Cam sensor runout

[Paul Lohr]

Has anyone checked the runout on their cam sensor at the gear? I checked mine because the cam sensor and oil pump gear would nearly bind when test assembled in the timing cover. The runout on my cam sensor is around .005". The oil pump shaft runout is right around .001" so I don't think the oil pump shaft is the issue.

Thanks for any help,
Paul Lohr

 

[87GN_70GS]

Do you mean end-play (up and down) or lateral (side-to-side, or radial: along the radius) runout?

 

[Paul Lohr]

Thanks for asking. Imagine mounting the cam sensor in a vise, parallel to the floor. The dial indicator was setup perpendicular to the cam sensor with the tip of the dial indicator on the smooth part of the gear. I rotated the gear and watched the dial indicator. I think this is a radial measurement.

 

[Paul Lohr]

So the cam sensor gear wobbles by .005". I have a carbureted 3.8L Buick engine with a distributor so I checked the runout on it. The distributor gear's runout is .006". While neither case is ideal, .005" of runout is probably normal. It would be interesting to measure the runout on a new cam sensor but I don't have one.

 

[Paul Lohr]

On a sidenote, could someone please tell me if the screw at the top of the cam sensor is reverse thread? Trying to remove it but so far it has not budged.

 

[RmvBfrFlght]

On a sidenote, could someone please tell me if the screw at the top of the cam sensor is reverse thread? Trying to remove it but so far it has not budged.

It is the standard right-hand thread. Right to tighten, left to loosen.

If you suspect that it has been lock-tited, a little heat directly on the screw head will soften it.

A trick that I've used many times is to tap on the end of the screwdriver as rotational force is applied. The downward force on the screw threads loosens them up. Don't know why it works, but it does.

RemoveBeforeFlight

 

[Paul Lohr]

You may have just saved me from having to replace the cam sensor. Thank you very much for that tip.

 

[NCTURBOS]

Paul... Spin that thing 3k+ rpm and watch what happens!!

Something else I've been seeing more & more of lately as well. I'm not too sure how well the pic will show up, but if you look close enough you'll see the other cracks as well. Very soon it would have been in about 5-pieces...


K.

 

[Paul Lohr]

Thank you for sharing this, my friend.

I see your point - it is a small amount of movement (.005") but the distributor gear has a lot of mass, now add some RPM.

On that broken cam sensor, does the casting look to be flawed?

I noticed there are two vertical parting lines (from casting) on my cam sensor. At least one of those cracks is in the same direction as these parting lines.

Thanks again,
Paul Lohr