Custom Automotive Timing Cover

I’m coming down the stretch on my induction system project. This is a timing cover to be used with the project described here:

http://forums.thehomefoundry.org/index.php?threads/automotive-intake-manifold-–-boss-302-independent-runner.1692/

Because the intake manifold runners cover the distributor on the engine block, back in the day (late 1960s), for a small number of experimental and racing intake manifolds, Ford engineers made timing covers that relocated the distributor about 4” forward of the stock location. A camshaft extension was then incorporated to drive the relocated distributor.

So with that, I started reverse engineering all the interface dimensions and began the modeling and CAM programming. I must say, there’s a lot more to this part than initially meets the eye because it interfaces with just about every working system of the engine. It touches the crank/reciprocating assembly via the oil seal, the valve train via housing the timing chain and camshaft drive sprocket, cam/distributor gear interface, the mechanical fuel pump via the eccentric mounted on the camshaft/timing sprocket, and of course the cooling system via the mounted water pump. That made for a lot of engine interface dimensions and a boat load of features on the part that needed to be accurately located.

The part is about 4” deep. The stock timing covers were just under 2” deep which was rather convenient since I only have 2” thick foam board and the features were such that it needed to be split anyway in order to be able to machine all the features on a 3-axis machine. So the two major pieces were the upper and lower sections, both of which had front and backside machining.

The lower section had the most features. It was almost all 2.5D machining except for the webbed area around the crank seal which was 3D.



The upper section was all 2.5D machining.



I glued the upper and lower sections together.



The feature count was really getting up there so I decided to separately make and hand place a few of the bosses and the distributor mounting features because they were in off-planes and it just wasn’t worth all the additional programming and machine time. With all the programming, I already had all the geometry available to cut the interface surfaces on the distributor mounting features which was a big time saver and greatly aided in accurate positioning of these features.



I was able to cut most of the oil pan seal undercut with a lead in/out move but had to cut the blind hole for the oil pan seal gasket tang in the corner with a razor knife.



With a little detailing, I was happy with how this pattern turned out.



Since I had all the geometry for the part I used it to make the gating, attaching everywhere there was a solid boss on the pattern, since they were the thicker areas to feed the part.



I attached it along with a couple chunks of MDF for handling and using the screws as feet for drying.



I’ll attach the rest of the gating and sprue when the coating dries and am molding the part.

Best,
Kelly

 

This is a pretty complex part...I know Kelly can pull it off, but will he get it on the first go??
Place your bets folks
Should I start a poll ??? Lol...

 

......this is never going to work.....

Best,
Kelly

 

Ready to go. Sub zero F lows. Hoping for a little better weather this weekend. The part is just a little too big to fit my 5gal size flasks and will need to go in the 30gal. That’s a PITA when the pavement isn’t dry because I cant demold by dumping on the ground. Same thing with the quench tank. A 5 gal bucket wont due so I need to use the pickle crock….another PITA.



Best,
Kelly

 

Well it was 0F this morning but no wind. I saw clean bare pavement on my driveway and got after it.

Charged the crucible, loaded it into the furnace (inside my shop), and flipped the switch. Then commenced to packing the mold and staging the pour.



About 45 minutes later the deed was done.



....and foam became metal. Here’s how it came out of the sand.



…..and then degated and light media blast.



It came out realllllly nice!



Best,
Kelly

 

Amazing as always!

Jeff

 

Don't know if anyone noticed it on the raw casting photo but I've been burying the patterns deeper and using a longer sprue when possible. This part was 28" from the top of the cup to the bottom of the pattern and the pattern itself about 12" tall. I had done so on previous parts a ways back to get more head pressure to help fill thin walls but one of the things I noticed when using the longer sprue was I always had a very tranquil pour with no flame or black smoke in the cup.........just a cup full of shiny metal. Part of it is the pouring cup but the rest is achieving good head pressure early in the pour before the metal front gets to the pattern. I've also been using very low density foam in the sprue so that stuff evaporates very quickly and (near) simultaneously delivers metal to all the pattern gates. -Just a tidbit.

Here's the YouTube video on this project.



Best,
Kelly

 

I do enjoy casting but my motivation is usually making a functioning machine part, often engine parts. It's very satisfying when you have a need to just imagine it then make it. I do have interest in casting other metals and ornamental art work.........but all my artwork ends up looking like machine parts I happen to need.

Best,
Kelly

 

The answer to the shrink is disappointingly simple. When the CAD/CAM model is complete, it's one stroke of the scaling key after selecting the entire model then increasing it's size by 1.3%. If it is a manual process, I just increase the dimension by same (multiply by 1.013).

For the details, it depends but on a part like this that has so many interface dimensions with the engine components, I start with them. Prints for some of that information are either available or known to me from past projects and I have to do layout work and measurement to reverse engineer the rest. These would be bolt hole locations, cam and crank center line location, etc, then place bosses around these locations and connect the dots. For something like the outline shape of the water pump mount, I photocopied a gasket, imported and scaled it to the bolt hole locations that were known to me, and then used that geometry to generate tool paths for those profiles. This is done at the different tool path heights/depths as features require.

95% of that pattern was 2.5D machining cut with just two tools; a .25D x 2"CH spiral double flute end mill and a ball nose of the same dimension. The tool path can be offset in the program to cut .125 (1/2D) wider for the end mill and the ball nose does the finish and fillets at the bottom of the cuts.

The upper and lower section were the two major pieces. Both were machined front & back. Each of the 4 sides had a run time between 8 and 15 minutes. Foam can be cut at very high feed/speed rates.

Best,
Kelly

 

I'm not quite there with Fusion on either the CAD or CAM front. I'm using CamBam. I also have a trial version of Mach 3 but every pattern I've actually cut thus far has been CB.

Best,
Kelly

 

Machined up the timing cover.



Here it is mounted on a tall deck block.



The intake goes on a lower 8.2 deck block but I have this one handy for show and tell.

Best,
Kelly