[Steve Sampson]

I am starting to work on the baffles and the front of the engine. It raises a couple of questions:

1) Why is the 'normal' route for the c/s oil line from the fitting, just to the right of the two clecos in the attached picture, underneath the engine? It would be much simpler to use a 45 degree fitting and go over the top of the push rod tubes, and then through the rear baffle wall. I doubt it is any longer. Is this ever done? I can find no pictures of it done that way, so am wondering if there is a reason not to. Air trapped in the line? (Apologies, this is a repeat of an question I asked in the engine section to which I have no reply.)

2) The baffle floor on #1 will slope down at about 45 degrees. It seems really steep. I can see nothing unusual about my installation otherwise. Are all the -4 like this? Is it because of the c/s prop? I don't think I cut off much of the cowl at the back.

http://gikonfwf.blogspot.com/2007/12/baffled-by-baffles.html#links

 

[SvingenB]

Maybe it is to prevent (over) cooling of the oil when running and (over) heating when shutting down ? Just a wild guess, but I would imagine the temp below the engine being much more stable than on top of it. What do the manufacturer say about it?

 

[Jaknjoan]

Stainless steel tubing, governor to front oil port

What you need is the stainless steel tube that contours the underside of the cylinders and exits at the front, available from Lycoming parts. Cost is not cheap, like something over $150US,but the sanitary solution is worth every penny.

 

[az_gila]

Flex hose is OK per Lycoming....

What you need is the stainless steel tube that contours the underside of the cylinders and exits at the front, available from Lycoming parts. Cost is not cheap, like something over $150US,but the sanitary solution is worth every penny.

The other option is a Teflon hose with integral firesleeve (to TSO C-53A Type D).

Lycoming's SI 1435 which details CS to FP conversion gives details... but basically it calls for routing away from heat sources, supported to the engine (not airframe) at two locations, and no sharp bends.

If you can meet these requirements, it's even legal for a certified Lycoming.

Do you need a copy of the SI?

gil A

 

[gmcjetpilot]

Its designed that way

1) Why is the 'normal' route for the c/s oil line from the fitting.

The gov is kind of bottom right on the rear accessory case. So if you go over the top you have to run it down, around, over the right mag to the prop governor. Kind of crowded back there. I'm not being flip but it's just the nominal or traditional routing. I would not reinvent the wheel. You have one baffle penetration either way. Also the prefab (ridged) oil lines are made to work down low. There's a nice place to install Adel clamps to support the tube off the sump bolts. I have seen the other way. You're not the first to think of it. Do you really want that hose running over the top? I assume you are going to use a flex hose and not the ridged one? If you use the ridge one than it needs to route down low. #1 is also fwd of #2 so you do have less room.

2) The baffle floor on #1 will slope down at about 45 degrees. It seems really steep.

Well it has to fit the cowl, right. 45 sounds steep but it is what it is. It's kind of art more than set dimensions. You have to fit, cut and work it. You could remake some of the baffle parts and lower the "shelf" of the baffle (so its not so steep) and than just put a wall up against the cylinder fins. Some guys make a nice fillet fairing in front of the cylinder with aluminum. That is #1 which tends to cool OK, so the baffle can physically high up on the cylinder.

Seal Idea - The lower cowl inlet to baffle seals on my RV4 where installed on the cowl lower inlet lip side. The lower seals lap up on top of the baffle. The seals where permanently attached to the cowl. I used thick silicon and they will last for ever. I riveted them on. When I painted the rivets where covered on the cowl. When mounting the lower cowl you might have to flip the seals on top of the baffle as you slide it on, a small effort, but it worked nice and sealed well. Van's set-up I recall just had the lower inlet seal attached to the baffle and just pushed up against the cowl under the flange. It did not seal well. On the RV7 I'm going with round inlets and sealed diffusers (aka ducts). The beauty is forgetting all those floppy seals.

 

[Steve Sampson]

Thanks for the various replies.

Having reviewed SI 1435 I can see no reason not to go over the top. Yes George, 1 baffle penetrtation only, but much easier in the blank face of the rear wall than the narrow little area at the front. Much easier to prevent any chafing. The distance is about the same either way.

It feels more roomy behind the rear wall than in the confined area between the exhausts/sump/starter cable / instrumentation etc. underneath.

I have dropped an e-mail to Aerosport Power. If they say anything interesting I will post again.

PS And yes, AP provided me with a firesleeved hose.

 

[Steve Sampson]

Aerosport Power said "....there is no problem going on the top."