Clewett Cam sensor install problem

[montauk]

I've drilled a hole in the cam cover after covering it with grease. There's maybe a mm between the back of the cover and the cam. I can't tap the hole even with a blind tap. The tip of any self tapping screw will simply hit the cam before it starts to thread. So attaching a screw and pulling on it isn't going to work.

I read about someone that tapped on one edge of the cover to force the other side up. I'm concerned about that given how close the cam is to the back of the cover.

I saw a video of guy that welded a bolt to the cam cover and then used a slide hammer to pull it off. I can do that but I'd rather not. Any other options?

[phelix]

https://forums.pelicanparts.com/porsche-911-technical-forum/1151611-removing-pressed-cam-box-plug.html

[Dr J]

I drilled a hole and used a slide hammer. As you can see by the pics, the engine was in the car.

[Jonny042]

Fire up the welder, I'd say.

[montauk]

Originally Posted by Dr J

I drilled a hole and used a slide hammer. As you can see by the pics, the engine was in the car.

You're a magician. I did a partial drop to get started on the ITB conversion. Then I decided to add the cam sensor so I pulled the engine out. I can't imagine doing that with the engine in the car. Fantastic work.

My problem with using the slide hammer like that is that I don't think there's but 1 mm between the back of the cam cover and front of the cam shaft. If I screw the slide hammer in, it will push again the cam.

[montauk]

It's out. I tried a few more holes trying to get a screw to get good purchase but no luck. Of course, I welded the wrong bolt to the cover so I had to make an adapter. You can in the photo why I was reluctant to weld. It's been 20 years since I've done it. It's ugly but it worked. I just gave my 3lb slide a couple of nudges and it slid right out.

[Jonny042]

Good job!

Curious - how did you find drilling the end of the cam? Seems to me it would be tough.

[montauk]

Originally Posted by Jonny042

Good job!

Curious - how did you find drilling the end of the cam? Seems to me it would be tough.

Thanks. I didn't drill it yet. I didn't realize that I don't have the correct 4.2mm drill bits. Hope to get them this week.

BTW, these Clewett products, trigger wheel and cam sensor, are very well made.

['78 SC]

The camshafts are cast iron. They drill and tap easily. The cuttings come off as coarse granules, not the spirals you would get with steel, so be prepared to capture them. A strong magnet or grease would probably work; I did mine with the cams out.

+1 on the Clewett products (and support).

BTW, check your ECU documentation so you know where to place the hole. Positioning it relative to TDC and the crank sensor is easy, just remember the crank spins twice per cam rotation. Also be sure to position the cam signal so it does not overlap the missing teeth on the crank sensor.

Here's the scope output from my ECU showing where the cam signal occurs relative to TDC and the crank sensor.

[montauk]

Thanks for posting that graph. BTW, no problem drilling the cam shafts. It's exactly as you described. I did notice the bit slowing down at one point and realized it was starting to bind in the aluminum collar. A quick clean and a bit of oil fixed that.

I needed a .5mm washer to get the correct depth from the top of the sensor body to the top of that bolt. I think I spent more time scrounging around looking for a washer that would work than I did drilling and tapping the hole.

Originally Posted by '78 SC

The camshafts are cast iron. They drill and tap easily. The cuttings come off as coarse granules, not the spirals you would get with steel, so be prepared to capture them. A strong magnet or grease would probably work; I did mine with the cams out.

+1 on the Clewett products (and support).

BTW, check your ECU documentation so you know where to place the hole. Positioning it relative to TDC and the crank sensor is easy, just remember the crank spins twice per cam rotation. Also be sure to position the cam signal so it does not overlap the missing teeth on the crank sensor.

Here's the scope output from my ECU showing where the cam signal occurs relative to TDC and the crank sensor.