SonexBuilders.net

I bought the new machined aerovee sump plate from sonex this past summer while out at Oshkosh. I just got around to installing it this past week and unfortunatly it doesn't fit. When I install it the studs coming out of the case are not long enough. The normal sump plate fits fine but since the machined plate is thicker there are maybe 1 to 2 threads exposed once the plate is pushed all the way against the case.

I contacted Sonex to ask what the deal was and they said sometimes the studs are short and I should remove them and replace them with bolts. I tried doing that last night. All the studs came out fine except for one. There is one stud that is extra long, goes through the case and has a nut on the inside that holds down the oil pickup tube. It is impossible to remove that nut without splitting the case. Even if I did get it loose I wouldn't be able to hold it in place to put a longer stud in.

I sent Kerry another e-mail this morning asking what to do at this point but honestly, based on the last suggestion and not knowing about the oil pickup tube as well as some other answers I have recieved in regard to the aerovee I am starting to have my doubts about his knowledge on this engine.

I am wondering if anyone else has run into this problem and what they did to resolve it. I hate to throw $30 down the drain on a cover that was from the factory and supposed to fit.

Keith
#554

Just a suggestion but could you not machine the nut relief deeper. If it is made of aluminum you could use a plunge router with a straight plunge bit of the appropriate size.Remove enough material so that around the holes you have enough thread exposed.Actually it would probably be easier on a drill press with Brad point bit or a Forstner bit.

That is what Kerry suggested yesterday as well. It will probably work but I am still dissapointed in spending money on a cover from them that wasn't designed to fit properly and then having to modify it ruining the annodizing in the process. It will also now require two different wrenches to remove the cover as well. Not a big deal in the grand scheme of the aiplane but still a disappointment.

I did find another possible solution from an aircooled vw car site. They are called step nuts. It is basicly a piece of hex bar stock that is machined round at the end and a hole is drilled and tapped to match the stud (6mm). They allow you to "extend" the studs to fit the bigger plates. The only problem is that to buy 6 of them with shipping and handling I am going to spend more on the step nuts than I did on the cover. I may try making some on my lathe if I get some free time. If it works I will post pictures up to the group.

Keith
#554

This project seems to be rapidly becoming more trouble than it's worth. Unless the new cover actually adds functionality and does more than look nice, I'd just skip it. Return it to Sonex if they'll take it, otherwise consider it an "educational expense" and craigslist it.

I agree that this cover is more trouble than it should be. The problem I have with the stamped covers that come with the engine is that they are notorious for leaks. I had a small leak from mine (1 to 2 drips every few days) and was hoping that this cover would fix it.

Keith
#554

Hi Keith ,

How long are your studs ? How long do they have to be to make it work ? Not really helping with your problem but it might be useful info for people considering this part ( like me ).

Marc