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cam lob alignment

 
  #1  
Old 11-23-2007, 07:14 AM
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cam lob alignment

I am putting a 460 in my 55 F100 project.

I just had the engine rebuilt, keeping the same Comp 280h cam I had, which they say was ok.

We did new lifters, pushrods, rockers, and valves & springs, cause I went with roller rockers and guideplates. So the valvetrain is all new except for the cam.

As I am just about to re-assemble the sheet metal and I can see the lifters on the cam, and one set of lifters are not 100% on the cam lobes. Never seen anything like this before.. on one set of lifters (exhaust I think) they are only about 60% resting on the cam lobe, and the rest is not touching anything..

This rebuild was done by a professional engine shop, and they didn't mention any problems here.

Sam
 
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Old 11-23-2007, 08:58 AM
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I noticed the same thing on my 460 when I pulled the intake. Lifters looked like they were only sitting half on the cam lobes. I wondered too ..
 
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Old 11-23-2007, 09:48 AM
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Yes, they are supposed to be offset like that. I believe it is that way so the action of the cam causes the lifter to rotate in it's bore
 
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Old 11-23-2007, 09:53 AM
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Hmmm .. that might make sense .. wouldn't this cause the cam lobe to wear funny though (develop a "step"), since one half of it never sees the lifter load?
 
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Old 11-23-2007, 10:47 AM
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Thats why it rotates, for even wear. Also food for thought, a flat tappet lifter wouldn't/couldn't work if it was 100% centered on the lobe. Centered, the lifter would gouge out the lobe as it spun around, all that force would be concentrated on the very edge of the lifter at a very sharp angle and it would destroy itself.

Offset, the force is applied at a less intense angle over a greater distance along the edge of the lifter. . .

Still turkey buzzin', so don't quote me
 
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Old 11-23-2007, 05:00 PM
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When my cam is in on any of my 460 base motors the cam lobe is in the center of the bore.
did they forget the cam plate right behind the timing chain or shims since when you put on the timing chain it will pull the cam to the front of the motor

Dan
 
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Old 11-23-2007, 07:18 PM
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Originally Posted by daninline
When my cam is in on any of my 460 base motors the cam lobe is in the center of the bore.
did they forget the cam plate right behind the timing chain or shims since when you put on the timing chain it will pull the cam to the front of the motor

Dan
Only HALF of the lifters are not centered.. not all of them..
like I said before, I think these are the exhaust lifters..

then engine is currently 50 miles away at the body shop, so I'll have to go there to take a picture..

My assumption is an engine shop will assemble it correctly..

the only thing that remained on this engine was the cam, and the new timing chain. I had redone the timing chain about 50 miles/3 years ago, but didn't check the main or rod bearings..and developed a knock.. then it needed a bore job, but was 60 over already, so ended up using a different shortblock.

Sam
 
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Old 11-23-2007, 10:04 PM
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oh sorry about that but that is odd that have of then are off like that.
I'll take a look Sat at one of my 460's that has no top end on it to see what it looks like and if I can I'll snap a shot of it.

Dan
 
  #9  
Old 11-25-2007, 08:55 PM
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You are not the first to notice this and not the first to ask this question, but the guys are correct. The offset is there to make the lifters rotate so that the wear will be even on the lifter bottom and the lifter bore as well. This also causes the push rods to rotate minimizing their wear as well.
 
 
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