------------------------------------------------------------------------- Using the lathe, I groove the rocker-arm shafts in the locations shown. Inside the rockers, I use a Dremel tool (or similar) and a carbide burr to CONNECT the two oil passages.
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The HVX mods begin with a full-flow oil filter. Then the crankcase is modified so as to INCREASE the amount of oil reaching the heads by eight-fold. There is no sense in making mods to the valve train until you have made the mods to ensure an adequate flow of lubricant to the heads.
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The full set of HVX drawings is NOT included in the blog. The HVX mods includes the use of the Soobie/Ford type swivel-foot adjuster, for which the adjuster-end of the rocker-arm must be thinned down... as shown in the drawing you've cited.
All tolled, there's about 125 CAD drawings, a bit much for the blog. But every time I've posted them publicly someone starts flogging them on eBay. I'm trying to get all of this information into a POD book but the size of the book (more than 3 Megs) and the small size of the market (ie, there's not that many owners of air-coolled VW's) makes it a tough sell.
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It is a waste of time to do ONLY the valve-train mods -- there simply isn't enough oil to do the job. The key is to get more oil out to the heads. Once you've done that, you'll see the need for the grooved rocker-arm and connecting the oil channels in the rockers. The internal oil channel in the Ford/Soobie-type adjusters allows them to function as SPRAY BARS, allowing the extra oil to pick up a lot more heat.
As for the grooves and other mods, you will find their functional equivalent inside EVERY modern-day engine (including the Type IV).
The lubrication system was marginal in the 1300. For larger engines operating at higher rpm, you have to go back to basics and resolve the root problem. A big advantage of doing so is that once you've provided more oil to the heads you will eliminate the snapping hair- pins, worn washers and galled rocker shafts, which means you can leave all that expensive after-market valve-train stuff on the counter.
-Bob Hoover