saskavid

So how exactly are the crankcases vented on these engines? If you aren't vented properly or freely or have a pvc valve type  issue that is rpm dependent or related and build up crankcase pressure that could make for a crap idle situation maybe... this is a long shot but you have been chasing carb issues and everything seems to be checking out...

Possibly a fuel pump pulse line collapse temperature related.  or maybe the pump pulse diaphragm has a crack in it creating an intermittent leak? 

I think when you reply to the thread there will be a paper clip thing that says drag or choose files. if you hit the choose files it will prompt your computer and you then can attach the video that way or if it is a video already on utube there is the insert other media at the bottom to stick that on here. 

https://www.aircraftspruce.ca/catalog/appages/vortelator_kit_certified.php
 
Hey Paul this is something that may be of interest to you. Thought about how this might work on the tops of the flaperons to keep the boundary layer attached. People have also been toying around with the idea of putting vortex generators on the underside of the wing. Don't know if anyone has. I would think putting them right on the underside of the spar between the tip and lift strut could get the boundary layer sticking better out there in that somewhat over twisted portion of the wing area. 
All that vortelator is, is thick vinyl that has been pinked with a somewhat courser than scissor pattern. I did buy some but never did anything with it so far.

So is there actually still an avid flyer yahoo group? Google search for me shows nothing....

Just a thought... you did purge the rotary valve chamber at the bleed screw located above the water pump? some people haven't because they didn't know about it and trashed their engine and plane in that order because of it.

I'll guess it is out of a one of those bubble canopy bell helicopters....

Well I will add my ....expertise... to everyone else's that has posted here. It effectively becomes about the horizontal distance between the attachment points of the airframe and the engine and the leverage that can then be generated at/near the weld points to create points of force that effectively exceed the strength of the steel and lead to points of cracking that become lines of cracking and everything then goes for shit and breaks eventually. 

With Dean's design history(ellipse, bellanca eagle, explorer and others) I don't think he goofed  anything when he designed the stol airfoil. It was initially a very light plane design with not a lot of horse power to start and not carrying a lot of inertia over the fence so to speak so he did some things to compensate for the unexpected and unfamiliar. You see and hear of some pretty scary sustained  angle of climb demonstrations at reduced air speeds by pilots who know the plane and what it can do. I am not one of them. Like leni said the design was simple so as to get would be builders into the air successfully. In many cases improving upon the design involves taking what was once simple and creating complexity that can make success of completion a nonevent. 
I learned sme time ago that anything mechanical designed to do something and work is only ever going to be conceived as an amalgamation of compromises. Many considerations made Dean Wilson make the design the way he did. 
 

should work now

http://www.avidfoxflyers.com/applications/core/interface/file/attachment.php?id=4206
This old june 1996 news letter has some general overview into the airfoils Dean Wilson did on the avid and why he did the undercamber the way he did on the stol version. 

The best advise I can give you and the best advise you are going to get , is if you are going to do your own thing is to do your homework regarding the physics of braking systems. Otherwise you will invariably be floundering in why shit isn't working when you think it should. At the time I started it was about 2002 and my learning curve began to show me most of what I was seeing at that time was a lot of mythology and folklore in online discussions. back then  the first thing I saw  done on an avid that was effectively concrete was done by a guy named larry martin. What made it concrete was that he talked to george happ of matco and was told what to do and what leverage it would produce. If you want to know what it was larry did just look at what Nick or nlappos has illustrated and done to his avid setup posted and pictured in various places on this forum. At the time that larry did his work the only noteworthy that transpired was someone taking it upon themselves personally to email contact him to inform him his methodology for determining leverage was wrong....beyond that no one really seemed to care at the time. 
I followed larry's lead with my own work, going  marginally shorter with my master cylinders and developing a retrofit brake pedal to get some required structural revisions for line psi development. Joey/c5engineer did a thread  called gocart to matco brakes on this forum utilizing my revamped brake pedal design. If you see an avid with brake pedals like what are featured in that thread they are on the plane because I built them.Easy to install, pain in the butt to design and then build. You will see a few avids out there utilizing and flying with that design. With novice pilots and within certain conditions you have to be aware of how powerful the brakes can be.
For the avid, other designs like the parrellogram or the latest fad of indirect linkage design can work and firstly be made to look good and workable on paper. the reality of math on paper is that it is always going to be accurate but in practice of application will typically be shown to be incomplete especially where any condition of leverage is involved. 
 

They use the 1/8th inch lines over the 1/4 because the scale and ratio implies a gain in rigidity, less ballooning. In a conventional avid doesn't make or break the deal because it's difference as a function of percentage between the 2 isn't where force is gained or lost to an extent that it matters. I can wrap a 600 psi gauge with my planes setup and a 1/4 inch line. that is the limiting psi you need. Any more does nothing more to stop the plane. My personal preference for the lines to the mc's from the res would be 1/4 inch to facilitate more of a funnel effect getting fluid pressure to the calipers when everything is static.

Well it looks to me like you don't have any fluid in the left master cylinder lines.Just from pictures hard to tell. The trick to making leverage is to get the activation shaft of the master cylinder as close to the brake pedal pivot point as you can. And by pivot point I mean the place where the brake pedal bolts to the rudder bar. leverage works as a function of perpendicular distance to the master cylinder centerline  of that brake pedal attachment point/ pivot point. On a non magnum avids with mc4 master cylinders all start with 5.3 to 1 leverage regardless of the length, assuming that they start with the activation shaft of the mc touching the back of the rudder pedal. The exception being the ultra short mc4g and such which have like 4.7, because the clevis contacts the rudder pedal not the shaft . With activation or when you step on pedal the longer the mc the more the leverage is reduced from that starting value. the original owner builder was probably modding on the pedals already somewhat but without a comparative picture hard to tell.

If you really want to break down the full physics of light aircraft, the best landing that can be done is one that produces optimum insurance of sustaining structural integrity within the conditions the plane is being landed in. In other words the softer the better no matter how tough you think something is. The sky cowboys have done some interesting work but the question still remains how much or how many of these style of landings can the collective structure of the airframe take before some unforseen event becomes an expensive repair bill?....at best or maybe worse? The best answer becomes this is what they can do... not what you should do with them... the good landing is the one you can always walk away from, the best landing is always the one that will keep you walking back to a fully intact airplane. 

If my memory is accurate the throttle cable adjuster fitting has the same threads as the nipple requires. I would have used the jam nut as a dimensional gauge to cut the threads to the proper depth on the fitting I made. Also put a ball valve plumbed into the system so I could have a secondary venting source separate from the restriction orifice. It was a piece of mind redundancy at the time I put it all together. Might be useful in an inflight jam. Also help to gravity feed fuel into the carbs quicker when the plane is not running or just getting running. 

I just took out the screw where the nipple will go and measured the thread pitch with a metric pitch gauge. My lathe will cut metric threads. the coolant bypass nipple may be the required thread pitch as well. just made the nipple end to the same look and dimensions as the vent nipples for the carb float chamber.

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.   

Old stuff is probably something like aviation form a gasket. Permatex is the one that comes to mind off hand. Brown and tacky still that is probably what it is. Once you smell it you never forget it....

According to the drawings I have looked at that heim joint assembly is in upside down to boot. My guess is the same as Nlappos. Binding between the heim and the f1 frame created a side load in the root of the threads concentrated at the jam nut and thru a number of cycles eventually led to failure

The first f-7a bellcranks weren't available until about july of 1996. That is when John Larsen finished his development work and they went into production. 

The tubing is 4130 the lathe machined steel is 1018 cold rolled. The bushings are aluminum. 

From a appearance stand point this is a well executed repair from what I can see of it. If it looks good chances are it is good. As long as the aluminum is properly conditioned prior to gluing it all together should never bother again. How thick was the aluminum you used to build this reinforcement? 

Here are some pics  of pedals in my plane and on a test stand. You will see a few avids flying and using this design. Effective and easy to install but not easy to build .