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V8 Lifter vs Cam Lobe Overlap


garrycol

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Just put the heads back on my Rover V8 4.6 and putting the lifters, push rods and rockers etc back on.

I noticed that the lifters are slightly to the left of the cam lobes so the cam lobe does not run in the center of lifter. See pic - the lifter is offset to the left of the cam lobe.

20150816_1449051_zpssahoj2nh.jpg

At first I though the lifter was so far to the left that it was also picking up on the next cam lobe but it just clears (barely).

Is this correct or have I done something wrong - if so what?

Thanks

Garry

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That doesn't look right, but, how close is it to the other cam lobe? If it is slightly off set by a little bit then that is the bias to rotate the tappit and make the wear even across its face.

Unfortunately I can't tell you what the typical offset bias is on an engine.

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Thanks for the responses - confirms I needed to investigate.

Cam is new as is the thrust plate. Not sure what the reference to a blue box means.

So off came the timing cover and the timing gear.

The engine rebuild book says that the forward and back movement in the cam is supposed to be less than .35mm but in my case is about 2.5mm. The book doesnt say if the timing gear cog is to be on. My measurements are with it off. If it exceeds.35mm, the cam and or the thrust plate needs replacing but both mine are new.

I then took the camshaft out to do some measurements. As I have the old cam which is as new with no noticeable wear, I thought I would compare the two - except for the lobe profile both are exactly the same. So I put the old cam back in and put a couple of lifters back in and exactly the same issue - no difference between the two cams - so the old cam has been running in the engine block with the same offsets. I assume that when running the cam moves to a middle position.

Garry

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After careful consideration and a close review of the posted pics I have put the cam back in - the offset remains. With the cog and timing chain on there is no fore and aft movement in the cam.

On the issue of aftermarket parts, does this alignment of timing pulleys look close enough?

20150818_1859001_zpszemnxeac.jpg

The reason I ask is that the crank cog that came out of the engine has the timimg mark right under a tooth where the one above has it slightly to the right so i aligned them with the teeth in alignment meaning the marks are very slightly off.

20150818_1859561_zpsnjyyza0r.jpg

Garry

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