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Engine Nuts

B

Brambo

Well Known Member
I was somewhat surprised to see Van's instructions for hanging the engine saying that because it's impossible to get a torque wrench on the nuts, and torquing the bolts is "unreliable", that we should torque the engine mounting nuts by "feel". The book says torque should be 450-500 inch/pounds. I can't say that I have any idea what the "feel" of 450-500 inch/pounds is.

It seems to me that torquing the bolt, while not completely accurate, would be a whole lot closer to correct than anything I could "feel". Just wondering what others thought and did.

It seems strange that four of the most important bolts in the airplane can't be properly torqued. You would think that someone would have come up with a special tool, or better yet, that the engine manufacturers would designed the engine to allow proper torquing.

Bill Rambo
RV-7A
 
Yep, I thought the same. I measured the drag torque (run-on Q) and added that that to the indicated touque. I made a "special tool" which consited of a 5/8 inch box end wrench welded to a 1/2 in to 1/2 in drive adapter (or maybe it was a 1 inch extension). I used this to access the bolt heads. Head torque is more accurate than German torque.

The nuts required modification of yet another 5/8 inch box end wrench. It needed to be ground down on the top/bottom to lower the profile so it would slide past the tappet tube on the #4 jug.

IO-360, parallel valve, Dyna focal 1 mount.

Jekyll
 
When I don't have good access to torque a bolt / nut I put the same size bolt head in a vice, set the torque wrench, and try to mimic the angle/ length of wrench handle to get a "feel" for what that torque value is when the torque wrench clicks. You would be surprised how close you can then come by torquing the subject bolt / nut by hand.
 
Last edited:
When installing the engine mount bolts, you are tightening down to a sleeve inside the cushion mounts. The feel of the wrench is pretty obvious when you hit this sleeve. Therefore exact torque is not nearly as important as it may seem.
 
Mel said:
When installing the engine mount bolts, you are tightening down to a sleeve inside the cushion mounts. The feel of the wrench is pretty obvious when you hit this sleeve. Therefore exact torque is not nearly as important as it may seem.
Click to expand...

Right...I just did this and you feel a definite increase in torque required to continue to turn the nut. Once it bottoms out on the sleeve, it won't go much more at all...at that point, line it up for the cotter pins and you're good.
 
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