Getting messy with spray paint: Finishing the instrument housings

Back in March we posted the crazy task of micro welding new threaded studs to our instrument casings. For those who missed it here is the link:

http://dino246blog.blogspot.ca/2012/03/crazy-task-4-micro-welding-most-obscure.html

Now that the casings are back from plating we decided to finish them off in preparation for their assembly. First task was to mask off with great care the surfaces we wanted to leave alone. Then a very light blasting with glass removed any residue and plating from the threaded stud and other hardware on the case. Next came painting the inside of the unit using a flat white paint (this is to most evenly reflect the light bulb that illuminates the instrument at night). To do this we found that the best way was to put on a latex glove and hold the instrument when painting it. Sure we got paint all over our hands but it was the most efficient way to articulate the part as needed in order to paint it well. Last came the delicate process of unmasking everything. From start to finish a crazy task for a part that lives deep in the dash but we feel the results are worth the effort.

More shim talk: Images of the blueprinted head

Yesterday we made an important point that is worth repeating regarding the shims that are used to set the valve lash on a Ferrari Dino engine:

Thinner than about 3.40 mm and the cam can clip the edge of the cam bucket rather than ride on the cam.

Thicker than about 4.00 mm and the weight of the shim starts to play a role as it becomes heavy enough to move between the bucket and the cam with the possibility of the shim dislocating at high engine RPM's that could result in engine failure

We did a lot of research on the correct shim thicknesses before machining and found that if you are going to do a job like this you need to find someone who speaks the language. Lucky for us David F. at Ferrari Service of Bedford is so knowledgeable that he is fluent in Ferrari (www.fluentinferrari.com).

David outlined the risks of going too thick or thin and the closeup photos below help illustrate this where it can be clearly seen that if a shim is too thin it can cause the valve lobe to clip the edge of the shim bucket.  As for going too thick, it is hard to illustrate so lets just take David's word for it. Trust me this guy knows his stuff and we thank him for sharing his knowledge with us.

Now for some finished shots of the heads with all new solid stainless steel valves (to replace the fracture prone sodium filled Ferrari parts), beryllium valve seats, and freshly skimmed deck surface. Some readers will note that the block was not skimmed where the head gasket mates to it. Again following David's advice, once we determined that it was perfectly flat, we left it alone as machining it would improve nothing and only introduce unnecessary risk.

Lastly some may remember images of the butchered head plug where an SAE plug was forced into a Metric hole. Well Gord B. acquired a special tapered tap, worked his magic and here is the result: a perfectly installed plug. 

The right shim: Blueprinting the valve train

Today we will discuss the valve train of the engine and the importance of fitting the correct shims. To start we'll have a quick anatomy of the system so that everyone is on the same page regarding names of parts. In the photo below the labelled parts are as follows (with explanations):

 

A - Cam lobe - Rotates to push the cam opened and closed

B - Valve - Opens and closes to allow fuel to enter or exhaust to exit the engine

C - Valve Seat - The surface the valve closes on

D - Shim - Disc of metal available in calibrated thicknesses

E - Valve guide - Tube that the stem of the valve rides in

F - Shim Bucket - Holder for the shim 

G - Valve spring - Closes the valve as the cam turns

Now with the pieces identified we can move on to what happens when a full re-build of the heads is done. This procedure includes:

- New valves

- New valve seats

- New valve springs and retainers

- New valve guides 

- Pressure testing of heads 

- Cutting of seats to seal with valves

- Full checking of measurements with machining as needed

- Setting of valve clearances

It is the final point that is for discussion here and the following diagram should illustrate things a bit better: 

Valve or 'tappet' clearances are required because the solid valve system requires a small amount of play between the cam and the shim when cold because if there were no space, when the engine heats up, the expansion of all of the metal parts in the valve train would cause a valve to stay open just a little bit reducing engine efficiency and possibly damaging the valve. There are many designs to adjust this clearance and Ferrari's use metal discs called shims that go on top of the bucket setting the distance to the cam lobe. As the valve train wears the bucket gets closer and closer to the cam requiring a thinner and thinner shim to stay within spec. 

The Ferrari parts book shows shims available between 3.25 mm to 4.90 mm spaced in tiny increments of about .02 mm. Despite this broad assortment you cannot use them all and, although conventional wisdom would dictate to place the thickest shim possible (to offer the most future adjustment), this too is also problematic. The fact is that shim thickness is limited in the following way:

Thinner than about 3.40 mm and the cam can clip the edge of the cam bucket rather than ride on the cam.

Thicker than about 4.00 mm and the weight of the shim starts to play a role as it becomes heavy enough to move between the bucket and the cam with the possibility of the shim dislocating at high engine RPM's that could result in engine failure

When everything is new it is essential to blueprint (ie. machine to spec) the components of the head so that the shims used are as close to about 4.00 mm as possible. Too thick and you run the risk of a shim moving in the engine and any thinner and you are taking adjustment range away from the engine in the future as it wears. Very few engine builders take the time to get this step right and even fewer use the correct tools and techniques to achieve the desired result. 

Essentially there are 2 adjustments to be made:

If the shims are too thin: The tip of the valve stem needs to be trimmed in a special machine.

If the shims are too thick: The valve seats need to be cut to push the whole valve deeper into the head and closer to the cam lobe. Some engine builders will recommend cutting the valve head (often because they do not have the proper machine cut the seat) but this is bad practice because you want to preserve as much material on the valve as possible to maintain its strength and ability to dissipate heat and stress. 

In our case engine guru Gord Bush from GB Performance was entrusted to machine and assemble our heads. His meticulous attention to detail and well equipped shop ensured that, in the end, all of our shims were between 3.95-4.00 mm. Gord really took the time to do a good job and remarked that the Dino was his very favorite car. Who were we to argue :)

A powerful paint job: Finishing the engine block

After machining and cleaning the engine block it was time to paint it. Dino engines are made from cast iron and to keep them from rusting they received a gloss black painting at the factory. The first step in any paint project is to ensure that the surface is prepared as well as possible. To achieve this we masked off anywhere dust or dirt can get in, cleaned the block with a wire wheel, and then used pre-paint solvent to remove any oils or deposits. It is at this stage that taking your time is CRITICAL because if the surface is not clean then the paint will peel down the road.

Once cleaned the block was treated to two thin coats of high temperature engine enamel. We like using paints made by VHT in a spray can but any high quality engine paint will do. With the block painted we are now approaching the time for assembly.

Custom torque plate ensures a perfect round: The engine honing

After sonic and x-ray testing the block for structural perfection it came time to check all critical dimensions and machine as necessary in preparation for assembly. It is here that an expert engine builder chimed in and stressed the importance of using a torque plate when honing the cylinders.

For the uninitiated, a torque plate mimics the effect of a head that is torqued to the engine block. The stresses imposed by the head studs on the block (when under load) actually distorts the shape of the cylinders a minute amount. If the engine were machined without it then the cylinders would be perfectly round until the head were torqued on when they would change in shape. Machining with the plate ensures that the cylinders stay round when the heads are installed. This frees up horsepower and ensures proper and even wear of the pistons and rings.

Many engine builders skip this step but it is important if you are to have the best possible result. After honing the block was ready for a final cleaning and then paint. A special thanks goes out to Paul Newman for his guidance with this part of the project.

Dino and the crew thanks you

Today Dino and most of the restoration crew took part in the Toronto Humane Society 'Paws in the Park' fundraiser. Contributions collected from family, friends, and I am proud to say blog followers, allowed us to raise more money than any other participant.

We would like to extend our sincere thanks to those who follow our progress and especially to those who put forward a donation to our efforts. As a thank you, starting tomorrow we will start posting a daily string of updates including long awaited images and stories of the work being done on the body and drive train.

Dino needs your help!

Many of our faithful readers will have noticed that our posts have been rather thin over the past 6 weeks or so. The truth is that the Dino has been temporarily on hold as our attention has been turned to our family that is mourning the loss of one of its close members.  

My father in-law, Annetta’s dad, and our dog Dino’s best buddy Richard passed away suddenly and unexpectedly at the end of July shelving the restoration for a few weeks. Our trip to Concorso Italiano last month was to uphold a promise we had made to Richard that we would show Luigi there and it was with heavy hearts that we undertook the journey. Understandably it was very special to drive across the lawn and accept a prize in his honor.

As we go through the process of healing there is one special event that we will be taking part in and it is to the followers of our blog that we would like to make a humble request. Next week is the Toronto Humane Society ‘Paws In The Park’ event to raise funds and awareness for the centre. Not only was it Richard’s favorite charity but it was also his favorite Father-daughter event that he would take part in with Annetta. The last time it ran was in 2005 so he was thrilled to enter this year with Dino as the event was resurrected for 2012. Sadly he will never get the chance to walk this year so Annetta and I are making a special effort to raise as much money as we can in remembrance to Richard.  

Below there are 2 links: 

-          One is the official donation page where credit card donations can be made securely online

-          The other is a PayPal link we have created so those with PayPal accounts can donate. This money will be pooled together and donated as a lump sum on the morning of the event on September 23^rd.  

If you are a follower of our website and blog and derive entertainment and education from it we respectfully request that you show your appreciation by supporting us in this cause.  

Many thanks for you attention and please check back next week after the walk for comprehensive updates on the body and engine filled with photos, tips, and tricks to help in your present or future restoration project.

Link to donation page:


http://torontohumanesociety.akaraisin.com/PawsinthePark2012/dino246


PayPal Link:

https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=862M4BFWB2E96

Of course this post would not be complete without some photos of our Dino :)