I was able to make some more progress on this project over the holiday weekend, but an unannounced visit from the "outlaws" limited my time in the shop somewhat. Oh well, I made good progress after they left, but I had been hoping to have the engine on the dyno for some cam timing variation tests. That will have to wait until this coming weekend I guess.
First project this weekend was to get the Cloyes timing gear drilled for different cam timing locations. I also wanted to take advantage of the solid center of this gear to drill it for targets for the cam sensor that I had envisioned going into the removable front plate of the timing cover. This turned out to be more complicated than I had imagined. First, I wanted to make sure that the cam target passed by the sensor location in the cover plate 135 degrees before TDC on the #1 firing stroke. This way, the next crank sensor pulse would be the #1 cylinder pulse (the crank sensor on most EFI systems triggers well before top dead center in order to allow the EFI computer to add ignition advance to the spark pulse). This basically meant that since any change in cam timing required a re-position of the top timing gear, I would need to have seven different positions for the cam sensor, one for each position of the cam pin, in order to maintain the 135 degree lead angle.
After I figured all that out, the next complexity turned out to be the water pumps. Surprisingly enough, I found two stock water pumps with different shapes, and both of these were different than the shape of an Edelbrock pump. And of course with my water pump adapters and the CVR electric pump, there was a fourth combination. The difficulty was trying to figure out where to position the cam sensor so that no matter what water pump was used, it would still fit. The sensor sticks out somewhat from the timing cover plate, making fitment a little complex. Finally I figured out a good place for the sensor, and wrote the program to machine the upper Cloyes timing gear. Here's a picture of the Cloyes timing set after the top gear has been machined, and then another picture with the top gear installed on my 428CJ:
The bolt with the nut behind it, shown screwed into the top gear in both photos, is the target for the cam sensor. I used a Cherry gs1001 cam sensor for this mockup, which has its own magnet and will turn on when the front of the sensor is close to any steel or iron object. Each hole for the cam sensor is marked with the corresponding timing mark for the pin that goes into the cam. So for example, if you are timing the cam so that it is 2 degrees advanced, the pin for the cam goes in the +2 marked hole, and the cam sensor target screws into the corresponding +2 hole in the outer ring of the gear. Once the removable cover is put in place on the timing cover, the sensor should point right at the cam target at 135 degrees before top dead center of #1 on the firing stroke. Here's a picture of the front of the engine with the timing cover plate installed, plus the Edelbrock water pump, the harmonic balancer, and the factory timing pointer:
Just fits LOL! The Edelbrock pump is the tightest setup, so I think this setup will work with any mechanical water pump. I'm not sure about some of the other electric pumps out there, like for example a Meziere pump, but I'm hoping there will be enough room with those setups also.
One thing I discovered when messing around with this installation was that the cam installed in this engine (Comp 294S) had a pin hole in the cam that was much smaller than the hole in the Comp roller cam that I had originally measured. The pin hole in the roller cam measured right at 0.3125", exactly 5/16", but the cam installed in the 428CJ had a pin hole that measured 0.309"! This is the same kind of variation that I saw in the different timing gears that I had measured. After test fitting the timing cover and removing and replacing the top gear through the center opening a few times it had become clear that I needed a slip fit of the pin into the timing gear and the cam; a press fit wouldn't allow the top gear to come off. In order to get the top gear off you need to pull the pin first, and then pull the gear forward off the nose of the cam. The conclusion is that to make this setup functional for changing the cam timing, a slip fit of the cam pin is mandatory, and because of the variation in pin holes in the cam, the pin that came with the cam is the one that needs to be used.
After I got the Cloyes setup dialed in I put the original Rollmaster set back in, with the modified top gear, and started to get the front of the engine together. I had decided to try out the 351C front seal for this installation, and when I got to the installation of the crank sleeve, it became apparent that it would have to be machined to work with the front-installed 351C seal, because the sealing surface of the sleeve wasn't long enough. Just another delay, and that's where I'm stuck at the moment. I expect to have the crank sleeve machined and the engine all the way back together later this week. So, again barring no unforeseen problems (or visits from the outlaws LOL!), I should be able to test this setup on the dyno next weekend. Should be fun...
