Broken engine mount bolts

[Mrbill]

 I just received my engine today from Scott Casler. When I talked to him about my engine bolt size and torque he just said they were 10 mm and torqued at 20 pounds. I don’t know if that’s exact or not but I think I would just be sure and watch the rubber as your tighting it down.   My main concern is cracking the case. All this said do we have a exact length/sizeFor the bolts?  Dan mentioned earlier grade 5 bolts were recommended.  Is that AN5 bolts?

[scottiniowa]

I just received my engine today from Scott Casler. When I talked to him about my engine bolt size and torque he just said they were 10 mm and torqued at 20 pounds. I don’t know if that’s exact or not but I think I would just be sure and watch the rubber as your tighting it down.   My main concern is cracking the case. All this said do we have a exact length/sizeFor the bolts?  Dan mentioned earlier grade 5 bolts were recommended.  Is that AN5 bolts?

AN5, is an aircraft bolt size
Grade 5 is a bolt strength gage,   with 2 being soft, 5 being grade most used (med) and grade 8, hard.      
 Or as some like to relate:
2- soft and wearing, 
5, pretty darn good for most everything
8,  Darn hard, and when it breaks, that took some doing, but it don't flex much.

Yes, these are just layman terms of strength... you can google all the facts on the grades

[Mrbill]

Update from previous post: After Researching bolt grades I determined that metric bolts grade 8.8 are comparable to grade 5 bolts.  Fortunately Lowes had everything I needed. I did purchase the bushings per plans from ACS. I used two 70 mm length bolts on the bottom and a 80mm and 90 mm on top. All were grade 8.8 M10-1.25. I also purchased 8 10x30mm washers and 4 10mm lock washers and 4 10mm nylon lock nuts. I just tightened up all where they were compressed somewhat.  I’ll update how well this works once I start engine testing.

[Dan_]

Scrounging tip:

Leonard told me a long time ago to go to any airport with an A&P and ask if they have a set of Continental rubber bushings.


He said they will probably have a tool box full of them and may give you a set because they come with the overhaul gasket set and they never change them unless they are visibly faulty.