mppickett posted:I've started the Hoover mods to the case, lifters and rockers. If you've never read through Bob Hoover's blogs, you might want to take a look. Brilliant work and observations from a guy who converted VW type 1 engines for aircraft use in Alaska. Here's a link to the HVX "Hoover mod" oiling post: https://bobhooversblog.blogspo...007/05/hvx-mods.html
Lots of folks have taken the mods and clarified things, created video instructions, etc, but I enjoyed going to the original source and getting a feel for the guy who came up with them. He passed away from cancer in 2010 and the last 18 months worth of blog posts have updates on his fight with the disease in addition to a wide ranging set of observations on how to build engines and planes that won't kill you. An amazing guy.
In any event, my 12" long 7/32" drill bit arrived and I slowly and carefully extended the right side cam oil gallery and then did the treacherous plunge drill down to intersect the new gallery extension without breaching either the internal or external case walls (phew!). Not hard at all, just a little nerve racking. One absolute key is to go slow and frequently pull the drill back to clear the magnesium dust and chips so they don't think about igniting. I did not use any cooling liquid, I just was very patient. The bonus was a big pile of magnesium dust and chips that made a serious fire display when ignited outside with a propane torch.
Next I'll be finishing up the various case, lifters and rocker arm tweeks that allow the new oil gallery to cool and lube the right head adequately. Then drilling and taping for the replacement NPT gallery plugs and a thorough cleaning of the oil galleries and other engine parts before the final air blow out and securing the new gallery plugs. There's a great link for gallery plug steps and comments on the #4 bearing restriction plug question (many different opinions on how to handle this plug that restricts the amount of oil that gets to the #4 bearing in an attempt to prevent oil leakage from the front pulley as the bearing wears). I'm inclined to drill a 3mm hole in a plug to limit the oil flow even though the #4 bearing itself has only a 2mm hole. @ALB, I saw you commenting on this 15 years ago on samba or shoptalkforums, any thoughts these days? Also any thoughts about best approach for rockers and rocker shafts mods to take advantage of the new oil flow?
Here the gallery plug link I thought brought a lot of info together: https://www.shoptalkforums.com...hp?f=34&t=132558
You'll see a little discussion about whether Bugpack or EMPI plug kits are better. I think this is now moot since the Bugpack plugs are also now EMPI labeled and appear to come in the same sizes. General wisdom seems to favor aluminum plugs secured with Loktite blue.
Mike
Good morning Mike- I've done the oil galley extension with a 3/16" drill in a junk case; I know Bob talked about using 7/32" (or even 1/4" if the smaller size isn't available) but all the reading I've done says the 3/16" is more than enough to keep the right side rocker area continually bathed in oil. I'm not criticizing what you did- I'm not sure it really matters what size you make those passages, as long as you're feeding oil constantly to the head. I chose the smaller drill size to make the likelihood of breaking through the case less (which was still only 1/16- 1/32" thick after we drilled through to see, although filling the depression with epoxy makes it a moot point), but I've also wondered if the larger galley size would actually give more oil pressure at the rockers, with better spray patterns toward the valve stems and springs, given the number of outlets we create with these modifications? So many questions...
I worked for a short time in a friend's VW shop (winter '79/80), took apart a fair number of high mileage engines in preparation for rebuilding and more than once Don made the observation that there was always more scoring and wear on the rockers out of the right side head. The solution at the time was to polish the shafts, reverse them and as long as the bushings in those rockers weren't totally fubar, install them on the driver's side head. We talked about how there must be inadequate oiling on the 1 side, but since so many engines went 100,000 (and more) miles before needing refreshing never gave it much more thought (that would have cut into after-hours beer time, and we couldn't have that!). 25 (or so) years later, first time I read Bob's "HVX Mods" article, the light came on pretty quickly and I've been a believer ever since.
On the Samba, STF and Cal Look Lounge I have either started or participated in threads discussing the Hoover modifications and not 1 person who's done them has reported any downside (other than the danger of going through the outside of the case, which is easily fixed with a little epoxy). The drilled passageways and notching the lifters provides full time oil to both heads and the rocker detailing eliminates so much wear (and heat). People have drilled pushrods for valve spring oiling and heat removal, while others have either notched the rocker sides or drilled through the rocker bodies to the same effect. With more oil in the right side head comes more stable temps and the a/f mixture will be closer to ideal more of the time, meaning the engine will make it's best power more of the time.
This is not the first time I've said this- even stock engines will benefit from these modifications. And yeah, if you took the time to put together a how-to (with lots of pics, of course!) I'm sure it would be appreciated. I'm looking forward to hearing your observations once it's been running awhile. Al