Cylinder Heads - Bare Head Assembly 101

Sucp 1212 01 Cylinder Head Assembly Bare Head 101

Doing things yourself when it comes to engine assembly can be very rewarding. We're not saying there's anything wrong with having someone else do the work, just that when you do it yourself, there's a bonus feeling of accomplishment and pride.

If you're a rookie when it comes to engine mechanics and assembly, having a shop put together your short-block is one of the smartest things you can do. Assembling bare cylinder heads yourself and setting them up for your particular engine has several advantages, however. One, you can hand pick the parts such as valve-springs, retainers, valves, rocker studs, etc., to best suit what you're building the engine for. Flat tappet and roller cams require drastically different valvesprings, the same as hydraulic versus mechanical/solid lifter cams. If you're going racing, you might want to lighten the valvetrain with titanium valves, beehive springs, titanium retainers, etc. Regardless of your application, starting with a bare head gives you many options.

To show how easy assembling heads for a street-oriented application is, we called our buddies at RHS for a set of their Pro Action small-block 23-degree bare cylinder heads, PN 12053. This is a great street head with a lot of room for performance and porting/modifications if you so desire, retailing for about $633.00, fitting into most budgets. Don't be alarmed though, the steps we're going to show will work with any small-block head, iron or aluminum. So, follow along as we give you a crash course in bare head assembly.

Part	Part No.	Price
RHS Pro Action 23-deg. Head	12053	$633
RHS Cylinder Head Assembly Kit	12987	$165
Comp Valvetrain Organizer Tray	5327	$37.95
Comp Valvespring Compressor	5337	$99.95

The starting point for our head assembly is an RHS small-block Pro Action 23-degree cylinder head, part no. 12053. It features 180cc intake runners, 74cc exhaust ports, 64cc combustion chambers, angled plugs, 1.550-inch spring pocket diameter, hardened valve seats, premium manganese bronze valve guides, and is set up for 2.02-/1.60-inch valves. This head also has an improved water jacket design for increased cooling and heat dissipation.
The starting point for our head assembly is an RHS small-block Pro Action 23-degree cylind
1 To keep things organized, we numbered each cylinder/combustion chamber.
2 We also marked the head to keep the correct orientation as we moved things around.
2 We also marked the head to keep the correct orientation as we moved things around.

3 To make things easy for the DIY’er, RHS sells complete head assembly kits with everything necessary to equip a bare cylinder head. Our kit is PN 12987, and comes with hydraulic roller dual valvesprings, steel retainers and 10-degree locks, plus-0.100 inch length stainless steel valves, valvespring seat inserts, and steel jacketed high-temp Viton valve stem seals. There are also kits for flat tappet cams, and a kit that comes with beehive design valvesprings if you so desire. Or, you can select the parts individually to better suit your application.
3 To make things easy for the DIY’er, RHS sells complete head assembly kits with everythi
4 Once we unwrapped the kit, we used this handy valvetrain organizer tray from Comp (PN 5327) to keep all of our parts organized.
4 Once we unwrapped the kit, we used this handy valvetrain organizer tray from Comp (PN 5
5 To make sure we keep all the valves matched correctly to the cylinders we lapped them to, the face of each valve was numbered to a cylinder.
5 To make sure we keep all the valves matched correctly to the cylinders we lapped them t

6 Usually valve grinding/lapping compound comes in one grit. To lessen the abrasiveness, you either mix some of the compound with grease or water (depending on the type of compound you buy).
6 Usually valve grinding/lapping compound comes in one grit. To lessen the abrasiveness,
7 A small line of compound is run across the back side of the valve where it meets the valve seat.
7 A small line of compound is run across the back side of the valve where it meets the va
8 To lap valves you'l need a tool like this one, available at most parts stores for under $10. There are also tools/methods that use an electric drill, but we recommend this method for anyone but an experienced engine builder.
8 To lap valves you'l need a tool like this one, available at most parts stores for under

9 Lapping valves is an old technique that helps match a valve to its corresponding seat for a tighter combustion chamber seal. Even though modern machining and production mean there's less tolerance between the two, lapping in the valves helps ensure the combustion chambers stay as sealed as possible. Keeping the valve seated against the seat, use a spinning motion to create the grinding action necessary. You'll feel resistance lessen as the two surfaces begin to mate with each other. Once the valve is fully lapped, wipe down the valve and seat to remove all lapping compound.
9 Lapping valves is an old technique that helps match a valve to its corresponding seat f
10a When assembling heads, it's always good to measure the valve guide OD and check it against the valve stem seal ID.
10a When assembling heads, it's always good to measure the valve guide OD and check it ag
10b If the seals don't fit tight enough, they'll come loose from the guide after a few heat cycles and revolutions of the engine, leading to excessive oil burning in the cylinders.
10b If the seals don't fit tight enough, they'll come loose from the guide after a few he

11 With aluminum heads, valvespring seat inserts are a must. Without them, the spring (and flat wound dampener if so equipped) can dig into the aluminum, sending metal shavings into the oil to wreak havoc in the engine. When you're checking installed height, be sure to do it with the insert installed, as this affects installed height, seat pressure, and open pressure of the valvespring. The seats on our RHS heads are 1.550-inch diameter, but can be machined to a max diameter 1.625-inch. to accommodate larger dual or triple springs, but spring pocket depth cannot be deepened.
11 With aluminum heads, valvespring seat inserts are a must. Without them, the spring (an
12 Next up are the positive Viton valve stem seals. Positive refers to the spring lock around the part of the seal hugging the valve. This maintains tight oil control even as the seal wears during the normal life of the engine. These seals are worth the extra money spent over the old school white Teflon seals, installing easier and lasting longer.
12 Next up are the positive Viton valve stem seals. Positive refers to the spring lock ar
13 Before installing the rocker arm studs, the threads should be coated with a non-hardening sealer, especially critical for the intake studs, which go into the intake runner. This will not only seal against vacuum, but also make sure oil doesn't manage to seep into the intake port.
13 Before installing the rocker arm studs, the threads should be coated with a non-harden

14 After setting the pushrod guideplates in place, the studs are hand threaded in, then torqued to 45 lb-ft in a 25-35-45 process. Using pushrod guideplates mean we won' have to run self aligning rocker arms when these heads are installed on any engine, but do require the use of hardened pushrods.
14 After setting the pushrod guideplates in place, the studs are hand threaded in, then t
15a Next up, installing the valvesprings. Using an old school
15b It uses the rocker studs as an anchor point, and compresses both springs on the cylinder at once, speeding things up. Its jack screw/ratcheting design means you only need one hand to use it, freeing the other up to drop the locks in place. This thing works great with the engine in the car too!
15b It uses the rocker studs as an anchor point, and compresses both springs on the cylin

16a With the valvesprings compressed, we placed the Comp machined 10-degree valve locks in place. The Comp locks are designed and machined with provisions for a lash cap to be installed.
16a With the valvesprings compressed, we placed the Comp machined 10-degree valve locks i
16b If necessary when setting up the rocker arms to get proper valvetrain geometry. A lash cap will also protect the tip of the valve stem from wear.
16b If necessary when setting up the rocker arms to get proper valvetrain geometry. A las
17 Here's how it'll look when done. This wasn't difficult at all, and will ensure that each cylinder has the tightest seal possible and make the most compression. Another benefit to lapping the valves is this also allows you to verify there are no burrs on the valve guides, which can cause a valve to hang up when the engine is running and create destruction and mechanical carnage in a freshly built engine.
17 Here's how it'll look when done. This wasn't difficult at all, and will ensure that ea

SOURCES
Comp Cams 3406 Democrat Road Memphis TN 38118 800-999-0853 www.compcams.com	Snap-On 877-762-7664 www.snapon.com
RHS 3416 Democrat Road Memphis TN 38118 877-776-4323 www.racingheadservice.com