So after lapping the valves on #4 and the #3 intake, this is where I ended up:
leakdowns, taken hot
1 80/76
2 80/79
3 80/67
4 80/67
Passing in theory but I don’t like the way it runs. Partly due to the imbalance in compression, but I think something else is going on. I thought I found the smoking gun with the induction leak, but it is still really mixture sensitive at WOT and my static RPM is under 3000.
I generally start my annual in January. Plus this has to be right. So I need to dive in and figure out what is going wrong.
#3 intake and #4’ exhaust seem to be the culprits. I’ve pulled a head off my spare AeroVee and am cleaning it up to try it. I believe the springs and guides are good.
The manifold that was leaking is well sealed now. I need to look at everything else.
Some of my cylinder studs are longer than they need to be. It always bothered me a little. Dead weight, and low clearance on the manifolds. I had to trim some during the build for the rockers, and then trim them again when I changed to 1.25:1 rockers, but I did the bare minimum.
Compression when turning the prop by hand is awesome. The airplane rocks on the gear. I’ll give another shot at the leakdown test after I run it, when it’s warm.
We were flying back from Racine today on just the primary ignition, and had an RPM loss and vibration. Turned on the secondary ignition and it was happy again. Back at home, on the ground, did some running while monitoring the EGTs. Front right cylinder is cold.
Pulled off the cowl, looked for melted or disconnected plug wires. All looked good. Pulled the #4 primary plug, looked good. Swapped in a magnetron from the spare AeroVee, plus I was due for head torques, valve adjustment, and I did the oil change 4 hours early since I was down anyway. Just ran it. It’s good again. Will go from the idle stop to WOT on either or both ignitions. So I think just a bad magnetron. I’m thinking about adding blast tubes for the magnetrons.
The #3 pushrod tubes were leaking again. I’m trying something different on those 2, which are typically the leakers. I put the lower seals onto the spring loaded pushrod tubes with permatex #3, and put some hylomar blue on the conic part of the seal. I also did some hylomar on the conic part of the middle seal. For the seal to the heads, I’m doing the same thing as always - cylindrical part of the seal dry, oil the conic surface. Oh I also stretched the springs a little, maybe 1/8".
oh yes! I put blast tubes on the magnatrons, the two coils and on the regulator.I used 1 in dia tubing, from the top center area above the block centerline, thru several specifically built directors for air.
So, a milestone in my quest for the elusive dry AeroVee. It’s not dry, I’ve got a little oil on the floor, in the cowl, and the belly is filthy. But I have not added any oil in the last 25 hours, since the last oil change.
So what changed? I installed a Sonex air-oil separator, and I think my case back pressure must be lower. I also could not get the #3 pushrod tubes to seal. I glued the conical seals on the end to the tube with permatex #3, and used a little hylomar blue on the conical part.
Plus I sacrificed 3 chickens at midnight during a full moon. I was going to keep that as a trade secret but had a change of heart.
So here’s another AeroVee oddity. As I’ve documented, I did a lot of performance enhancing work - some porting, higher compressions, more valve lift, and so on. But lately it seems performance is lacking. I’ve been seeing just a little over 3000 static and maybe 3070 in climb. I used to see nearly 3600 WOT, but I can’t get over 3400 anymore (level flight). So last night, before the oil change, I removed my air filter and did a static run. RPM increased over 100, I was seeing 3170. I have a really oversized K&N filter and I washed and oiled it at annual, as always. I wonder if I screwed it up somehow. I’m going to try again and if it doesn’t improve, it’s probably back to chickens.
Odd. Temp and humidity the same as when you were seeing the higher rpm’s? I noticed my rpm is down slightly from the cooler temps, but not that drastically.
Sorry can’t comment on the filter. I’m still using the stock sized k&n. Vacuum the debris off annually, but have not washed it or re-oiled it.
It is commen for folks to over oil the KN filters. So much so, that Rotax put out a video on how to do it properly and stating lower performance if over oiled.
Rene’ is aloso on to something with the air temp, humidity and density.
