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Engine mount “bullet”

Sam Staton

Well Known Member
I am at the engine mount stage, and have heard “bullets” discussed in the past. They work as locators for the bolts and fall out as the bolts are forced into position. My question is this - where do I get these magical devices? Thanks in advance for all leads.

Sam
 
The aviation dept of Lowes, HD, Ace, etc.

Assuming I'm understanding your intent, bullets or custom drifts are commonly just male fasteners with a long tapers machined and/or ground and/or appropriately polished onto them You can use most any bolt but why incur more costs than necessary?

Edit = pix added. Bolts from local Ace HW. Without making custom drifts, I’d still be trying to install the wings for the first time.
 

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Bullets

Not much room on a Lycoming for a long bullet to "fall thru". I have a long bullet with a T handle welded on and a relatively short one that will "fall thru".
IIRC the Lycoming bolts are AN7. You won't find that size in most hardware stores.
 
Mounts

I use undrilled bolts as do many certified airplane. All metal lock nut. I do the bottom mounts first. Install the first bolt and nut and tighten. Then the other lower bolt. Then the upper bolts. Using that sequence you can use a hoist to move the engine a bit for the upper bolts. Be gentle with the hoist and the lifting hook on the Lycoming.
 
Drift pin

Drift pins are very useful. I only needed one for the engine.
Installed both top mounts and bolts first. Snug but not fully tightened.
Slip a bottom assembly into place with a drift pin. Release just enough off the lift to make contact and hold parts in place. Slide out the drift pin and insert the bolt. Repeat on the remaining bottom mount. Maybe 30 minutes.
 
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I've mounted two whole engines. Took a half hour or so each.

Drift pins (bolts with a taper ground on the threads) and appropriately sized Phillips head screwdrivers helped. Top mounts first, then gravity is your friend and compresses the bottom mounts so the holes align.
 
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