Thread: Piston clearance??

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Originally Posted by Louey

Now I'm going to tease ya...Take that sign out of there...

Why should I take that sign out of there? You must have noticed where I edited my signature earlier? Yes it did say earlier today that I was a high shool automotive technology instructor. They closed my program this year due to funding and more programs are on the chopping block next year. I didn't have to be a machinist to teach the class and as far as that goes engine repair isn't even required by the National Automotive Technicians Foundation to be taught on the high school level. Actually it is often discouraged due to the fact that we are required to teach brakes, suspension and steering, electrical and electronics, and engine performance and a student could only take the class six semesters. I have worked a long time as a tech but I have generally left the machine work to someone else except for running a brake lathe. My precision measuring is generally not so precise and limited to measuring brake rotors and drums to make sure they aren't warped or too thin and measuring spark plug gap and a/c compressor clutch air gap and that sort of thing. I am not usually looking for and exact number but for a number that falls within a set of specifications. Definately not stuff that is to the nearest ten thousandth and not as precise as engine machining. I use a vernier caliper, dial indicator, feeler gauge, torque wrench, and a measuring tape quite often, but a micrometer very seldom. I have access to some machine shop equipment and I'm trying to learn more about it on my own stuff. I might be messing it up but oh well, it's mine and i have to learn some how or I can just give up all together and never learn it. I learned this time that blocks aren't always bored dead on 20, 30, 40, or 60 over, and its a good idea to measure the piston in the right spot to get the correct reading. I only measured on place and I didn't realize they had as much taper as they do so I was off a tad. I'm reading up on the benifits of torque plate honing as well as many other things. My neighber is a retired machinist in his 80's and I guess he did a lot of stuff the old school way. The equipment is pretty old but it has been used to build countless engines. I had him bore a 300 six for me with his old bar and honed with no torque plate and it had over 300,000 on it the last time I saw it. He machined one for us in the 90's for our mini-stock car that won the track championship six years in a row and the engine turned 9800 rpm every lap. Of course we broke it a couple of times but the crap worked. I didn't know his techniques weren't correct.....the crap just worked and very well. We were blowing the doors off the stuff being machined by the other shops doing it the "correct" way. I didn't know there was anything "wrong" with the engine that's been in my '35 for close to 15 years now until recently. You sure can't tell by the way it runs. It makes good power and doesn't knock, smoke, or use oil, but according to some it is a piece of junk because it wasn't honed with a torque plate. It was bored with a antique quick way boring bar to size and just lightly honed before assembly. I didn't know until I started digging deeper into this stuff that it was unacceptable to do that. The crap he did worked on a lot of engines for a lot of people that's all I know. Now I know it's not the right thing to do and his grandson and myself are looking into trying to update a few things. The old timer told me he was looking into getting torque plates around the time he closed the shop but decided to retire. I'm actually enjoying learning more about this stuff. It's quite a challenge. We just learned how to set up the surfacing machine Saturday and we replaced the rock and figured out how to dress it. We played with an old 302 block and milled the decks. We are going to try to set up an old junk head next and mill it. As far as the ASE master tech thing goes...it is what it is. I passed all the tests the first time with flying colors. I'm proud of that. I know what I know and what I don't I can learn. I guess that means I don't know everything.