Hi and thanks for reading:
I bought a used cam from a 1989 L98 with 28k miles on its clock. I am going to install it in my LO3. The engine should really thank me for the increase from
Lift----------Duration------Lobe Seperation
.350 .384 179 194 109.0 (108/-112)
to
.415 .430 207 213 117.0 (116/-118)

Before I put it in though I have to ask a question to the deeply engine-wise among us.

The cam has an intersting wear pattern that
is visible on all lobes to some degree.

I'll do my best to describe it.

inoticed that there was some appreciable wear at the start of all the lobe ramps on one side . Looking at it,it looks like a short group of parallel grooves forming a oval shaped wear area about 1/8" long running along the path the roller rocker would move around the lobe.

I havent decided yet whether it is the "lift" side or the "closing" side. I'll have to think that one through. I do know that if the cam gear is to my right it is on the side of all the lobes facing me. It is a pretty even wear so i doubt it was bad lifter(s) with "bad' rollers or something like that.

Q1 Is this wear on the "lift" side or the "closing" side given the way i described holding the cam?

Q2 Is this a "normal" wear pattern?

Q3 If you can answer the previous two questions easily then you could probably help me understand what causes this kind of wear?

Q4 Is this cam safe for me to put in my engine an 83k mile LO3

Thanks in advance.
Mike

 

The cam turns clockwise, viewed from the front of the engine; so if you're looking along it from the cam gear end such that a lobe is pointed up, the right-hand side is the "opening" side. So it sounds like what you're describing is the "closing" side of the ramp.

In general, if all 16 lobes are worn the same, then there are several things you can infer. Either it's normal; or some external factor like running low of oil was the cause; or it was installed incorrectly (wrong mating parts or the like). It's highly unlikely that all 16 lifters or cam lobes were failing the same way, none of them particularly worse than the other, without any of them catastrophically destroyed. Usually when a cam fails, it's over with pretty quick. They wipe out in a big hurry, they don't take their time about it.

As far as the grooves: are they in the direction of being "around" the lobe, in the same orientation as the roller rolling around, or are they parallel to the length of the shaft? How deep are they? What do the lifters that used to be on that cam look like?

Cam failure almost always occurs at the tip of the lobes, where the forces are highest, before it occurs anywhere else. If the lobe tips are OK then the cam probably is re-usable. IMHO however, given the amount of work and expense you will incur making the swap, putting that cam in is a whole lot of maze with very little cheese at the end. If the engine is at all modified, or you intend to modify it in other ways, it's not enough cam (especially the lift).

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

ttt and thanks RB83L69

I am going to guess that you are correct and that the cam turns clockwise. So given that, then the first side of the lobe to contact the lifter is the "opening" side.

So this is wear at the base of the rocker lifting side of the cam lobe.

So what do yall think? is this cam going to probably work for me for 20k miles or so.

By 20k or so I may have to drop in a small block 400 to get that V8 satisfaction.

------------------
1988 Camaro Sport Coupe305TBI-4spdAOD-2.73open in "bought stock" condition. That'll change if it stays around here much longer mike.davis@firstunion.com