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HDC Pan Rocker Bearings and Arms

Moderators: Curt!, Pa

Post Tue May 29, 2007 8:13 pm

Posts: 1536
Location: S.Calif.

Here's a set of HDC rocker blocks and arms for my '56 heads. HDC has been making these for at least 20+ years. Installed the rocker arm will slowly drop on it's own weight. No way would those '48 arms (shown below) do that.
Problem was that the flexloc nuts Accurate sent with the heads are too wide for one post of the rocker blocks. You have to grind away some material or find 7/16 or smaller facet nuts.
Here's a set of -50 heads Lakeside Bill built for me in 1988. Intake blocks are -48, exhaust block is aftermarket HDC. Check the nuts, one set has 7/16 hexes, the other 1/2" ! Old Bill was trying to do everybody a favor and build them cheap. He helped alot of people get started with the hobby. Actually both style of nuts allow you to use a regular socket to tighten them. We tighten them to 15 ft. lbs. Clymers book says 18-20 ft. lbs. H-D doesn't specify a torque spec that I know of.
You don't need the intake oilers with lead-free valeves and seats.
The intake (-48) rocker arm was stiff at about mid-swing, even so, I put at least 23,000 miles on these heads without a problem. Rarely would my solid lifter pushrods need adjustment. I checked them every oil change.
This is a factory installed felt. It looks like two compression divots near the center of each felt. Wonder how they did that?
Here's new felts installed. First I traced the outline and inlines of the felt , removed the felt and applied a line of 3M Super Weatherstripping adhesive #08008 to both the back of the felt and the cover, comes in black too, instead of yellow. NAPA had it.
Last edited by Plumber on Tue Jun 05, 2007 6:51 pm, edited 3 times in total.

Post Tue May 29, 2007 10:34 pm

Posts: 309
Location: Cranbrook B.C. Canada
Hey Plumber, What kind of end-play do you have on those new rocker blocks and shafts? All of the aftermarket sets I`ve seen have excessive end play. Who is HDC ? I never heard that name before. Thanks in advance.

Post Wed May 30, 2007 2:22 am

Posts: 1536
Location: S.Calif.

0.0045" on one of them and 0.008" on another one. Factory spec's were 0.004 - 0.025". Accurates were honed.
I regret taking material off one post of each of them in order to gain socket contact. I could have waited and found some smaller nuts, or used the old flexloc, but I didn't, so don't do what i did, is all I can say about that.
The HDC are a nice piece. I didn't know what brand of bearings were on those heads old Bill put together in '88, but when I took the top off, there it was.. HDC. The Accurate heads were done in 1999.
What surprised me were how tight the -48 rocker arm was in the bearing, and the fact that I got so many trouble free miles from them, without bending a push rod or worse. I doubt if Old Bill honed them, and the Clymer book reported the -48 bearings as being not very good about oiling since the first models were un-grooved inside the top.
Who's HDC is going to be another one of those who's Zel mysterys I think. You can tell by some of the casting slag along the edge of the top (brass) bearing that they're from the far east. And if that doesn't convince you, some of the tiny air pocket holes in the cast iron will. :wink:

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