Bolts for carb air box to marvel schebler O360 carb bolts/studs

[Gary Wallace]

My marvel schebler carb has 1/4-20 threads to connect airbox to carb. There are no studs in carb just threaded holes at this time. Due to clearance issues i dont believe i will get a bolt into carb airbox flange as i only have about 3/8" to get a bolt into the space to bolt airbox to carb. Can anyone help me out with their experience here? I am using aircraft spruce Part # 08-01604 usher airbox, with a Small clearance to get a bolt into between airbox and flange. Likely 3/8 " total length from top of head to end of threads. I expect studs into carb and nuts and washers are the way to go here? But input or source for studs or bolts would be appreciate . Thank . Gary

[zkelley2]

I'm sure there's a way to get that box to work, but I imagine you're using an MA4-5 carb? The heat box that fits that perfect(And doesn't have apparent bushing failures - 2 reviews on spruce complaining of that) is part number 08-01630.
On that box, there is significantly more room to get the bolts in there. I still had to modify that heat box to get the carb heat inlet to work with the bearhawk intake tunnel or whatever you call it, but it looks like the one you have has the same issue. Moved it from the starboard spot it's on to the rear.

If you do use studs and nuts, make sure the nuts are drilled so you can safety wire them.

Alternatively you could probably cut those holes so you can start the screws and then slip it in place, then tighten them down.

I'll take a picture of what mine looks like tomorrow.

[Gary Wallace]

I am aware of bushing failures from the reviews. I will make changes to that at same time as moving carb hea inlet to rear of box. I did think about notching slots into holes of airbox for bolts, but Wasn't too sure about that. Was a quick thought so far. Lo . If you could send me pics i would appreciate i . Thanks again. Gary

[zkelley2]

The airbox that was attached to the engine I bought that came off a Commanche had all 4 holes notched and certainly looked like it was made that way by piper.
Of course sometimes it's amazing what OEM's get away with and the FAA signs off on, so I wouldn't put too much stock in this appeal to authority.

[Bdflies]

I think I’ve 'been there', if I understand correctly. I used bolts. MS20074-04-06 should work. You’re right that there’s no room to insert a long enough bolt if the air box is against the carb. Put a star washer on the bolt shank and tilt it into the hole in the air box. When all 4 bolts are in the flange, put on your gasket and start threading the bolts into the carb, until they pull the air box up.
The air box I used had these holes drilled at an angle, to allow the bolts easy insertion at an angle.
Hope this helps!

Bill

[Gary Wallace]

Thanks all. I will ge it done. I do have the MS20074-04-06 bolts already. I appreciate the quick replies!