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  #1  
Old 02-24-2017, 08:10 PM
8 Builder 8 Builder is offline
 
Join Date: Aug 2014
Location: Lowell, MA
Posts: 41
Default Engine Offset

I am getting ready to start fitting my upper cowl. I made lines at the centerline of the cowl and the centerline on the boot cowl for alignment to each other. While I was standing at the front of the engine and looking aft I noticed something.
Imagine looking aft and sighting down the upper joint of the engine case halves like the barrel of a gun. When I did this, the sight line was about one and one eighths inches off to the right of a vertical line I had drawn down the middle of the firewall. I realize that the engine is mounted to pull a little toward the right; but THAT much? Curious as to your findings. I believe my Lord mounts are all seated in the engine mount correctly. Also what effect does the offset have on the cowl; especially at the spinner/cowl gap.
Thanks, Rich
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  #2  
Old 02-24-2017, 08:27 PM
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RV6_flyer RV6_flyer is offline
 
Join Date: Jan 2005
Location: Uniontown, PA
Posts: 2,536
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I know the RV-4 and RV-6(A) both have an offset to the engine. (Offset from centerline of the fuselage.) Yes it is noticeable but it has been over 20-years since I was working on the cowl of my RV-6 and do not remember. They say the mind is the 2nd thing to go and I cannot remember the 1st.
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  #3  
Old 02-24-2017, 08:56 PM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 3,657
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Quote:
Originally Posted by 8 Builder View Post
I am getting ready to start fitting my upper cowl. I made lines at the centerline of the cowl and the centerline on the boot cowl for alignment to each other. While I was standing at the front of the engine and looking aft I noticed something.
Imagine looking aft and sighting down the upper joint of the engine case halves like the barrel of a gun. When I did this, the sight line was about one and one eighths inches off to the right of a vertical line I had drawn down the middle of the firewall. I realize that the engine is mounted to pull a little toward the right; but THAT much? Curious as to your findings. I believe my Lord mounts are all seated in the engine mount correctly. Also what effect does the offset have on the cowl; especially at the spinner/cowl gap.
Thanks, Rich
I did not measure my 7 but I think the engine rotation is such that the centerline of the crank passes through the center of the cowl. One side is longer than the other on the SJ.
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  #4  
Old 02-24-2017, 09:22 PM
rv7charlie rv7charlie is offline
 
Join Date: May 2006
Location: Pocahontas MS
Posts: 1,857
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Try measuring the motor mount at the dynafocal rings, referenced to the firewall and distance from the fuselage sides. IIRC, when I was modding my mount for my alt engine, Van's told me that the offset is at the rear of the engine and the crank flange is on the centerline of the fuselage, but angled to the right.

Charlie
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  #5  
Old 02-24-2017, 09:33 PM
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skylor skylor is offline
 
Join Date: Aug 2009
Location: Southern California
Posts: 536
Default Offset

I'm not sure of the exact amount of offset on the -8, but it's designed so that the the aft edge of the spinner is essentially on the centerline of the fuselage but the aft end of the engine is shifted significantly towards the left side. The front of the cowl has a noticeable angle on both the inlets as well as the spinner disk. On my IO-360 angle valve, there is very little clearance between the cylinder 4 valve cover and the cowl, and a significant amount of clearance on Cylinder 3.

Skylor
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  #6  
Old 02-25-2017, 08:29 PM
8 Builder 8 Builder is offline
 
Join Date: Aug 2014
Location: Lowell, MA
Posts: 41
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Thanks for the answers everyone. Looks like it is the way it is supposed to be. Upper cowl on for measuring today and cut out and installed the oil door. Made my own invisible hinge. Used a Hartwell latch for closure.
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