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.
