Baffling Question

A Baffling Question...ha ha!!

I am starting on the firewall forward section of an Experimental Bearhawk Patrol. This is my first build, and am unsure what an industry standard is for securing baffles to the engine case when the two don't match. Over all the sheet metal, hardware, and instructions are real good! But baffle attach points are different on my case. (My engine is a Lycoming parallel valve IO-360 with a narrow deck case.)

I thought I'd show some photos of my thoughts and seek some feedback.

The big Picture looks like this so far. I like the fit I have around #4 cylinder valve cover. As I add baffle counterclockwise around the engine, the next baffle behind the #4 cylinder head fits nice. After that, the baffle covers starts at the barrel of #4 and ends at the rear of the case at the middle of its seam/joint behind the Flow Divider. That is the first piece I want to give attention to.


The 1st photo below shows bolt a hole, and a cushion clamp/bolt assembly with red arrows. Vans designed this piece to be attached to the case via the bolt hole using a bushed AN4 bolt that gets attached to the case. The bolt is to go through the hole, then a bushing about 1" long, then into the case. My case does not have anything to receive that bolt. I don't believe it is industry best practice for a guy like me to fabricate one by drilling into the case, but behind the hole is about an inch space then a part of the case that is about 3/8 thick and flat, so a bolt hole could go there. But I'm not drilling one. I decided to secure this baffle piece via the cushion clamp/monodeck nut and AN3 bolt with a bushing between the cushion clamp and the baffling.

Therefore, I work alone, and need feedback about this attachment. Does my attachment seem prudent, or is there a concern with it? Is there a better method to secure it?

My next question concerns the baffle piece behind cylinder #3. The first photo shows the right upper engine mount with a bolt hole surrounded by three small holes. (The piece was trimmed near the engine mount attach bolt/nut to fit my case.) This is a bolt hole with three rivet holes intended to attach the baffle to the case. The baffle would get reinforced with a .032" thick reinforcement around the bolt hole that are attached with rivets. Once again, my case does not have a hole to relieve a bolt. The case areas here is very thick, and In a more modern case, I bet it is to receive a course threaded 1/4 bolt.

The second photo shows the back of the engine and you can see the oil dip stick. The third photo shows the dip stick with a cushion clamp positioned near the baffle. I envision a sheet metal flange with a 90 degree bend in it riveted to the baffle and attaching to the cushion clamp so I can get support from three different axis of movement.


View attachment 53357View attachment 53358View attachment 53359

So, my plan is to go behind the baffle piece and secure it somehow via a fitting that will get attached to my oil dip stick with a cushion clamp.

Bad picture links in second post


Sent from my iPhone using SuperCub.Org

Lets try this again. These photos go with post #2 and concern the baffle behind cylinder #3. The first photo shows the bolt that penetrates the right upper engine mount, and the second has two arrows. One point to that engine mount, the other points to the oil dip stick that I may use with a cushion clamp to help secure the baffling.

Did you get the right kit from Van's? They have one for both parallel and angle valved engines. Assuming you did, your options are to drill the case where needed or fab mounting points like you show. Cushion clamps may not survive with engine heat. I don't think I've run into one without the holes for mounting.
You'll end up cutting a lot off the tops of those baffles.

Maybe it's just me, but I would never clamp anything to a tube, especially a push rod tube, to support it. Most small Lycomings use tabs from the rear baffles to accessory case bolts for support in the middle and connections with the side baffles for end support.

Web

wireweinie said:

especially a push rod tube,

Web

Click to expand...

that was my first thought also.... no reason why, just wouldn't be my choice for a big thing like a baffle....

spark plug wire, sure/ok.....

You really ought to make a visit to a nearby airport for a look. Go to the maintenance shop and talk to the mechanics. Look at several different airplanes. I see several things in your pictures which are a bit hoaky (meaning could be troublesome later). Also you should not have to drill any holes in the engine, Lycoming supplies enough. Also extra holes could later on render the engine not airworthy for an overhaul, if you care.

Bearhawk Builder said:

Did you get the right kit from Van's? They have one for both parallel and angle valved engines. ........
You'll end up cutting a lot off the tops of those baffles.

Click to expand...

Yes, This is a Vans Baffle Kit for Parallel valve engines. The fit around the valve cover indicates that I ordered the correct kit.

wireweinie said:

Maybe it's just me, but I would never clamp anything to a tube, especially a push rod tube, to support it. Most small Lycomings use tabs from the rear baffles to accessory case bolts for support in the middle and connections with the side baffles for end support.

Web

Click to expand...

Thanks Web; Thats why I asked. I'll be removing it and look elsewhere for support. I have glanced at the accessory case bolts and will shift the support from the push rod tube to fabricated tabs connecting to the the accessory case bolts.

skywagon8a said:

You really ought to make a visit to a nearby airport for a look. Go to the maintenance shop and talk to the mechanics. Look at several different airplanes. I see several things in your pictures which are a bit hoaky (meaning could be troublesome later). Also you should not have to drill any holes in the engine, Lycoming supplies enough. Also extra holes could later on render the engine not airworthy for an overhaul, if you care.

Click to expand...

Thanks so Much, Skywagon. I'll do that. Getting thing kosher shouldn't comparable to an easter egg hunt. I can see I need help.

Brooks