joined: Aug 2006 Posts: 29 New Guy | | New Guy Joined: Aug 2006 Posts: 29 | I have a 1991 350 engine that I am working on to put in my 63 and I have a question. I took the valves out and want to clean the seats up. My Uncle has the machines to do the job, but can only do a 45 deg seat angle and my specs show it as a 46 deg angle. My Unlce thinks it will work OK, but I have never done this before, what do you guys think?
Thanks. | | | | | Joined: Feb 2004 Posts: 29,841 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,841 | The factory specification calls for a 45 degree valve angle, and a 46 degree seat, what's known as an "interference angle" where there's a single line point of contact at the upper edge of the valve face. It's basically a quick assembly trick at the factory because they don't have to be concerned with exact seat width.
If you choose to use a 45 degree seat on both valve and seat, you'll also need to use a 30 degree upper angle on the seat, and a 60 degree lower angle. That determines the exact width and position of the seating face. The 3-angle method is a much better choice, but it's time-consuming, and you have to have 3 different seating stones for each valve size.
Intake seats need to be .060" wide, and exhausts need to be .090", if you choose to do an exact match on valve and seat angles. Unless you're racing, the interference angle is adequate for most applications.
Jerry
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| | | | | Joined: Aug 2006 Posts: 29 New Guy | | New Guy Joined: Aug 2006 Posts: 29 | Jerry,
Can you tell me what would happen if we did a 45/ 45 without doing the three angle method? My Uncle thinks that since other engines use the 45/45 it won't be any big deal. I have no experience with this and need to learn the facts. I need to know if the three angle is a 'best' practice method or if it means the valves will go bad after a short period of time if we do a 45/45.
Thanks for your help.
Rick | | |
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