Heads

First, you will want to remove the camshaft sprockets. Using the end yoke holder, or the make shift 2x4 and bolt thingy,  hold the sprockets in place and use a breaker bar to loosen the bolts (these things are tightened to 60 ft pounds so it will take some strength).

Second, you will remove the rocker assembly, there will be 10 bolts holding these on, you may want to leave the outer 4 bolts in the holes of the assembly because this thing will fly apart when you take it off . After removing the rocker assemblies you can remove the camshaft from the front bank ( head closest to the front of the car), the rear bank head has the connection point for the distributor so you will have to remove the four bolts holding it on. Remove the camshafts, clean them, oil them, wrap them in a towel, and place them in a plastic bag ( grocery bags work perfectly).

Next, you will need to take out the valves. I rented a valve spring compressor from Advance Auto for $60      ( It is the purchase price so you can either take it back and get your money back or you can keep it) Those screw and plier type compressor do not work to well. Place one end on the spring and the other on the flat side of the valve (be careful not to scratch the gasket surfaces), then squeeze the handle. If the spring doesn't compress that just means the keepers are froze so take a socket and a hammer and tap on the valve spring retainer until it pops loose. Use a set of needle nose pliers or a magnet to remove the keepers ( Do not lose the keepers they are small and expensive to replace, if you do 3sx.com may have them). Keep the spring, retainer, valve spring seat, valve, and keepers together in a sandwich bag and label them with the appropriate cylinder number and type (example-3 intake)  If you are replacing all or some of these parts then what ever parts you are keeping you will need to keep them organized. Then clean the heads thoroughly, you can use a good degreaser and a wash cloth, scrub brush, or a green scrubby pad. ( You can use a SOS pad or a wire brush but to not use them on the gasket surfaces or in the combustion chambers).

At this point you should have bare heads. If you wish to have a machine shop do all the work on the heads then you may do so at this point, if not I will guide you through this part.

The valve guides and and valve seats have to be pressed in so if you are going to change these you will need to have the head machined. The machine shop will press the old ones out re-cut the surfaces to a bigger size then have over-sized seats and guides pressed back in. This process only takes them a few hours but they can charge upwards of  $1000 for a set of 6G72 heads because they are less common.

At this point if you want to continue on your own then lets get to it.


I did a port and polish on my heads, if you do not know what that is I will tell ya. When the blocks and heads are originally cast they are cast in a sand mold and the sand leaves little dimples inside the intake and exhaust ports. A porting jobs refers to removing the burrs and dimples from the ports that are left behind from these sand castings with sandpaper or sanding rolls and a drill. Sand paper offers a smoother surface because you can start with 80 grit and work your way down to 220 grit, however, you will do a lot of sanding and your hands will get tired. Sanding rolls come in two different types, the tapered roll and the straight roll. Straight rolls will help you do the floor, roof, and sides of the port (fortunately for us the port is round so there is no floor, sides, roof, or floor) and the tapered rolls will help you get into the tighter spots. One thing I like about the SOHC heads is the ports have a pretty straight design there isn't much for bended areas and there isn't any major obstructions. The rolls come with a threaded mandrel to put in a drill. Thread the roll onto the mandrel and in a circular motion start sanding the rough spots off of the ports. All we are trying to accomplish is a smooth surface so do not remove a lot of material unless you are very experienced and you know what you are doing. If you have a Dremel tool you can use that to get into the even smaller areas. The rolls come in 80 grit and 120 grit so once you are done you can use 220 grit sand paper and get an even smoother surface. Once you are satisfied with the smoothness you can polish it if you wish, a polishing compound can be used but you will need to make sure all remnants of the compound is removed, there are also polishing stones you can use, personally I do not see the point in doing all the work to make it pretty because you wont see it and within a month your ports will be dirty again, as long as it is smooth your air will flow better and the carbon wont have rough areas to stick to. However, if you are building a racer then you will benefit more from the full polish but I would let a professional do this because they will actually straighten out your port so you get optimal air flow, there is a science to perfect airflow and this is beyond the capabilities of an amateur do-it-yourself 'er. The porting job I did is a mild one and I will still get extra cfm's for it and a few more horses but it isn't the full polish.

I used this grinding stone to remove all of the old carbon build-up from the intake and exhaust ports.

This is what it looks like when all the carbon is removed

First, I sanded the port with 80 grit sandpaper

If you decide to do port matching then you will need to do some research on this process because without practice it is a difficult procedure to not mess up and if you do it wrong then you will mess up your head, so if you do not have experience then do not attempt it. However, we will be doing a minor version of this with out intake manifold and intake plenum ( there is no sense to do a port job without doing it to the intake manifold and plenum. Besides the gasket for the intake already matches up with the ports pretty good so we wont need to do port matching we will just do a polish on the manifold and plenum.

The next step I will go over is Valve Lapping. Valve Lapping is the process of making the valve and valve seat have a nice even seal. Whether you are re-using the old valves of using new ones it is a good idea to do this process, especially if they are new. We will start by taking our valve lapping tool ( which is nothing more than a wooden dowel with suction cups on both ends) and our lapping compound ( $5 at Advance Auto) and set them near your work area. Take a valve and place some lapping compound around the edge and put some clean oil around the valve stem. Turn your head upside down (elevated by 2 rolls of duct tape or whatever you have laying around) and carefully push the valve into the appropriate valve guide. Push the suction cup firmly onto the valve and with a twisting motion twist it back and forth until it sounds like it isn't grinding anymore and lift the valve up and tap it on the valve seat 3 times then repeat the process, each valve can take up to 5 minutes each so be patient. If you mess up here you will have to disassemble the head when your compression check doesn't give you the proper results. You should see a nice even line all the way around the valve and seat that was ground out by the lapping process the line doesn't have to be very wide, only a few millimeters.

Now it is time to do the valve stem seals, you can remove them by gripping them with pliers then twist and pull. Push the new ones on by hand until you can't anymore and the use a socket and a hammer to tap it on all the way.

Now it is time to reassemble the valves (remember to put them back on in their original places, unless they are all new)  If you want to check for leaks now would be a good time. If you have the old spark plugs you can put those back in and then fill all six combustion chambers with oil and let it set for a few minutes, use a flash light to look into the intake and exhaust ports and see if there is any oil seeping in to the ports, you can even wrap a clean, dry paper towel around your finger and wipe around inside to see if there is anything wet on the towel, if there is then you have to continue the process on the leaking valve. If there are no leaks then you are done. If it leaks oil than it will leak air, but if there is no leak then that means no air leaks, and the reason you use oil is because motor oil is designed to seep into every nook and cranny.

If you had any lifter tick then you will need to replace all of the lifters because it is almost impossible to tell  which one it is, but no worry they are only a few dollars a piece from partsdinosaur.com. These will come unbled so you will have to bleed them. The manual talks about a "Hydraulic Lifter Leak Down Tester" but I was unable to find one online or in any auto parts, auto supply, or tool store so if you can find one I am sure they are expensive. I talked to someone online that said you do not need one if you are replacing them with new ones. The tool is only needed to test old ones to make sure they are still good. You will need a bleeder needle but a paper clip should do sufficiently. You will also need some clean diesel fuel. Pour the diesel fuel into a metal or glass bowl (Styrofoam bowls will disintegrate)  and hold the lifter with the plunger upright, press the plunger all the way down and insert the paper clip into the hole to press the ball valve down so that it will bleed the air out. You will need to place them in something so that the diesel fuel doesn't run out and the lifter fills back up with air, an old ice tray will work. There are special little clips that you can use to hold the lifters inside the rocker arms during reassembly but I was unable to find them so I used little pieces of duct tape.

Put some reassembly lube on the camshaft bearing and caps, put the new camshaft oil seals on the camshafts, then put the camshafts back on the head ( you do not have to worry about putting them on backwards because there is only one way to put them back on).

If you didn't listen to my suggestion with the rocker assembly and it flew apart the manual will show you how to put it back together. Reassemble the rocker shafts and bolt them back on to the heads, but before you tighten them all the way down leave them loose enough to remove the duct tape. Then tighten them down to the specified torque.


If you are still unclear about the procedures you can watch the videos on Youtube.com for more clarification, just search for "Valve Lapping", "Port and Polish", and "Port Matching".