Carb Heat Box

[Steve Pierce]

The studs in the oil sump that hold the carburetor to the sump?

[Subsonic]

No, I'm referring to studs on the carb to heat box interface. Mine came with bolts there.

[Steve Pierce]

No, I'm referring to studs on the carb to heat box interface. Mine came with bolts there.

Should be AN74A3 drilled head, course thread bolts 1/4" bolts. Called out in drawing engine install drawing 14474.

[Subsonic]

Thanks Steve. That is what I have now. They were safety wired. An earlier post in this string suggested the 0-320 A1A should have studs. That's the engine I have. Another item: I just received my Preferred Parts 11303-000 heat box in the mail and it appears to be a new-old stock item for PA-18. It is a very well made part and construction appears to be of same quality as my original heat box that is being rebuilt by the Heat Box Doc right now. I see excellent brazing and the original type hollow shaft with detents on the arm spring and a brazed on flapper, etc. It's different from my PA-22 heat box in that it has the approx 30 degree bent-back-facing side heat tube, a shorter neck at the carb interface, and does not have the cross plane diffuser/atomizer in the neck. It also has two holes in the top just behind where the filter mounts. Don't know what those were for... It's so much better made than the C-150 ChiCom made item I returned to Spruce. Very nice. Anyway, I'm wondering if this box can be substituted - as is - on my Tri-Pacer. Will engine performance change with the shorter intake tract length?

[Steve Pierce]

Thanks Steve. That is what I have now. They were safety wired. An earlier post in this string suggested the 0-320 A1A should have studs. That's the engine I have. Another item: I just received my Preferred Parts 11303-000 heat box in the mail and it appears to be a new-old stock item for PA-18. It is a very well made part and construction appears to be of same quality as my original heat box that is being rebuilt by the Heat Box Doc right now. I see excellent brazing and the original type hollow shaft with detents on the arm spring and a brazed on flapper, etc. It's different from my PA-22 heat box in that it has the approx 30 degree bent-back-facing side heat tube, a shorter neck at the carb interface, and does not have the cross plane diffuser/atomizer in the neck. It also has two holes in the top just behind where the filter mounts. Don't know what those were for... It's so much better made than the C-150 ChiCom made item I returned to Spruce. Very nice. Anyway, I'm wondering if this box can be substituted - as is - on my Tri-Pacer. Will engine performance change with the shorter intake tract length?

Did you read page 2 of this thread? Some of the boxes used spacers to get the height correct from the factory. The clearance would be the issue with me. If it worked I would do it as a substitution of parts since you can't get what is called out in the parts manual.

[cozzmo81]

I used the box from preferred Airparts as well. I was very happy with its quality as well.


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[Subsonic]

Next issue. There is a special pin and bushing that attaches the heat box lever to the cable that goes to the panel. My bushing is broken and the stud, or pin which is threaded on one end and has a hole in each end, (One hole is for the castle nut cotter pin, the other hole is for the push-pull cable) is cut half through. I don’t know the part numbers for those or where to find them. Any help appreciated. Thanks, Subsonic

[cozzmo81]

I think this is what you are talking about.

https://www.univair.com/piper/piper-...ng-cabin-heat/


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[Subsonic]

That is it! Happy New Year!

[Steve Pierce]

It is called out in the illustrated parts manual and in the engine installation drawing on the Short Wing Piper Club drawing CD. They call out the stud and the swivel separately.