Engine case final torque

jdeas · #1 12-19-2013, 08:58 AM

Reading the rebuild manual it appears the 1/4" bolts around the edge of the case halves should be torqued to 75 in/lbs in a pattern when joining.

Standard torque is ~95 in/lbs unless otherwise listed in the manual and while most special torques are listed in the rebuild manual I can't find this one. Can someone clarify if these bolts stay at 75 inch/lbs or get increased to standard torque value?

Thanks for the correction Mike!

Mike S · #2 12-19-2013, 09:00 AM

Are you sure that is FT/lbs and not IN/lbs???

cajunwings · #3 12-19-2013, 09:08 AM

Just finished my IO-320 build. No where in the O/H manual are there any references to torquing these 1/4" bolts to more than 75 in/lbs. Inch Pounds, definitely NOT foot pounds!

Don B
RV 9 engine build done

rocketbob · #4 12-19-2013, 09:22 AM

I just did a lot of work on an engine that had all 1/4-20 bolts torqued to the 75in/lb spec. It leaked all over the place. I go 100. At least.

Bavafa · #5 12-19-2013, 09:36 AM

I don?t mean to hijack this post, but anyone know what is the torque setting of the nut that holds the gear on Slick Mag. This is the 9/16 castle nut on the shaft.

DanBaier · #6 12-19-2013, 10:09 AM

I think the specs are 75 inch pounds for the bolts that get safety wired in the sump and 96 inch pounds for the rest of the bolts around the perimeter. My source is the service instruction for the sump bolt installation and the table of limits for the other.

Dan

jdeas · #7 12-19-2013, 10:35 AM

Quote:

Originally Posted by DanBaier

I think the specs are 75 inch pounds for the bolts that get safety wired in the sump and 96 inch pounds for the rest of the bolts around the perimeter. My source is the service instruction for the sump bolt installation and the table of limits for the other.

Dan

That is the question, Does the table of limits define the final torque given they are called out as 75 in the assembly sequence?

mahlon_r · #8 12-19-2013, 10:42 AM

I always torque them to 96 inch pounds and have done so more times then I care to comment about. As one poster stated, they will likely leak at less torque.
Merry Christmas,
Mahlon

jrs14855 · #9 12-19-2013, 03:18 PM

If the current parts are used the bolts that are safetied use shear nuts. These bolts do not seal anything unlike the rest of the case bolts.

Kyle Boatright · #10 12-20-2013, 08:15 PM

This is interesting and timely thread. I meant to post about this yesterday.

My engine has been a bit of a leaker from day 1. Nothing major, but it probably uses a quart every 8-10 hours, with a good portion of that ending up on the airplane's belly.

Recently, the quantity of oil on the belly has seemed to increase. So a few weeks ago (time flies when your wife is under the weather, and you have a job and a 3 year old), I pulled the cowl and baffles to search for and hopefully eliminate as many leaks as possible. Also, I wanted to give the engine a good visual inspection since it has been 13 years since the baffles have been off.

I'd noticed a fair amount of oil seeming to come from the area of the case seam just in front of the oil pan. Addressing that was the last item on my list of items to visually inspect and verify torque.

So yesterday, at almost exactly the same time this thread was started, I was checking the torque on those 3 or 4 fasteners. What did I find? The single bolt that is threaded into the opposite case half (adjacent to the starter) was loose. Very loose, as in not even snugged down. So I snugged it down, torqued it, and have my fingers crossed that my engine will be a little tighter and drier in the future.