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Old 12-09-2022, 07:30 PM
Nashpdman Nashpdman is offline
Join Date: Sep 2020
Location: Nashville
Posts: 69

Building a IO-540-J4A5 for my RV10, which was turbo charged in its former life, with factory oil squirters. Like previous comments, I'm hoping the oil squirters will pull heat out of the pistons so I can run pump gas.
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Old 12-09-2022, 08:14 PM
Greg M Greg M is offline
Join Date: Jan 2020
Location: Salem, Virginia
Posts: 9
Default Piston cooling nozzle assembly

For those of you who want to see proof that you have piston squirters in your IO-390, check out Lycoming's IO-390-A Series Engine Illustrated Parts Catalog. Item 16 is "NOZZLE ASSEMBLY, Piston cooling" which is in all models of IO-390A engines.
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Greg Morton
Roanoke, Virginia
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Old 12-10-2022, 08:18 AM
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Fred.Stucklen Fred.Stucklen is offline
Join Date: Oct 2006
Location: Brooksville, FL
Posts: 465
Default viscosity valve trick

Originally Posted by Toobuilder View Post
Yep. I went bigger too. That was before I tried the viscosity valve trick, but needless to say I have ample oil cooling now.
So what is the viscosity valve trick? I've never heard of it.....
Fred Stucklen
RV-7A N924RV Flying (2090 Hrs & counting)
RV-6A N926RV 875 Hrs (Sold)
RV-6A N925RV 2008 Hrs (Sold)
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Old 12-10-2022, 10:42 AM
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Toobuilder Toobuilder is offline
Join Date: Jul 2009
Location: Mojave
Posts: 5,096

The old school method for dealing with coagulated oil in the cooler and the resultant oil pressure rise was a spring loaded piston in the accessory case. In normal ops, the oil flow goes 100% to the cooler, but in the case of a restriction, the piston will lift and bypass the cooler. The current vernatherm has this feature as well, but experience indicates the sealing capability of the cone seat is wildly variable and as a result, some engines do not see the cooling oil flow they need. The viscosity valve is VERY effective and can completely transform the oil cooling capability of a given engine. This valve is discussed at length in the threads dealing with a "ball valve" for controling oil flow in winter ops. A search should bring up many examples.
WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
Harmon Rocket II -SDS EFI
1940 Taylorcraft BL-65
1984 L39C - SOLD
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