Engine Mount Holes on engine case

[CHARLES DEBOER]

Just curious....WHERE does the threaded part of your bolts end/start? IF you are going to have a bolt fail, it will most likely fail in the threaded part...
I would swap those bolts out for AN bolts and have the threaded part as close to the nut as possible....

The bottom holes might need to be re-threaded with a Heli-coil to close up the gap. THAT's why I used studs on the bottom and put the nuts inside the cabin for those two and safety wired them. I double-nutted the top two. I also removed that steel insert on the right top engine mount hole...

Bob

BOB, THANKS I DIDN'T THINK ABOUT THE THREADED PORTION INSIDE THE BUBBER SHOCK MOUNTS.   WHAT IF I PURCHASED A LONGER BOLT AND CUT OFF THE THREADS TO MAKE THE BOLT SHORTER W/LONGER SHAFT and leave enough threads to screw into the block?  THAT WAY I WOULDN'T HAVE TO INSTALL HELI-COILS.  I HAVE NEVER DONE HELI-COILS.
I HAVE ABOUT 1  1/2" OF SHAFT ON A 2  3/4" LONG BOLT,  AND  1 3/4" OF SHAFT ON A 3" BOLT.  SINCE THE TWO RUBBER SHOCK MOUNTS AND TWO LARGE AREA WASHERS ARE A TOTAL OF 2" LONG,  I WOULD NEED A 3 1/8" LONG BOLT AND CUT OFF 1/2" OF THREAD TO AVOID INSTALLING HELI-COILS.

[Steve]

I tried to buy grade #5, 10 mm, 2 3/4 inch bolts at NAPA but they only carried grade #8.  I'll have to find another source. Here are some pictures using the wrong bolts.

Looking at that camshaft plug in the case, it appears that it might be an after-market plug that isn't squeezed into grooves provided in case half's... I had a bad experience with the after-market plug (it popped out after a few hours - my speculation is oil sloshing going on back there that doesn't happen when the cam is present)... I rebuilt the engine with the stock cam plug and other builds with a cover similar to the crankshaft cover...

FWIW: I have been told that a metric 5 is the equivalent strength of an (AN) grade 8 - wondering if there is confusion about that somehow?...

[CHARLES DEBOER]

I'LL HAVE TO CHECK WITH SCOTT CASLER ON THE CAM PLUG.  I HAVE NO ENGING BUILDING EXPERIENCE.  I HAVEN'T HEARD OF ANY BAD REPORTS ABOUT CASLER ENGINES.
THANKS FOR THE INFO. ON THE grade #8 "AN" vs. METRIC grade #5, 10mm BOLTS.

[Bob S.]

Cutting the bolts are OK...


I wouldn't worry about the cam plug if built by Scott!!

[Leonard]

Hi
 in the hole on top where the insert is use a mm bolt and the other side I use a 3/8" bolt with a metal lock nut I use metal lock nuts in the engine area.  Am mounting the engine on my Cabin Eagle now and an having to round up metal locknuts. Leonard

[CHARLES DEBOER]

I just stripped out both engine mount holes on the bottom of my engine block.  The longeron on the aft portion of the fuselage was level and station #1 was perpendicular and square to the longeron and aligned with the engine block and mounting holes.  But, the bolts were compressed into the mounting spools  by the rubber grommets, which didn't allow me to turn the bolts by hand freely.  So, I used a wrench to turn them very lightly until they grabbed a couple of threads.  They did. At the wrong angle.

Anybody have pointers on how best to install helicoils?  Never done it before.  Should I get them from ACS or my local auto supply??

[rockiedog2]

I just stripped out both engine mount holes on the bottom of my engine block. 

how deep did you go with the bolt?

[CHARLES DEBOER]

I carefully ran a tap 3/4 inch into each hole, then cut each bolt to 2 3/4" to make sure they would't bottom out.  But, the bolts only turned in about three or four threads.
Is there a tightening pattern that would keep me from drawing up one side more than the other, thus causing the bolts to enter the block at an incorrect angle?

[Steve]

I carefully ran a tap 3/4 inch into each hole, then cut each bolt to 2 3/4" to make sure they would't bottom out.  But, the bolts only turned in about three or four threads.
Is there a tightening pattern that would keep me from drawing up one side more than the other, thus causing the bolts to enter the block at an incorrect angle?

Strikes me there is a mismatch between the tap thread & bolt... Drill & tap some scrap material to figure it out... Remember - those are metric holes in the case... Discuss your findings with Leonard - you need a pro opinion on this...

[Bob S.]

I bought a heli-coil kit from my local auto-parts house and the tap supplied followed the threads in the case quite well with no special tools or alignment... one MUST TRY to be as square as possible at any rate... Follow the instructions on the Heli-Coil Kit....

[CHARLES DEBOER]

I carefully ran a tap 3/4 inch into each hole, then cut each bolt to 2 3/4" to make sure they would't bottom out.  But, the bolts only turned in about three or four threads.
Is there a tightening pattern that would keep me from drawing up one side more than the other, thus causing the bolts to enter the block at an incorrect angle?

Strikes me there is a mismatch between the tap thread & bolt... Drill & tap some scrap material to figure it out... Remember - those are metric holes in the case... Discuss your findings with Leonard - you need a pro opinion on this...

I tapped out each hole in the block with a metric course thread tap before trying to install the engine to make sure I had 3/4" depth and screwed a bolt into each hole.  Just a dumb operator error!  I think the problem was compressing the rubber mounts onto the bolt using a nut which made it difficult to turn the bolt by hand thus not being able to feel whether the threads were engaged properly.  Plus not paying attention to the angle of the block as I was drawing it in as I thighened the bolts.

[CHARLES DEBOER]

I bought a heli-coil kit from my local auto-parts house and the tap supplied followed the threads in the case quite well with no special tools or alignment... one MUST TRY to be as square as possible at any rate... Follow the instructions on the Heli-Coil Kit....

How did you make sure the new holes were perpendicular to the block?

[Bob S.]

I have a steel block with a hole bored in it that is perpendicular that I drill thru when tapping free hand.... I usually clamp it to my work before hand... It's too big usually, for tapping so I just try and keep the tap centered by aligning on the outside/square sides...

[Bob S.]

I did the exact same thing trying to screw my bolts in the bottom two holes.....that's why I had to Heli-Coil them... then I went to studs in the bottom two mount holes!

[CHARLES DEBOER]

I did the exact same thing trying to screw my bolts in the bottom two holes.....that's why I had to Heli-Coil them... then I went to studs in the bottom two mount holes!

Where did you get the studs?