Conn Rod Problem?

[NWade]

Hi All,

So as I begin assembling my AeroVee Turbo, I've noticed some inconsistencies in my rods...

1) Despite being labeled "ACV-P06-33" on the box, the rods have hex nuts (not the star nuts specified in the manual). Anyone else experience this? I'm guessing I should just follow the "P01-33" hex nut assembly instructions, but I want to be sure.

2) The rods have had their stamped numbers ground off, and lightly-engraved numbers are present instead. The numbers are on one side of the rod for 3 of them, but the other side of the rod for the 4th one. I can tell this orientation by the forged "CB" on the rod (Also because the bearing anti-rotation notches are opposite on this rod). I would expect all the rods to face the same way, or for them to be staggered 2 & 2... is it possible that these numbers were engraved incorrectly on one of the rods?

Any thoughts or comments from experienced builders?

Thanks!

--Noel

[jjbardell]

I'd talk to Kerry at Sonex. Mine were all stamped and aligned well.

[NWade]

I'd talk to Kerry at Sonex. Mine were all stamped and aligned well.

Thanks, I already emailed them but posted here as a sanity check in case I'm overlooking something obvious or worrying about nothing. :P

Here are photos, for reference -

Group Shot: https://flic.kr/p/SoiDnq
Odd-Rod-Out (notice engraving relative to anti-rotation notches): https://flic.kr/p/Raibss
The other three rods look like this: https://flic.kr/p/SfMpk4

Also, the manual says the "P06" rods have star nuts that are torqued differently; but mine have hex nuts. Not sure if that means they're actually "P01-33" units or not:
https://flic.kr/p/Raibyu
https://flic.kr/p/SoiD6d

--Noel

[jjbardell]

Personally, I'd want new rods. My were all stamped properly and looked identical. Those look like old leftovers.

[mike.smith]

Mine were all hex nuts. Mine were stamped neatly, and were all in the same orientation.

[NWade]

So Sonex was very helpful in explaining the etching as the new way Rods are being marked by their vendor. They claim that these are the preferred rods, but offered to send me a new set for free and RMA the old ones - hooray!

The new rods showed up and I found they have the same "oddity" as the originals (3 oriented one direction, 1 oriented the other way)... I made a little video illustrating what I'm talking about: https://flic.kr/p/SA2qa8

Am I jumping at shadows? Anyone have info or an explanation for what I'm seeing?

Thanks a bunch,

--Noel
Sonex #1339

[thomas]

Hi Noel,

Your video made clear your concern - thank you. I looked through my box of AeroVee Turbo parts (circa Oct 2016), found my connecting rods, and they have the same pattern as your sets: 3 rods engraved on one side and 1 rod on the other. If there is a significance, it escapes me! Please let us know what you learn. I still have the whole airframe to build before I get to sink my teeth into the engine.

Thanks!
Paul

[NWade]

Hi Noel,

Your video made clear your concern - thank you. I looked through my box of AeroVee Turbo parts (circa Oct 2016), found my connecting rods, and they have the same pattern as your sets: 3 rods engraved on one side and 1 rod on the other. If there is a significance, it escapes me! Please let us know what you learn. I still have the whole airframe to build before I get to sink my teeth into the engine.

Thanks!
Paul

I'll be sure to post what I learn!
Its worth noting that the "How to Rebuild your Volkswagen" book specifies an alternative method for orienting the conn rods on the crankshaft (and its one that would tend to argue against using the etched rod markings as an alignment tool, in the case of my rods). So if I wind up stumped I'll use that method, and report that here.

--Noel

[NWade]

Here's an update:

AeroConversions worked with the Rod Manufacturer to clarify some points. And I wouldn't be surprised if AeroConversions makes some minor revisions to the AeroVee Assembly Manuals in the future - since they're generally good about providing the latest info to folks. But different rods have been supplied over time (and the manufacturer may have iterated the design/manufacturing of these rods over time as well), so I don't want to make any recommendations that may not apply to other engines besides my own.

I will say that the instructions on page 118 in the book "How to Rebuild your VW Air-Cooled Engine" appear to be appropriate for my engine; and for my rods the etching on the side of the rod is not indicative of which side needs to face "up" (...the manufacturer claims that up and down are not critical for my particular rods as they are not asymmetric). Note that the etching is still important for matching the rod & rod-cap, and to assemble them in the correct orientation relative to each other!

I am very appreciative that the Sonex/AeroConversions staff listened to my concerns, shipped me a second set of parts, and followed up with the manufacturer to ensure that the proper information was gathered!

--Noel

[thomas]

Noel,

Thank you for sharing this information. I have book marked it and will reread it when it's my turn to assemble the AeroVee. I already own a copy of Tom Wilson's book, so your references will come in handy!

Paul