Matt Mead
Well-Known Member
- Joined
- Feb 28, 2022
- Messages
- 78
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- 65
I'm replacing the entire fuel system on my 1987 OMC 175 (Evinrude 175 Crossflow E175TLCUA) including rebuilding the carbs as best I can. I get to the float bowls and the fuel inlet is a proprietary plastic/brass hybrid 90° fitting and all 3 are cracked. Awesome.
I tried twisting them out and they don't budge, so I had to literally drill them out. That's when I realize they are an interference fit. Well that's going to be awesome to reinstall.
If you look on all the parts diagrams this fitting is curiously missing. It doesn't matter which sub-assembly you choose, it ain't there. They want you to buy the whole float bowl for ~$175. Uh, no.
https://www.marineengine.com/parts/...LCUA&manufacturer=Evinrude§ion=Carburetor
I found this thread and a few others where people went full MacGyver on it and pressed in Harley upgraded brass elbows or went with a 1/8" NPT setup. But I didn't quite like the compromises. After much searching I found ONE dude who went to the factory when it closed and bought these: https://www.ebay.com/itm/111788930652
I figured I hit the jackpot, looks exactly like what I drilled out. Well, turns out it's not EXACTLY what I drilled out, the brass part is just slightly longer than what it needs to be, but I'm pretty damn sure it will work. Why? Because I attempted to press-fit/shrink-fit these suckers on a 4-5 thou interference fit, lol.
Yeah, I did way too much measuring with my dial calipers, micrometer and way too much researching on the net on what the different tolerances should be for certain fit ups, plus the thermal expansion coefficients of aluminum and brass. Plan was to heat the aluminum bowl up with my torch and freeze the brass in the freezer. A little 3-in-1 oil as crappy assembly lube and 30 strikes from a hammer later, they were "in".
You'll notice they sit proud of the hole and luckily it doesn't matter because there is a huge pocket on the other side where it mates up. I never was able to sink them all the way down, because 4-5 thou is WAY too much for a press-fit/shrink-fit operation of this type and I got tired of smacking it while the heat transfer and friction slowed all progress. There is an o-ring that sits on the brass shaft OD and is supposed to squish between the plastic and the bowl. It ain't squished and I don't care, because these fittings aren't leaking, lol. It's essentially cold welded in there, haha!
I knew I couldn't just hit the plastic, even if it's pretty strong Polyoxymethylene (POM) or whatever it's made of. So I found a little wrench that would distribute the load of the blows. I'm glad I did, because it needed way more force than I thought.
It's not a perfect fix. I made tons of mistakes, as I usually do. However, I know what I would do next time. I tried running a regular drill bit through the holes to make sure they were at least to rough dimension. The real way is to ream them. I have never owned any reams, but this might be the time to start buying some. Also, since people on forums and calculators recommended 0.5 thou to 1 thou, *maybe* 2 thou maximum interference fit I still needed to remove material. I wanted to remove some from the brass, but how? I don't own a lathe that could chuck that nipple up and the ghetto drill chuck idea didn't seem like it was going to work. Hand sanding it? Wouldn't it be oval real quick if you tried? I dunno. So I ran out of patience and just tried.
This is what separates the home gamers like me, from the pro's. I still like being a home gamer shade tree mechanic, though.
Now if I didn't shoot a $16 brass jet across the garage with compressed air and lose it I would probably know by now if this motor runs. Oops! Oh well, what's another week and half waiting for parts to ship to Bullhead again?
I tried twisting them out and they don't budge, so I had to literally drill them out. That's when I realize they are an interference fit. Well that's going to be awesome to reinstall.
If you look on all the parts diagrams this fitting is curiously missing. It doesn't matter which sub-assembly you choose, it ain't there. They want you to buy the whole float bowl for ~$175. Uh, no.
https://www.marineengine.com/parts/...LCUA&manufacturer=Evinrude§ion=Carburetor
I found this thread and a few others where people went full MacGyver on it and pressed in Harley upgraded brass elbows or went with a 1/8" NPT setup. But I didn't quite like the compromises. After much searching I found ONE dude who went to the factory when it closed and bought these: https://www.ebay.com/itm/111788930652
I figured I hit the jackpot, looks exactly like what I drilled out. Well, turns out it's not EXACTLY what I drilled out, the brass part is just slightly longer than what it needs to be, but I'm pretty damn sure it will work. Why? Because I attempted to press-fit/shrink-fit these suckers on a 4-5 thou interference fit, lol.
Yeah, I did way too much measuring with my dial calipers, micrometer and way too much researching on the net on what the different tolerances should be for certain fit ups, plus the thermal expansion coefficients of aluminum and brass. Plan was to heat the aluminum bowl up with my torch and freeze the brass in the freezer. A little 3-in-1 oil as crappy assembly lube and 30 strikes from a hammer later, they were "in".
You'll notice they sit proud of the hole and luckily it doesn't matter because there is a huge pocket on the other side where it mates up. I never was able to sink them all the way down, because 4-5 thou is WAY too much for a press-fit/shrink-fit operation of this type and I got tired of smacking it while the heat transfer and friction slowed all progress. There is an o-ring that sits on the brass shaft OD and is supposed to squish between the plastic and the bowl. It ain't squished and I don't care, because these fittings aren't leaking, lol. It's essentially cold welded in there, haha!
I knew I couldn't just hit the plastic, even if it's pretty strong Polyoxymethylene (POM) or whatever it's made of. So I found a little wrench that would distribute the load of the blows. I'm glad I did, because it needed way more force than I thought.
It's not a perfect fix. I made tons of mistakes, as I usually do. However, I know what I would do next time. I tried running a regular drill bit through the holes to make sure they were at least to rough dimension. The real way is to ream them. I have never owned any reams, but this might be the time to start buying some. Also, since people on forums and calculators recommended 0.5 thou to 1 thou, *maybe* 2 thou maximum interference fit I still needed to remove material. I wanted to remove some from the brass, but how? I don't own a lathe that could chuck that nipple up and the ghetto drill chuck idea didn't seem like it was going to work. Hand sanding it? Wouldn't it be oval real quick if you tried? I dunno. So I ran out of patience and just tried.
This is what separates the home gamers like me, from the pro's. I still like being a home gamer shade tree mechanic, though.
Now if I didn't shoot a $16 brass jet across the garage with compressed air and lose it I would probably know by now if this motor runs. Oops! Oh well, what's another week and half waiting for parts to ship to Bullhead again?
