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Rebuilt carb install

M

MarkCFI

Active Member
I installed a rebuilt MA-4SPA carb on my RV-6. The only thing I’m not 100% certain on is the torque setting on the fuel line connection. Picture below.

I tightened to 40 inch/pounds per a note I read previously. No sealant or picture of any kind. Is that all I have to do? I do not have any leaks and have test run.

Just not sure if there is any type of safety required in the connection. The nut size was 11/16” and I believe that equates to a # 6 B nut.

IMG_0154.jpeg
 
I just tighten fuel connection good and tight with my calibrated wrist. You might take a look at that mixture connection bolt. Looks kind of tipped. My mixture arm needed a bushing to fix the loose hole and it was a rebuilt from Spruce also.
 
Zero4Zulu said:
I just tighten fuel connection good and tight with my calibrated wrist. You might take a look at that mixture connection bolt. Looks kind of tipped. My mixture arm needed a bushing to fix the loose hole and it was a rebuilt from Spruce also.
Click to expand...
Hi Mark, I replaced the Ellison Throttle Body on my RV6 with a MA-4-5 carburetor last year. The mixture arm on the new carb needed this bushing, Van's part number FF-704, to keep the AN3 bolt tight in the hole. Looks like your MA-4SPA might need the same bushing.
 
I’ll get that bushing on order.

I reassembled the same way it was on the previous carb. It looks like it could have used some attention.

One thing I noticed when I took the old carb off was that the nut on the mixture arm was hitting the carb body itself. That may be a symptom of the missing bushing.

Thanks
 
The FF-704 bushing from Vans is $14.70 plus shipping.

Any thoughts on substituting a 5/16” O.D. X 3/16” I.D. Oilite bearing shortened to size? That’s about .85 cents at ACS.
 
MarkCFI said:
The FF-704 bushing from Vans is $14.70 plus shipping.

Any thoughts on substituting a 5/16” O.D. X 3/16” I.D. Oilite bearing shortened to size? That’s about .85 cents at ACS.
Click to expand...
Thirty years ago, I took the mixture arm off my carb and had a machinist friend fabricate a press in bushing for me. It would have worked with a 1/4" bolt but I wanted to use a 3/16" like everyone else.

I am still running the same mixture arm and bushing after 26-years of flying and over 3,500+ hours. I just put a 286-04 $550 carb quick kit in the carb late December / early January and mixture arm bushing still looks perfect.
 
MarkCFI said:
The FF-704 bushing from Vans is $14.70 plus shipping.

Any thoughts on substituting a 5/16” O.D. X 3/16” I.D. Oilite bearing shortened to size? That’s about .85 cents at ACS.
Click to expand...
If the OD is correct (I believe it's actually 1/4") then it will work because all it is doing is acting as a spacer between the AN3 bolt and the bigger hole in the arm. ACS sell brass tubing that is the same diameter as FF-704, available by the foot, for only a couple of dollars. That's what I used, along with the Van's spec for the length of the bushing. I cut it to length by chucking it in the drill press and holding a hacksaw blade while it turned.

FF704.png
 
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Is there a small machine shop around you that could make a bushing for you? Shouldn't take but few minutes. "Let your fingers to the walking in the Yellow Pages". Measure your hole in the arm accurately and make the bushing fit.
 
Excellent info. I think I am going to fab something up based on the diagram. I’ve got a few other adjustments I need to make in the area of re-aligning the mixture cable…. But hope to be flying this weekend.

Thanks for all the responses.
 
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