End Play when hand turning prop

[radfordc]

All I can say about the cracked valve seat is that my engine has been that way for at least 200 hours. The local VW shop says that most VW's with oversize valves have this crack and that as long as it doesn't cause excessive leakage it isn't a big problem.

[Rynoth]

Sorry to hear about all your issues. I'm currently in the middle of my Aerovee build and am learning about all of this stuff as I go. I will definitely reccomend to you the following book, which is also suggested by Sonex in the Aerovee manual. It will do a good job of answering many of your questions.

http://www.amazon.com/Rebuild-Volkswage ... 0895862255

One thing I'm curious about... when I was putting my crankshaft and camshaft into the case, I noticed some very close tolerances between the connecting rods and the camshaft. Given the amount of fore/aft play you had in your crankshaft, is there any evidence of connecting rods contacting any part of the camshaft?

Regarding your possible crack between valves, the above book recommends grinding away material until evidence of the crack is gone (i.e. remove the stress riser.) Within reason, this will keep the head serviceable.

[daleandee]

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[grevaly]

I am wondering if your front brearing was not seated on the crankcase dowel pin causing the front of the crank to be out of center and the prop hub
rubbing the front of the case where it has been machined for clearance of the hub and causing the bearing to wear into the crank shaft. When I put my
engine together I had let that bearing pop out of place and on my initial tightening and checking for smooth rotation of the crank noticed the problem and was able to correct it.
It is a good thing you tore that engine down.

[radfordc]

Dale, you're right. The big valves used in CB044 heads are so that the engine can turn 7000 rpm. At 3500 rpm the valves could be much smaller. The problem of course is sourcing such heads. All the stuff we use is made to satisfy the dune buggy crowd.

[rizzz]

I am wondering if your front brearing was not seated on the crankcase dowel pin causing the front of the crank to be out of center and the prop hub
rubbing the front of the case where it has been machined for clearance of the hub and causing the bearing to wear into the crank shaft. When I put my
engine together I had let that bearing pop out of place and on my initial tightening and checking for smooth rotation of the crank noticed the problem and was able to correct it.
It is a good thing you tore that engine down.

That's what I'm thinking as well.

jfuerst, what did the dowel pin look like on that front bearing?

[lutorm]

I thought the axial play on our Aerovee was excessive too. It measures to something like 0.020-0.025", and when I went looking I found this thread. This engine has ~140h on it. I guess the conclusion of this thread was that we should split the case and verify the condition of the thrust bearing?

[RodgerC]

This is pure speculation...My AeroVee that I’m currently rebuilding at 110h also had around 0.020” end play with no obvious thrust wearing wear at time of tear down. However, when I originally built it it had 0.005 end play, PRIOR to me applying RTV sealant to the dowel pins and torquing the flywheel.

I’m going to hypothesise that the 1/8” sealant bead adds another 0.010 clearance to the thrust bearable end float.