Our Cars: Cambelt Installation for the 308GTB QV

By Pete Vack

In which we tell you what we are doing (not how you should do it), why it must be done, parts sources, good and bad, and how much it costs.

Back together again. Yes, and running.

Cam Belt Installation
Our apologies for not continuing this earlier. Suffice to say that the Ferrari major tuneup project has been complete for some time now, and all is fine (thank goodness). We'll follow this article up with a spring cleanup and test ride when the weather returns to a more pleasant clime.

In the first part of our Cambelt article, we removed the cams from the car after checking the timing reference points. Presumably the cams are now sitting on the bench, the new parts ready to be installed and if you don't finish the job you will be in deep trouble.

Fortunately, the re-installation of the cams is not particularly difficult. Carefully place the cams in the bearings, again using a small pair of vicegrips to steady the cams as they are tightened down. The cam bearings are numbered and in my case the numbers on the bearings were facing the left side of the car. Use the cardboard shims in four outer bearings to keep the cams in alignment. Don't forget to cover the gaping holes in the head as you thread on the 10mm cam bearing nuts.

Timing Marks

Cams must be in perfect alignment to the notches in the bearing and cam. Getting this right takes time and patience.

The cam marks must be carefully aligned while the crank stays at the PMS 1-4 mark (firing stroke). As the PMS mark is on the left side of the engine and the only way to turn the engine is via the front pulley on the right side, there is much going back and forth from one side of the car to the other. Having an assistant here would save a lot of time. It's a wise idea to check the pulley dowels at this time. They should fit tightly but easily into the pulley and cam holes.

Once the cams are in perfect alignment with the PMS mark, tighten the cam bearings to prevent the cams from moving. Install the four pulleys and don't mix them up — check to see that the pulley belt guides are in the correct positions. Install the pulley bolts but don't tighten them yet. Align the pulley holes with the holes in the camshaft, but don't install the dowels yet.

PMS marks are difficult to see and must be cleaned. Mark read PMS 1-4 and must be perfectly in alignment with the pointer.

Note that the pulley washers have an indentation to provide a space for the dowels. Remember to replace the rubber O Rings on the pulley nuts. Tighten the pulley nuts just enough to allow the pulleys to stay in place but can still be moved by hand.

Belting Up
Ensure that the belt tensioner bearing is at it's minimum point—this can be done with a screwdriver at the "prying" points, and tighten. Installing the new belt is easy if you remember that it will not fit unless you allow the pulley to turn enough to line the pulley teeth with the belt teeth. Do not try to stretch or bend or twist the new belt. It will fit, but only once the belt and pulley teeth are aligned. Then it slips over the pulley quite easily. Tighten the cambolts finger tight. Loosen the belt tensioners and allow the tensioners to take up the slack. The pulleys will turn as the slack is taken up. Don't tighten the tensioners yet.

The pulley dowels should be cleaned and made to slip tightly but easily into the holes.

Find a hole on each cam which aligns with the pulley and camshaft. If you are very lucky, all four will have holes that line up. If not, you will have to remove the belt, re-adjust the pulley, re-install the belt, and check to see that you have a hole in alignment. Usually moving the belt one tooth will do the trick. This must be done to all four cams and it takes a while. It is extremely critical that this step is performed correctly.

When all four cams and pulleys have holes in alignment, remove the cam bolts, insert the dowels into the holes. They should tap in easily. Place the bolt washer with the indentation over the dowels — another important step. With the tensioners applying pressure to the new belts, loosen the cam bearings with the shims to allow the cams to turn. Turn the engine over twice in the proper direction of rotation (turning the crank pulley clockwise). This will allow the tensioner to take up the rest of the slack in the belt.

Ensure that the crank is now on TDC, PMS-14, firing stroke. Check the cam timing marks. If they are not in perfect alignment, go through the process again until all four cams are right on the money. Don't settle for less than perfect.

Make sure the pulley nut detent is over the dowel.

Tighten the tensioner bolts to 40 lbs. Tighten all four cambearings with shims and secure the camshaft from moving. Make double sure that the pulley bolt washers have the indentation over the dowels. If not, the washer will not be seated correctly and the bolt can't be properly torqued. Torque the pulley bolts to 70-75 lbs. Remove the cardboard shims, lubricate the cam bearings and camshaft lobes, and pour fresh oil in the head along the cams (again, an important step), and torque all cam bearing nuts (no specs here).

Double check all nuts and bolts!!! Once the cam covers are on, you will not want to remove them to check the bearing bolts for tightness or double check the cam timing marks. Why? Because new cam cover gaskets are very costly. And I needn't bother to tell you what will happen if the tensioners and pulley nuts are not all properly torqued. Do I?

Cam Cover Gaskets

Gaskets must be cut very carefully. Cut the distributor ends after installing the cam cover.

Ferrari's cam cover design is, frankly, pathetic. There are about 20 different mating surfaces which are prone to leaks. The $100 gasket set is thin paper and must be carefully trimmed to fit. 95% of Ferrari oil leaks will stem from the cam cover and end plates.

Therefore, make sure all mating surfaces are clean and free of oil or nicks. Carefully trim the gaskets around the cam seal housings — too much and they will leak around the cam seals and too little will have the same effect. I used RTV Copper at these points, but use it very, very sparingly, and only where the gaskets butt up to the cam seal housing. At the distributor end, don't trim the gaskets until the cam covers are installed. Then trim flush with the surface and install the end plates and distributor housing. Tighten the cam cover nuts in a cross pattern. Make sure that the "quicky" cam timing markers are installed and the timing marks can be viewed easily.

The rest is easy. The big moment will come soon.