enginehistory.org

mhamer · Joined: 19 Apr 2013 Posts: 17

I am ready to mount my R-2800 to the frame. I use a Convair 440 engine mount that has 4 bolt holes. The holes are only 1/2in diameter. So I ll use 4
AN 8 bolts from airfasco. They are tested to required tensile of 18500 lb and actual of 23420 lb each. Yield is 14190 required and 22936 actual.
The bolts are alloy steel per AMS 6300C Type 4037 .515” produced per NASM 6812.

The bolts seem quite small for such a heavy engine.. I wonder what anyone here have used as far as mounting bolts. Of course the 2 top ones have the most tinsel stress and those are the ones I worry about

I could drill the mount to fit a an9 but it’s an original mount. I wonder what Convair used...

Thanks

rwahlgren · Joined: 15 Aug 2003 Posts: 324

If some of us gear head types were to build an aircraft it would be too heavy to fly. Yes mounting bolts as well as the whole engine mount seems very light for what it is required do, especially as compared to say a prop shaft. If the holes are 1/2 inch then the attachment bolt or stud would be sized slightly smaller. I don't think you want the threads in the area that passes through the mount though.

Edit to correct spelling

mhamer · Joined: 19 Apr 2013 Posts: 17

Thanks. It’s impressive what a small bolt can handle. Most loads on it will be static, so no hard landing will stress it excessively. Once driven around I will support the motor also from the prop shaft.

wstuddert · Joined: 26 Jan 2015 Posts: 17 Location: Australia

If you look up the NSN number for the part number it should give the tensile strength of the Convair bolts. I have chanced an engine on the airplane, and needed to make a jig to align the Dynafocal mounts with the mount ring, some guide pins helped.

mhamer · Joined: 19 Apr 2013 Posts: 17

Thanks, it’s hung. There was no undo stress on the frame as I drilled the holes using the mount as guide to locate the holes, the bolts slid right in.
Drove around and no cracks anywhere,

Image

wstuddert · Joined: 26 Jan 2015 Posts: 17 Location: Australia

What a nice looking engine, pity to have to run it, but a very nice job.

rwahlgren · Joined: 15 Aug 2003 Posts: 324

That is a nice set up. Though with out fenders those tires could toss some stones and dirt into that engine.

mhamer · Joined: 19 Apr 2013 Posts: 17

I did install fenders now. Those pictures were taken just after I hung the engine. So many little things to do. I have a platform that slides in the frame to work on the top of the engine. Easier than standing on a ladder.

http://www.enginehistory.org/BBimages/teaserbox_7016887.jpg

http://www.enginehistory.org/BBimages/teaserbox_6895526.jpg

jsteele · Joined: 19 Nov 2013 Posts: 11

mhamer,
Man, that's a great looking job!! What version is that, a CB-16? I don't recognize the deflector plate style.

Best, John

mhamer · Joined: 19 Apr 2013 Posts: 17

Hi, Thanks. I can move it around that way. It’s a 99w from Nash Kelvinator
1954.
I polished the deflectors or (coil brackets) they are usually painted black. I still have a lot to do. Setting up relays and a control panel with gauges now.
I have a nice prop that I d hate to cut... I have all the prop tools as well.