I have an IO-360-A1B (200 hp angle valve) on my RV-7. Initially I filled that little rectangular void area in the cowling with foam/glass/epoxy because it was interfering with my inlet ramp installation - at least that's what I originally thought. But it turns out the reason the void is needed is to clear the front right 'ear' of cylinder # 1 where the baffle attaches and it also turns out that the inlet ramp is not interfered with by the void since the baffle material folds over against the ramp and the seal is just fine.
During the 25 hour fly off time in my plane, aerobatics were performed which naturally causes the engine to move around quite a bit. RV's use softer vibration mounts than acro planes - softer mounts allow more engine movement as a trade off for vibration reduction in the cockpit. Anyway, when I pulled the upper cowl, I had a gouge inside the cowling and a hairline crack showing on the outside of the cowl exactly in the area just where the baffle attach screw is located on the cylinder ? right where I filled up the void. That showed there is very little clearance between the cowl and the big engine as it moves around during acro and probably during other maneuvers (bounced landings, maybe) especially if you initially install the cowl a little low relative to the spinner to allow for eventual sag in the lord mounts. By the way, the upside of that is that when the engine eventually sags on the mounts so that spinner and cowling match up nicely, it also actually helps make more clearance.
So, I dug out the material I?d filled the void with and reglassed the area, then I filed/ground the ear down on the cylinder to an angle and I even filed/ground the attach screw head at an angle to make the clearance work better. I cut and filed the baffle and adjusted the baffle material; the side baffle is just barely there at that point ? just enough to attach it to the cylinder. By the way, Pitts S1T owners are aware of this cowling clearance issue (AEIO-360-A1E engines).
There?s 32 hours on the plane now and I pulled the cowling this week to bleed the brakes after repairing a leaking Matco master cylinder (not this topic, but you might consider running a 1/8? pipe tap a turn or two in Matco master cylinders and use Loctite 567 when you install the 90 degree fittings into the tapped holes on Matco masters). There?s no further damage to the cowling just yet. And as a side note, the engine has sagged a bit and the spinner/cowl almost line up now.
I don?t know how much clearance is an issue in other engines, but I note on most sites with pictures of 180hp engines, there?s a pretty tall bit of baffle sticking up above cylinder #1.
CJ
