BOLTS - If It Doesn't Fit...
...DON'T force it!
I had a project at the shop this evening that was supposed to be quick and simple: Swap out a dead engine on a little pressure-washer. It's just a pressure-pump bolted to the mounting boss, and the engine bolted to the metal frame. 8 bolts, should take less than an hour...
Except, that the bolts for the mounting boss don't fit into the holes of the new engine. None of the bolts I have on hand fit either. What the heck are the dimensions of these things? You'd think they'd be pretty much universal... Briggs & Stratton uses mounting bolts that are 0.312-24. The shaft is threaded 5/16-24. 5/16 = 0.3125. I checked with a knowledgeable friend, and he said that the extra 0.0005" would not make a difference. Ok, but when I tried the bolts, they still didn't feel right. Did some checking, and it turns out the bolts I have are 18 threads per inch, not 24! Good thing I checked. To the naked (and untrained) eye, there's not a lot of difference, but it's there.
The original engine was a Honda GC-135, so I pulled up the specs on it; Turns out it is tapped M8x1.25. You can use a 5/16-24, but the metric bolt is preferable. My friend (Andy) actually came over, since he had the bolts in his shop. We tried the 5/16-24 first, but it still didn't feel right, but when we tried the M8x1.25, they fit perfectly. The replacement engine, I should have mentioned, is a Power-Fist, which is one of the many Honda clones out there. It makes sense that being a Honda clone, it would use the Honda specifications for the mounting boss.
While I've been tinkering with engines since I was six years old, swapping out things like this is new to me, and I've never had anyone explain to me what all the thread-counts and such meant on bolts and their matching connections. Imperial bolts, measured in inches, are based on threads-per-inch; So a 5/16-24 bolt is 5/16" in diameter, and has 24 threads per inch. By comparison, a Metric bolt is measured in millimetres, both for the width, and the pitch between the threads. So a M8x1.25 means that it is 8mm in diameter, and the threads are 1.25mm apart. I did not know this until today.
By the time we got all this straightened out, it was too late to bother continuing for the evening (past 9pm.) I will finish the job next time, when I'll also have time to add gas and oil, and make sure everything actually works.
I also worked on an Arctic Cat ATV this afternoon. This was a simple "change the oil please" job, which is something that I can do, even with my very limited experience with these machines. Seems that the company that sold the machine to the guy is too busy servicing farm machinery to bother with a "small job" like changing the oil in a customer's machine, so he brought it to me. I can see why they wouldn't want to tie up one of their combine-technicians on something like this, but... In any case, more income for me! Not just labour either; I sold the customer 4 bottles of Amsoil 0W-40 motorsports oil (three in the machine, and one extra) as well, so it was a profitable venture. Next time, I'll have that much more experience with these machines, so the job will be that much faster and thus even more profitable.
One of these days, I'm going to have to hire someone to work as a power-sports technician.
I had a project at the shop this evening that was supposed to be quick and simple: Swap out a dead engine on a little pressure-washer. It's just a pressure-pump bolted to the mounting boss, and the engine bolted to the metal frame. 8 bolts, should take less than an hour...
Except, that the bolts for the mounting boss don't fit into the holes of the new engine. None of the bolts I have on hand fit either. What the heck are the dimensions of these things? You'd think they'd be pretty much universal... Briggs & Stratton uses mounting bolts that are 0.312-24. The shaft is threaded 5/16-24. 5/16 = 0.3125. I checked with a knowledgeable friend, and he said that the extra 0.0005" would not make a difference. Ok, but when I tried the bolts, they still didn't feel right. Did some checking, and it turns out the bolts I have are 18 threads per inch, not 24! Good thing I checked. To the naked (and untrained) eye, there's not a lot of difference, but it's there.
The original engine was a Honda GC-135, so I pulled up the specs on it; Turns out it is tapped M8x1.25. You can use a 5/16-24, but the metric bolt is preferable. My friend (Andy) actually came over, since he had the bolts in his shop. We tried the 5/16-24 first, but it still didn't feel right, but when we tried the M8x1.25, they fit perfectly. The replacement engine, I should have mentioned, is a Power-Fist, which is one of the many Honda clones out there. It makes sense that being a Honda clone, it would use the Honda specifications for the mounting boss.
While I've been tinkering with engines since I was six years old, swapping out things like this is new to me, and I've never had anyone explain to me what all the thread-counts and such meant on bolts and their matching connections. Imperial bolts, measured in inches, are based on threads-per-inch; So a 5/16-24 bolt is 5/16" in diameter, and has 24 threads per inch. By comparison, a Metric bolt is measured in millimetres, both for the width, and the pitch between the threads. So a M8x1.25 means that it is 8mm in diameter, and the threads are 1.25mm apart. I did not know this until today.
By the time we got all this straightened out, it was too late to bother continuing for the evening (past 9pm.) I will finish the job next time, when I'll also have time to add gas and oil, and make sure everything actually works.
I also worked on an Arctic Cat ATV this afternoon. This was a simple "change the oil please" job, which is something that I can do, even with my very limited experience with these machines. Seems that the company that sold the machine to the guy is too busy servicing farm machinery to bother with a "small job" like changing the oil in a customer's machine, so he brought it to me. I can see why they wouldn't want to tie up one of their combine-technicians on something like this, but... In any case, more income for me! Not just labour either; I sold the customer 4 bottles of Amsoil 0W-40 motorsports oil (three in the machine, and one extra) as well, so it was a profitable venture. Next time, I'll have that much more experience with these machines, so the job will be that much faster and thus even more profitable.
One of these days, I'm going to have to hire someone to work as a power-sports technician.