Showing posts with label carburetor. Show all posts
Showing posts with label carburetor. Show all posts

Sunday, April 26, 2009

A glimse of my insanity.

Here's an example of the kind of insanity I do. Kind of a long one, so get comfortable.
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I have been using a mechanical fuel injection system with methanol alcohol fuel on my dragster. For a couple of reasons, I have decided to change over (or back, really) to a carburetor and gasoline. Basically, the injector and the alcohol fuel system need a lot more maintenance, so I'm switching. This is the top part of the fuel injector. You can see the injector nozzles and lines near the bottom, these spray the fuel directly into the intake ports. The top part is the air metering scoop, or "hat", and the red butterfly valve plates tilt open and let the air in. The red plates and the openings are very carefully machined and fitted. They, and the rest of the system, are much more sophisticated than they look.
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This injector is made by a company called Enderle, and this style and look of injector has been in use for probably 40 years. For what it's worth, it has a serious appearance. When a car shows up with one of these, it means business. Yeah, it's part of the allure.
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Here (below) is the gas carburetor, and a high flow air filter. I love using an air filter. I like the security of knowing no pebbles or debris can get in my engine. Even dust is bad. The only problem, really, is the comparitively pedestrian appearance of this setup. Doesn't exactly scream formidable, does it?
What to do? What to do, indeed?

I made this air filter cover/ air scoop out of .030 aluminum sheet. All it really does is cover the filter, and direct incoming air onto the filter. Kind of crude, but the rounded bends are supposed to soften the boxy look. It's supposed to emulate an injector hat made by Crower, but it's kind of big. That's as small as I could make it and still cover the filter. Notice the word emulate, that will be important later. I still really like this, but it still looked boxy to me, so I tried a couple of more ideas.
Here is a more faceted design model, made of cardboard. The middle shelf would not be in the final design, it's only there for support. I thought the facets, and bent sides would help hide the tall height of the scoop; the filter is 5" tall. I decided this was too complicated, and did not make it in metal.
Here's a half-scale model I made out of file folder material. I really liked this design, and this material and size made the model more accurate, and easier and faster to build. Doesn't photograph well. And yeah, it kind of looks like a McDonalds large french fry box.

I did build this one. I modified some of the angles and dimensions to soften it up a little, make it less radical. One nice feature of these aluminum scoops is that the top surface functions as the top filter covering, they sit right on the top of the filter top edge. This keeps the overall height down.
Here's a rear 3/4 view of the last one. I have this little bench top sheet metal brake (bender). Works good enough for these little projects, I think. Overall, I was pretty happy with this one. It has nice faceting, it tapers towards the rear, it has the nice strengthening bends across the top and bottom of the front opening, and the angled front side openings give it some agressiveness. On the downside, it might be too busy, and I think the overall look is too Star Wars. Not simple enough to fit in with the late '60's early '70's vibe I'm going for.

Finally, this. (Sigh). This is an air filter housing designed to look like an Enderle injector. Guys buy these and put them on their street cars to give them some of the appeal of a real injection system. But obviously, they're fake. These have all the sophistication of the auto accessory aisle at K-Mart. And I hate fake stuff on cars. I really hate fake stuff on race cars. So, what I did was, I bought this used on ebay, and hollowed out the bottom, and made some sturdy brackets so it would fit over the air filter, and well, there you have it. You can see the air filter poking out at the bottom a little, but I don't care about that. Yes, I made a rod from the carburetor linkage so the butterfly plates open as you push the throttle pedal. Good grief, what have I come to?
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I know this looks the same as the real injector in the photos, but trust me, it's different, and it's fake, and it's junk. But it does get me some of my cool look back, and that was why I did it. Other downsides: It would take longer to get off and on if I have to do any work on the carburetor. It is connected to the throttle linkage, and why connect anything to the throttle linkage if you don't have to? Finally, it is fake. I'm not fooling anyone, least of all myself. Yet people that know me, know I sometimes like to do odd things just to do them. I don't like to take anything too seriously. So maybe it's okay.
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I'm either going with this fakery, or a better version of the first scoop (3rd photo). Perhaps I'll get the courage to just run the air filter alone (2nd photo). I kind of like the simplicity, purity, and honesty of that.
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I also found another cardboard model, and of course there were countless sketches. The insanity of this is that I went through all of this, and all of these permutations, and physically made all of these, in only a week's time. I'd be up all night, making sketches. Do this, no I like that, no, I don't like that, how about this, what if this, no, I'll just do something fake. It was crazy, and yet it seemed ordinary to me. It was like I was compelled to do all of this. I couldn't not do it. It's just how I am.

Sunday, July 27, 2008

Carburetor clean-out update

I was very disappointed that the truck would not start after my meticulous carburetor clean-out. I began basic troubleshooting and discovered that I had inadvertently broken the positive side coil wire off from it's terminal. Badly crimped wire terminal; how surprising.
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A quick strippy-strip, and a crimpy-la-do-da, turn the key, and the the engine roared to life. The carb is really running nice now. It was running so much better that I had to turn the idle way down. See, when an engine begins to have problems, one way to keep it running is to turn up the idle. This merely masks the problems and is not correct.
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I drove the truck around for awhile to get a feel for it. I think it needs a new transmission input bearing (not a tough job), and some brake work, since it darts around under braking. But it drives pretty cool. Probably looks cool too. I think I'll take it to some cruise nights soon.

Saturday, July 19, 2008

Carburetor clean-out

The F100 will not start. I took the carburetor off to see if there was a fuel problem. I pulled the carb apart enough to find this little gem, a 1/4" lock washer, jammed in the air door assembly of the secondaries:This was no doubt accidentally dropped in when someone was working near there. The secondaries would never work right with that in there, but it could have been worse; it could have dropped into the venturi, and gone down inside the engine. That would leave a mark. Besides, this is not the reason it will not start.
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I found a lot of dirt inside the carb. A surprising lot. I was going to take a photo of it, but I figured you know what basic dirt looks like. I cleaned out all the little orifices I could, generally cleaned everything else, and checked for broken parts. When it came time to reassemble it, I found that the center gasket was unsalvageable; a careful disassembly had nonetheless torn it apart. This is a problem with taking a carb apart, the body gaskets tear very easily and are rarely reuseable. Since I did not have spares for this carb on hand, I mail ordered a pack of 5.
Here's a new gasket on the left, with the top of the carb upside-down beside it, and a tube of white grease at the bottom. The black paper gasket has a light glare on it in this photo, but it is indeed black.

Here's what I do; I smear a light coat of the white grease on both sides of the gasket before assembly. Sometimes, this will keep the gasket from sticking to the parts the next time they are taken apart, so the gasket can be reused. It's not just a cheapness thing; if you dug into the carb as part of a roadside repair, you'd likely tear the gasket, and not have a new one to replace it.
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Anyway the white grease doesn't always work, but it's worth a shot. Errant grease will dissolve in the gas, so don't worry about it. Might help your mileage or something, I don't know.

Here is the carb all back together. You can see the thin white line going around the carb body where the new gasket is. I am still getting familiar with this style of carb, it's similar to the Rochester Quadra-jets that came on many GM cars. One nice thing about these is part of the design: the main carb top comes off, as shown in the 2nd and 3rd photos, and most everything is accessible right there. The carb top gasket that we've been talking about is horizontal, not vertical like the 4 separate gaskets on Holley carbs, and it's above the fuel level, so it should never leak under normal conditions.
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I did not have time to try starting the truck, so cross your fingers for later in the week.
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I'll leave you with an additional bodge I found while troubleshooting. The silver-colored end of this coil wire is supposed to look like the brass-colored end. Instead, it's all folded and crimped up to fit (jammed) into the coil end terminal. Sloppy fit, and I'm surprised if this ever worked better than intermittently as it was was doing for me. I mean, who does this?