How to Rebuild a Corvette 454 Engine - Part 8 - Page 3

Here's the new timing set ready for installation. I opted for a double roller timing set from Comp Cams.

The lower timing gear is press-fit onto the crankshaft snout and can be a pain to install. Since I didn't have the special installation tool on hand I put the gear into a 350 degree oven for about fifteen minutes or so. When it was good and hot I took it from the oven and immediately installed it on the crankshaft snout. The heat expanded the gear enough so that it just slid into place, a little bit of oil on the snout helped the process as well.

Because I'm going to a retro-roller cam setup I needed to install a cam button to prevent the cam from "walking" forward. Hydraulic flat tappet cams are profiled to prevent significant forward movement of the cam but this isn't the case with retro-roller setups. The cam button is placed in the center of the cam timing gear and presses against the timing cover to limit forward camshaft movement.

Here the cam button has been installed in the timing gear. The gear itself bottoms against the block to prevent backward movement, the cam pressing on the timing cover prevents forward movement.

Because the timing cover is used to resist cam movement I wanted to use something more rigid than one of the flimsy stock timing covers. In the end I decided on a polished cast aluminum cover. It cost a bit more than a stock one but it'll work much better. Of course the cast aluminum cover is thicker than a standard cover so I'll need to machine down the cam button to achieve the proper camshaft endplay.

As I pointed out a few updates ago I had left the cam plug out for the time being. I had done so to allow access to the back of the camshaft to be able to check camshaft endplay. Even though I've installed a cam button the goal is not to achieve zero movement. Instead Comp Cams recommends between 0.005" and 0.008" of camshaft endplay. To measured endplay I used a dial indicator and set it up as shown below. With the dial indicator in place I gently pried between the block and the side of a cam lobe to move the cam forward and backward. It takes very little pressure to move the cam back and forth - if it doesn't move you're probably at zero endplay. It took quite a while to get the cam button machined to provide the proper endplay (removing just a little material at a time), but eventually I ended up at 0.006". I didn't want to go down to the minimum tolerance since I realize the timing cover gasket will likely compress over time and will reduce endplay by a bit more.

Once the end play was set I removed the timing cover one last time, cleaned the gasket surfaces with lacquer thinner, applied a small amount of black RTV sealer to the timing cover flange and block, put the gasket back in place and bolted the timing cover down. Before removing the dial indicator I double checked endplay one last time to verify everything was as it should be. With the cam in place I then installed the cam plug in the back of the block using a little Permatex No. 2 sealer to prevent any oil leaks.

That's all for this update! Next time I'll be installing the cylinder heads, hydraulic rollers, rocker arms and determining pushrod length. Stay tuned!

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