Head Assembly

With the heads milled and cleaned, we're ready to assembly the hardware. As mentioned earlier, we opted to get most of the valve train hardware from Crane. This ensures we get the correct springs, retainers, etc. to match our cam specs. One of the most frustrating things to experience is a valvetrain that doesn't go together right, or springs that float when you go to push the engine. Sticking with the manfacturers matched components all but ensures success.

Solid roller cams require the use of extremely high spring pressures. We're using Crane (Part No. 99893) double springs with 165 lbs. seat, and 426 lbs. open pressure; with an installed height of 1.750". Installed height is a critical factor when installing any set of valve springs. The pressure rating of the spring will vary with height, which directly affects its ability to control the valves. More often than not you will need to use shims to meet the installed height specs for your springs. Shims come in three heights, 0.015", 0.030", and 0.060". However shims come in a variety of inner and outer diameter combinations; so it is extremely important that you select the correct shims. In the photo series below we'll take you though the process of correctly setting up the valve springs and related components on a cylinder head.

Setting up the Valve Springs

Start by checking the installed height. Measure with a small macinists rule or spring micrometer from spring seat to underside of the retainer. Add shims to decrease space, or machine the seat to increase. The objective is to meet the specification listed on the cam card.

Only use hardended/heat treated shims. Otherwise you'll end up with shrapnel in your motor. The correct shim will properly locate around the valve guide, and/or fit spring seat, as well as be the correct diameter for the spring being used. Shims usually come in 0.015", 0.030", 0.060" thicknesses.

The majority of aftermarket heads come with guideplates and screw-in studs. This set-up is offers increased stability, strength, and adjustbility over rail type or pedestal mount rockers. Whenever possible we recommend stepping up to 7/16" studs rather than 3/8" for maximum strength. Some heads (such as Worlds) require using sealer on the stud threads as the holes are open to the head coolant passages.

There are two major types of oil seals. The "umbrella" seal rides the valve stem, while the Teflon seals fits snug over the guide and "scrapes" the oil off the valve stem. Teflons are better at controlling oil through the valve guide, and more importantly they clear double springs and high-lift cams. Teflon seals come in 0.500" ID or 0.531" ID, so the valve guide outer diameter may have to machined to this size to allow the seal to "cap" the guide.

The valve springs are installed with this handheld spring compressor (Craftsman brand). Be sure to wear eye protection when handling compressed valve springs, they hold quite a bit of force.

The final step is to check the coil springs for binding. Install pushrods and rocker arms for at least one cylinder. Rotate the crank until the valve is fully open, and with a feeler guage check for at least 0.060" clearance between the center two coils.

(Intake Selection and Preparation)
Part I Short Block
Part II Induction
Part III Installation
Part IV Dyno Testing

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