aerocarb for Jabiru CH750 - Zenith Aircraft Builders and Flyers2024-03-28T09:03:50Zhttps://zenith.aero/forum/topics/aerocarb-for-jabiru-ch750?commentId=2606393%3AComment%3A869849&x=1&feed=yes&xn_auth=noI installed the Aeroinjector,…tag:zenith.aero,2022-05-22:2606393:Comment:8698492022-05-22T16:38:13.566Zjerry nicholshttps://zenith.aero/profile/jerrynichols
<p>I installed the Aeroinjector, did the tune procedure, and discovered it was within specs right out of the box! 100 degree drop from lean to rich at full power. I didn't even open the adjustment tab but took off for a test flight. At about 500 feet RPM began backing off and I was looking for a place to set it down. I took a chance and started leaning; that brought the RPM back up to almost full power. After a normal landing I retested the tuning and it was so rich it would hardly idle. …</p>
<p>I installed the Aeroinjector, did the tune procedure, and discovered it was within specs right out of the box! 100 degree drop from lean to rich at full power. I didn't even open the adjustment tab but took off for a test flight. At about 500 feet RPM began backing off and I was looking for a place to set it down. I took a chance and started leaning; that brought the RPM back up to almost full power. After a normal landing I retested the tuning and it was so rich it would hardly idle. When I did remove the plastic cap on the needle adjustment, I discovered that there was no "set screw"; the needle carrier was free to move and had backed out to a rich position. I found the "setscrew" in the throttle body. I retuned but full power was less than before. </p>
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<p>I couldn't adjust the needle carrier to a leaner position. The Aerocarb tech suggested I return the slide and carrier for their inspection. They judged the carrier and slide as "incompatible". A different slide worked with my carrier and a different carrier worked with my slide; but, they didn't work together. They sent back a different carrier and adjustments were possible.</p>
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<p>I was able to make adjustments but still couldn't get full power. After a lot of head scratching, I took a close look at the Aerocarb air filter element. It was almost fully blocked. Even pressurized air blowing through the element could hardly be felt by a wet finger. I don't know whether the filter came that way or if it was contaminated by the rich fuel mixture. There was no soot in the manifold or carb body.</p>
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<p>I guess it's too late to make a long story short but after weeks of trouble, I'm flying again!</p>
<p></p> Great info; thankstag:zenith.aero,2021-11-06:2606393:Comment:8523702021-11-06T15:54:06.016Zjerry nicholshttps://zenith.aero/profile/jerrynichols
<p>Great info; thanks</p>
<p>Great info; thanks</p> Jerry,
Like you, I needed a p…tag:zenith.aero,2021-11-06:2606393:Comment:8522252021-11-06T01:45:38.730ZJohn Austinhttps://zenith.aero/profile/JohnLAustin
<p>Jerry,</p>
<p>Like you, I needed a project and love to experiment, so I switched from the Bing to an AeroInjector (latest version of AeroCarb). I have 100's of hours experience with it in my STOL CH750/Jabiru 3300 and have a lengthy, detailed thread in the forum located here: <a href="http://www.zenith.aero/forum/topics/airbox-weight-jabiru-fwf-kit-for-zenith-aircraft?id=2606393%3ATopic%3A551990&page=1#comments" rel="noopener" target="_blank">AeroInjector TBI Carb…</a></p>
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<p>Jerry,</p>
<p>Like you, I needed a project and love to experiment, so I switched from the Bing to an AeroInjector (latest version of AeroCarb). I have 100's of hours experience with it in my STOL CH750/Jabiru 3300 and have a lengthy, detailed thread in the forum located here: <a href="http://www.zenith.aero/forum/topics/airbox-weight-jabiru-fwf-kit-for-zenith-aircraft?id=2606393%3ATopic%3A551990&page=1#comments" target="_blank" rel="noopener">AeroInjector TBI Carb</a></p>
<p><a href="https://storage.ning.com/topology/rest/1.0/file/get/9772902688?profile=original" target="_blank" rel="noopener"><img src="https://storage.ning.com/topology/rest/1.0/file/get/9772902688?profile=RESIZE_710x" width="300" class="align-full"/></a></p>
<p>Not required, but I used a McFarlane "vernier assist" throttle and a "vernier assist" mixture control. These allow you to make coarse adjustments without any sort of lock or button and then have a vernier action for fine adjustments. However, you will have to have a throttle direction reversing bell crank or devise some sort of mechanism to operate the slide on the AeroInector "backwards" since the throttle action is reverse of conventional carbs. I made my own reversing bell crank which is described here: <a href="http://www.zenith.aero/profiles/blogs/throttle-reversing-bell-crank" target="_blank" rel="noopener">Throttle Reversing Bell Crank</a></p>
<p><a href="https://storage.ning.com/topology/rest/1.0/file/get/9772903694?profile=original" target="_blank" rel="noopener"><img src="https://storage.ning.com/topology/rest/1.0/file/get/9772903694?profile=RESIZE_710x" width="300" class="align-full"/></a></p>
<p>That's a lot of information to digest but I recommend you read the entirety of each thread. But, to summarize the key points:</p>
<ol>
<li>The Aeroinjector works best with gravity feed <em>only</em> - no problem with the STOL 750 since it's a high wing plane!</li>
<li>Since the AeroInjector doesn't have a fuel bowl, vapor bubbles will cause "burps" or hesitancy. To avoid this, keep the fuel line as short as possible firewall-forward (to avoid heat soaking), insulate the fuel line with fire sleeve and a heat reflective line wrap, and the line must be routed always upwards toward the carb with no high spots to trap vapor bubbles.</li>
<li>The AeroInjector doesn't fully shut off even with the throttle closed and the mixture pulled full lean - it'll slowly drip after shut down - so develop the habit of killing the engine by shutting the fuel selector valve to "OFF."</li>
<li>As mentioned, you'll need either a throttle reversing bell crank or some other mechanism to operate the carb "backwards" so the throttle will operate conventionally with pull to close and push to open.</li>
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<p>If done correctly, I've found it to be a very predictable and dependable carb and my EGT balance improved. Installation allowed removal of the airbox and carb heat muff for a total weight savings of 8 lbs (that Bing is heavy!). I like having a mixture so I can deliberately run the engine rich when additional cooling is needed in a hot and long climb, etc. I get slightly better fuel economy in cruise. I wouldn't consider going back to the Bing now that I have mine so well dialed-in!</p>
<p>John</p>
<p>N750A</p>
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