The Studeblogger

Sunday, November 15, 2009

Hey... your head is loose!

While I've been occasionally accused of not having my head screwed on tight enough ;) I'm talking about the bolts on your engine's heads in this case.

StudeKen (Ken Pyle, who rebuilt my 259) reminded me that the head bolts needed to be re-torqued after the engine had been restarted and run a bit, which mine now has. So, yesterday being a beautiful 72 degrees here in SoCal, I decided on a little StudeWrenching in preparation for road-worthiness.

First step is pulling the valve covers. If you're a GM guy like I was, you're probably used to a lot of hold-down bolts around the base of the covers, as seen below on my '67 Pontiac. Some other brands have quite a lot more bolts!

In contrast, Studebaker valve covers are easily removed without fumbling around by just unscrewing the two bolts in the center of the valve covers (4 bolts on older models):

The studs protrude through the valve cover through rubber seals, easily available from SI and other vendors. Just undo them, and pull the valve cover off (after removing the spark plug wires, of course). The valve covers seal to the heads using re-usable, soft neoprene rubber gaskets, and they take a little pulling to get loose; don't be shy, just grab the oil filler tube and give it a gentle yank.

With the valve train exposed, you'll have easy access to all the head bolts. There are 18 of them, as shown in the figure below, taken from the factory Shop Manual:

The manual specifies 55-65 lbs.-ft. of torque for each bolt. I usually split the difference, and so set my wrench right in the middle at 60 pounds for this operation. Note that the diagram shows a specific sequence for tightening the bolts; although this is specified for head installation, I used it for the re-torqueing operation as well (better safe than sorry!) Note that the 5 center bolts under the valve cover get torqued twice.

I was surprised at how loose a few of these bolts had gotten with just some running-in-place in my driveway! They all broke loose with the first pull of the wrench, on average took a quarter turn before the wrench clicked to indicate torque. A couple of them took nearly a full turn, specifically the two furthest forward adjacent to the water manifold.

I used a 12" extension to get the proper leverage on the torque wrench for most of the bolts, but a couple - those furthest toward the firewall - needed a shorter extension to clear certain obstacles. On the passenger side, the flange for the heater plenum interfered; on the driver's side, the steering column forced using the 6" extension. I also had to shift the transmission's column shifter from Park to Reverse in order to drop the shifter linkage out of the way.

After you're done, the valve covers go back on easily. In the photo above, you can see the rubber seal iin its channel around the rim of the valve cover; make sure it's seated properly and not dropping loose, otherwise it could be cut by the interior flange and seal improperly - and there's nothing worse than engine oil dribbling onto your hot exhaust manifold while you drive!

The Stude shop manual calls for 14-20 inch-lbs. (!) of torque for the valve cover nuts. Now, maybe back in the day everyone had tools calibrated in inch-lbs. just lying all over the place, but here in the 21st century you're more likely to find a dinosaur bone in your backyard than such a device at your local Sears.
14 inch-lbs. is not a lot of torque, so I just used a nut driver to tighten the nuts hand-tight, which is all the neoprene seals really need.

All done! Put the spark plug wires back where they belong and DON'T forget to reattach the throttle return spring to the wire clip welded to the driver's side valve cover.

Update, January, 2011: There's a little additional information about proper torquing procedure. Check out this post.

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