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Throttle/Mixture bracket misalignment

Robert M

Robert M

Well Known Member
Has anyone come across this before.......?



I believe I have an alignment problem. What's my best course of action, rotate the oil sump 1 bolt hole? LOL, just kidding.
 
bummer

I think I would plug the existing hole and make a new hole that is aligned with the bracket and carb. you will be able to achieve perfect alignment now. you probably didn't want to hear this.
 
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Shim the engine mount. About 15 washers under the left side should get you there. :D
 
And chance you can slightly bend the right (in the image) leg inboard and rivet a small piece of angle over your firewall hole, the drill through that for your cable?

I'm not sure if that'll throw your alignment out for your carb though, I used a Rotec TBI on mine and had to make my own bracket anyway.
 
Contact Van's. It is possible the bracket is miss-punched.

If not, Van's can punch you one without the holes. Then you will have to drill them yourself. (I had to do this with the MA3 I installed on my O-290-D2 and they were very accommodating.)
 
On my engine and another one I helped install, the Van's bracket was only a starting point. I made substantial modifications to both to get the cable geometry right.
 
Thanks to all.

RVDan - LOL, yes, I had thought about shimming with several washers but figured the VS offset would also have to be changed - too much modification for me. Plus, longer bolts would have to be purchased - I'm too cheap.

Steve - I looked at that as well. Unfortunately the Facet fuel pump is directly in the way if I re-drill. Moving the pump would require re-plumbing the fuel lines. Then there's the wiring that runs up that side of the firewall.

Kyle Boatright - If there is no other solution, I thought a simple mod of cutting the top part of the bracket about half way back, bend the bracket to align with existing holes then rivet a small plate (of the same thickness steel) to hold it all together. The holes are very close to being inline vertically, they just need to move over horizontally.

KRviator - Very good idea. If Van's has no other solution, I will look at all possible ways to reconfigure this bracket/cable alignment issue. Its not out by much so it won't take that much.

N941WR - I am calling Van's today and see what they say.
 
Kyle Boatright said:
On my engine and another one I helped install, the Van's bracket was only a starting point. I made substantial modifications to both to get the cable geometry right.
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On the prepunched kits the instructions tell you exactly where to drill the holes and the bracket should line up with them. So, either Robert drilled the holes in the wrong place or Van's did. Either way, the cleanest fix is to get a new bracket.

Here is a picture of the stock bracket, on the right, and one punched without the carb holes, on the left.

The MA3 carb has a different hole patter (smaller) than the MA4 carb does.

Here is a picture of the modified bracket, before powder coating. The odd looking hole adjacent the carb opening was required to provide clearance for the throttle arm.

The above is why I recommend Robert order a new bracket.
 
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All righty then.

I spoke to Ken at Van's. He said that the A2B engine has a more aft placed carburetor mount than the Lycoming engines that are used today, (he specifically mentioned the D1A). He recommended a modification.

What I'm thinking now is to take the bracket I have and cut it into two parts. Attach the cables to the aft part of the bracket and to the carburetor. Then take the forward part, line it up to the carb mount and rivet the two pieces together.

The other option would be to replace my sump with one from a D1A, probably gonna go with the mod.

Thanks for the help guyz, you are the greatest!
 
Why would you cut and paste a carb cable bracket? This is not a place to monkey around. Be a builder...make careful templates until you have defined the desired shape, then cut and bend a complete new one-piece bracket.

I spoke to Ken at Van's. He said that the A2B engine has a more aft placed carburetor mount than the Lycoming engines that are used today
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Another good reason to make a new bracket. In the above photo, the cable sheath end of the bracket appears to be much too close to the firewall. There needs to be a fair length of cable between firewall and bracket so the engine can shake without fatiguing the bracket.
 
Just take some thin aluminum and cut/bend/mangle to make it fit - then duplicate that piece in steel and you'll be set. I had to do that with both my throttle and mixture brackets, the final product is cut from leftover 6" C-purlin from a barn.

I initially tried the Van's bracket also - held it up in position and said "Hmmm, nope...", then rotated and twisted it around, each time with a "Nope, not that either" and "Huh-Uh, no way" until finally giving it a good fling across the barn into the scrap metal pile and I fabbed one up that did what I wanted it to do.
 
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Here's what I did and I'm still not happy. The mounting hole for the mixture cable is still in the wrong place and that would require more surgery on the bracket. What I need is more space between firewall and cable attach points on the bracket, but that ain't happenin'.

So, I am going to order a new one from Van's, align it correctly and drill the four carb bolt holes and the intake hole. If I am not happy with those results, I will fabricate a whole new piece that best suits my needs. I will use the "Frankenbracket" (in the pics) to surgically come up with a workable template, then fabricate a clone.

Still a work in progress.....





On a side note, this Frankenbracket is quite sturdy and would probably work just fine.
 
Robert M said:
Here's what I did and I'm still not happy. The mounting hole for the mixture cable is still in the wrong place and that would require more surgery on the bracket. What I need is more space between firewall and cable attach points on the bracket, but that ain't happenin'.

So, I am going to order a new one from Van's, align it correctly and drill the four carb bolt holes and the intake hole. If I am not happy with those results, I will fabricate a whole new piece that best suits my needs. I will use the "Frankenbracket" (in the pics) to surgically come up with a workable template, then fabricate a clone.

Still a work in progress.....
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You're not married to the carb bolt holes for attaching the bracket - if you can make a simpler or more convenient bracket that attaches to another convenient hard point, that works too.
 
If you go with the Frankenbracket, people will shake their heads and whisper behind their hands...;)
 
If you go with the Frankenbracket, I'll tell your mom!

Robert, if you have to chop up the replacement bracket, I can weld it up for you.
 
N941WR said:
If you go with the Frankenbracket, I'll tell your mom!

Robert, if you have to chop up the replacement bracket, I can weld it up for you.
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Thanks Bill, but "I know a guy" that is a welder that lives only a few minutes from me. He, too, is building a plane - a Wittman Buttercup.

rightrudder said:
If you go with the Frankenbracket, I'd use solid rivets instead. The bracket is subject to a lot of vibration.
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You betcha. These pop rivets are for "fitting" only.
 
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