That it is, Bob!
And tons more fun than laying tile...
And tons more fun than laying tile...
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XS1B Engine Teardown
- Thread starter Jim
- Start date
I have only glossed through this write-up cuz I'm off to do other things and I hadn't seen @Mailman's reaction, but turns out that @Mailman stole the words I had in mind...HOLY COW!!! I'll give this write-up the attention it deserves a little later tonight.Holy Cow! That’s a lot of work! But I suspect that’s your kind of fun!
That's outstanding work. Well done with the improvisation. It's going to be a perfect repair by the look of it.
Appreciate that!
I looked up the bearing strength of the 6061 and cast ally, and the 6061 was about 25% stronger iirc. So hopefully a bit better than stock.
Still curious as to why just 1 out of 4 bores?
Possibly an issue with the casting in that area. Maybe long term too tight valve clearance contributed to the wear. Truth is, as often the case, the subsequent failure obliterates the evidence of what initially caused the failure.Appreciate that!
I looked up the bearing strength of the 6061 and cast ally, and the 6061 was about 25% stronger iirc. So hopefully a bit better than stock.
Still curious as to why just 1 out of 4 bores?
If you have access to liquid nitrogen I recommend you shrink the machined bush and drop it into place with an interference fit. A thou to thou and a half should be plenty interference. But cooled in liquid nitrogen it'll drop straight in. Leave it overnight to warm up to ambient, you can then ream it to finished size. Hope that helps.
Edited to say - Plan B in the absence of liquid nitrogen. Bake the rocker box in the oven to around 90 to 100 Celsius. Freeze the machined bush in the freezer, that should get it down to maybe minus 15 Celsius. That should do it. But in case the bush sticks part way in, have a plan to press it into place before you start inserting it.
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1.) I'd ditch the calipers and grab a micrometer when measuring the telescoping gage.
2.) I'd take whatever you measure that bore with, using your inch micrometer, and add .005".
3.) I'd put the bushing in the freezer overnight, and heat the head up with the oxy torch before throwing the bushing in it.
4.) [Optional] Buy yourself a friggin Bridgeport!
2.) I'd take whatever you measure that bore with, using your inch micrometer, and add .005".
3.) I'd put the bushing in the freezer overnight, and heat the head up with the oxy torch before throwing the bushing in it.
4.) [Optional] Buy yourself a friggin Bridgeport!
Are you going to use a 609 or similar locking agent. Probably not needed if it's an interference fit.
I do my best engineering in my dreams. Seams I wake up with plans in my head after thinking about it for days. Anyone else do that
I do my best engineering in my dreams. Seams I wake up with plans in my head after thinking about it for days. Anyone else do that
I have used "dry ice" from a CO2 fire extinguisher to shrink valve seats. Line a small cardboard box with pieces of styrofoam or other foam insulation, put the extinguisher nozzle in the box, and release it. Put the part to be shrunk in the "snow", and put a foam piece as a lid over it. "Dry ice" holds minus 78C.
Amazing what you can do to get the job done when you have to.
Normally I'd agree. When I measure something like a crank journal where I'm looking for a very specific dimension, a 3 or 4 digit mic is all I use.
Here, I'm not worried about a specific number... the exact dimension is immaterial. What's important is I cut the bush exactly .005" (your number) larger than the hole. That's easily doable with a caliper.
Yes. Already on hand.
I have years of experience using liq nitrogen on Boeing aircraft gear bushings, so that was my first thought also... unfortunately, no access any more.
Always have a plan B.
Good idea, however, have you looked at the price of Co2 extinguishers lately? Holy crap!!
Found a welding supply 10 min away that sells dry ice. Minimum order is 10lbs at $16... in stock... walk in, walk out. So I'm gonna go about 400°f in the oven for a couple hours and dry ice the bush for the same amount of time. That should do it.
Cheers.
Cheers buddy.
Just make sure to have really good ventilation....10 lbs of dry ice becomes a huge volume of CO2. In a small space that can be lethal. But I am sure you are well awareGood idea, however, have you looked at the price of Co2 extinguishers lately? Holy crap!!
Found a welding supply 10 min away that sells dry ice. Minimum order is 10lbs at $16... in stock... walk in, walk out. So I'm gonna go about 400°f in the oven for a couple hours and dry ice the bush for the same amount of time. That should do it.
Cheers.
Impressively ingenious work there, @Jim ! (particularly the means of finding the center of the bore). Although I'm not a machinist by trade or training, based on my own experience with press-fits, I would say anything more that .0015" interference is asking for trouble, especially on such a relatively small bore. Getting the bushing in its bore perfectly square strikes me as important. For that reason, I would make some form of a pilot with a shoulder to line up that bushing. Good luck!
Agreed. I think I'll waste 16 bucks on the dry ice and test freeze the test bushing I made just to measure how much shrinkage I get. Then heat the box and measure how much expansion I get. Sum those two numbers and add about 1 thou". That should get me a nice tight fit.
An 18 hr soak in my freezer shrunk exactly .002" off the test bushing diameter. That ain't bad.
