Starting my Homemade Hackman

48 posts in this topic

Posted

Since I have the Avid home for some maintenance I decided it’s time to install the hack system I’ve been planning. I have gathered everything but the main jets. I added a mount plate next to the throttle for the controller and have installed the air port into the air cleaner. Since I’m running the older carburetors I have to add a vacuum port per Chris B. directions. I hope to get that done tomorrow. 

The directions call for 3/16 and 1/8 hose. I have 1/4 and 1/8. The 1/4 inch will be used from the air cleaner (clean air supply) and from the controller. The rest will be 1/8th. I plan to eliminate the two extra Tee’s and use a jumper hose between the carburetors like the Hackman system does. I’ll keep you posted on the progress and outcome. 

Still trying to figure out how big of a main jet change I need to make. At $20 for two new jets I’d like to get close the first round. I have a few sets of jets laying around and wonder if the opening sizes were posted somewhere. Would it be feasible to try and take a number drill set and make your own jets?

 

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Posted

I've drilled out jets for my Jabiru engine.  Need to used numbered drill bits most likely.  You could always work your way up if you need to go bigger.  JImChuk

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Posted

As close as I can tell I need to go from a 160 to a 180. I do have a good number set of drill bits. 

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Posted

I also need to source the carburetor hose fitting needed for the vacuum port. 

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Posted

looking at this chart, and doing some math tells me that a #50 drill bit is the same size as a 180 (1.80 MM) jet.  1.80 x .0394= .0709.   A number 50 drill bit measures .0700.   JImChuk

www.gridgit.com/postpic/2010/05/number-drill-bit-size-chart_513831.png
 

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Posted (edited)

Here is the jet sizing chart snatched from http://www.ultralightnews.ca/bing/bingjetchart.html

One thing I noted is that the temp is the carb inlet temp, which can be a lot warmer than ambient air. My 670 has at least 10 deg F temp increase at the carb (I used my wife's meat thermometer to check) so I jetted it for the warmer temp.

 

 

jets.jpg

jets 2.jpg

Edited by nlappos

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Posted

Interesting that this chart shows a 145 jet for the 582 DC.  I'm sure the CPS catalog chart shows 165 for the standard sea level main jet for a 582.  JImChuk

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Posted

Interesting that this chart shows a 145 jet for the 582 DC.  I'm sure the CPS catalog chart shows 165 for the standard sea level main jet for a 582.  JImChuk

Old data, I pulled it down, the right one says 165 and posting it now.

 

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Posted

A jetting chart won’t do me any good here as I have to up size the main jet for with the Hac System installed which these charts do not account for. I think I’m currently running 165’s. 

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Posted

Vance,

Ask Joey what the jet size is. As for drilling, I think I remember reading not to because of the chamfering on both sides of the jet is peculiar to each size jet.  I could be wrong on this, but is it really worth the hassle and maybe $$ from smoking an engine over. Good Luck

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Posted

Thank you BryceKat. You are correct. I was modifying a few parts of the system based on things I already had. I re-evaluated the plans and orders the 3/16 line and fitting per the plans. Also, I figure I can take the main jet spread between the two systems I know are working and get pretty close on proper main jet application. 

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Posted

A jetting chart won’t do me any good here as I have to up size the main jet for with the Hac System installed which these charts do not account for. I think I’m currently running 165’s. 

I have a hacman. When the valve is closed, carb function is normal and uses the normal jet. It leans from there, to account for altitude, mostly. And it works.

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Posted

Just got done installing the HACman from Greensky. Had it on the bench for about a year. Anyways, they sent 180 main jets. Haven't run it yet, doing a condition inspection. Maybe run it 2morrow if not to windy.

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Posted

I've drilled out jets for my Jabiru engine.  Need to used numbered drill bits most likely.  You could always work your way up if you need to go bigger.  JImChuk

If you decide to drill it out I suggest you either grind off the old number on the jet or at least document that it has been drilled out. If someone ever tries to work on it down the road they are going to take the number on the jet at face value.

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Posted

I think around 190 is a good place to start for main jets if you are building a HAC system.

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Posted

I had to go to a larger main jet when I designed my in flight adjustable mixture control. One would think that when the valve is closed that jetting would be the exact equivalent of "stock". But something didn't work that way on my system, and others who have duplicated it found the same thing.

I reasoned that the atmospheric pressure reference that I placed inside the air cleaner was carrying sound pulses down the tubes even with the valve shut off, and that those sound pulses were changing pressure in the float bowls enough to require larger main jetting.

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Posted

A jetting chart won’t do me any good here as I have to up size the main jet for with the Hac System installed which these charts do not account for. I think I’m currently running 165’s. 

I have a hacman. When the valve is closed, carb function is normal and uses the normal jet. It leans from there, to account for altitude, mostly. And it works.

 nlappos, correct me if I am wrong but the people I've spoke with say the kit comes with larger main jets than they ran stock. Joey and Chris both have installed larger main jets. 

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Posted

I think around 190 is a good place to start for main jets if you are building a HAC system.

Chris, Joey said the same thing. I guess I'll start with 190's. I think I have 165's now. 

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Posted

I had to go to a larger main jet when I designed my in flight adjustable mixture control. One would think that when the valve is closed that jetting would be the exact equivalent of "stock". But something didn't work that way on my system, and others who have duplicated it found the same thing.

I reasoned that the atmospheric pressure reference that I placed inside the air cleaner was carrying sound pulses down the tubes even with the valve shut off, and that those sound pulses were changing pressure in the float bowls enough to require larger main jetting.

Yes one would think you would stay with standard jetting but obviously other forces are at work. Not sure I want to test the theory but do you think that would change if you installed a one way check valve in-line coming from the air filter? That should eliminate any back flow coming from the filter side when the valve is shut. Just a thought. 

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Posted

The jet size definatly needs to raised up from standard.

If on the test flight the EGT's start to get too high be prepared to ride the choke a little the keep the temps under control.

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Posted

Chris, I have two questions. What did you use for the orifice restriction and where did you source the filling for the carb with the 6M-1 thread?

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Posted

The jet size definatly needs to raised up from standard.

If on the test flight the EGT's start to get too high be prepared to ride the choke a little the keep the temps under control.

Thank you. I will definitely keep that in mind.  

:BC:

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Posted

When I did my hacman it was a total home built effort. Made a distribution manifold (looks nice but was not needed) Made the nipple that threads into the carb to supply vacuum. Quicker and cheaper to make one on a lathe than to order one. Modded a run of the mill brass needle valve to do what I needed (more lathe work) My avid is a C model so opted not to static source from the air cleaner. Felt I was already fighting a problem with lean running at cruise due to the air filter being directly exposed to outside air pressurization. Gave the reference port its own filtered air source underneath the cowl. You will be happy with it once it is all sorted out.   :BC:

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Posted

When I did my hacman it was a total home built effort. Made a distribution manifold (looks nice but was not needed) Made the nipple that threads into the carb to supply vacuum. Quicker and cheaper to make one on a lathe than to order one. Modded a run of the mill brass needle valve to do what I needed (more lathe work) My avid is a C model so opted not to static source from the air cleaner. Felt I was already fighting a problem with lean running at cruise due to the air filter being directly exposed to outside air pressurization. Gave the reference port its own filtered air source underneath the cowl. You will be happy with it once it is all sorted out.   :BC:

Saskavid, how did you make your carb nipple? I’ve been having a hard time finding one. I have a friend who can make anything on a lathe. 

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Posted

I may be wrong but try a 582 vent nipple from the head? It was awhile ago.

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