Good video. There's another video about this but the guy actually did multiple back & forth passes, and obviously only the first would be guided by the pilot shaft & subsequent passes could be offset.
So what's an acceptable clearance, 2, maybe 3 thousandths. I'm curious because I need to know which reamer to order, in running 11/ 32 valve stem. I believe that's .341.
Good video on how NOT to do it. This method has fail written all over it. No accuracy, no proper measurement instruments. We're talking about 0.001" clearance here between valve and guide. How exactly are you going to measure that? And how do you know that what you just did hasn't made it worse, if you can't measure it acurately? Fail, fail, fail.......
He also is using bronze guides in a cast head. It will stick unless you clearance it to the max of the spec, defeating the purpose of renewing a worn guide. A modern cast guide (chilled cast iron) will last every bit as long as a bronze guide and will have proper the heat dissipation so it will not seize like a bronze guide and can be set up with proper clearance.
Some thought required here.......Assuming bronze guides were driven in place, an extra step[common sense] should have been taken to prevent end of guide distortion from install blows. Then maybe reaming entire length of guide would not be necessary. Also the method used he used here kneeling on ground with drill "centered" from the top is not even aligned "on center" down into the bore. This new guide is already gonna be tippy at the top third of it's length. The tool continues it's travel down the remainder of guide bore and begins to align, but it's already off center by .001 or more This is how you build a backyard "motor." Not a 20,000RPM Renault or Honda F-1 screamer. Maybe Instructors need to pay attention more, before uploads on tube sites. I would not want my kid going to this school.
Hi So when reaming out valve guide's do you have to use a reamer the same size as the valve stem?? or use a slightly smaller reamer than the valve stem??
i dont know if you take requests or not but i was wondering if you could make a video on how to drill out the old cast guides and press new ones in as a diy. im just a kid out of highschool and id rather learn how to do this by myself rather than blow all my cash to let someone else do it haha also what is the minimal tools i would need. thanks :) thumbs up so he can see this post! haha
Not good to use bronze guides in a cast head. It will stick unless you clearance it to the max of the spec, defeating the purpose of renewing a worn guide. A modern cast guide (chilled cast iron) will last every bit as long as a bronze guide and will have proper the heat dissipation so it will not seize like a bronze guide and can be set up with proper clearance. Bronze in aluminum ok, not in cast iron.
Awesome vid! I just have a question for clarification. The valve stem to guide clearance should be about .002 inchs. when you ream the guide and remove material is it only removing material in the tight spot to keep the same clearance? would this mean that you use the same size reamer as the guide? Thank you :D
