Lee Ayrton

I'm tearing down a 1979 258. When I pulled the cam out I noticed that
some of the lobes have what looks like tiny fracture marks that run with
the rotation direction on the ramps up and down from the lobe. There may
even have been some flaking from the sides, but as the sides of the lobes
aren't machined it is difficult to say for sure.

Is this normal wear, or caused by collapsed lifters slapping the cam, or
or is this a failure?



--
Out for lunch. Be back on Monday.

Mike Romain

I tried to answer your email but it bounced back...

Anyway, that cam sounds toasted.

There 'are' different cams for those engines according to what emissions
package it has I believe. Something to do with the EGR flow I think.

I would recommend replacing it with new or rebuilt if such an animal
exists. You will likely need the casting number off the old one to get
the correct one.

I would also go for the high volume pump.

I have my old 258 sitting in my garage waiting for me to start building
it up nice. The engine I have in now only has 60K on it, so should be
good for a bit.

When I do mine, I am thinking on one step on the cam (maybe) with new
lifters for more low rpm torque, a better carb or a TBI unit (maybe), a
high volume pump, and headers.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Lee Ayrton wrote:
>
> I'm tearing down a 1979 258. When I pulled the cam out I noticed that
> some of the lobes have what looks like tiny fracture marks that run with
> the rotation direction on the ramps up and down from the lobe. There may
> even have been some flaking from the sides, but as the sides of the lobes
> aren't machined it is difficult to say for sure.
>
> Is this normal wear, or caused by collapsed lifters slapping the cam, or
> or is this a failure?
>
> --
> Out for lunch. Be back on Monday.

Lee Ayrton

On or about Tue, 29 Jul 2003, Mike Romain of romainm@sympatico.ca wrote:

> I tried to answer your email but it bounced back...

Grrrr. Given the amount of spam my ISP allows in, you'd think.... Oh,
nevermind. They're low-priced.


> Anyway, that cam sounds toasted.

I thought so too, and was sure of it when I was able to pull flakes off
the sides with a dental pick. Now I know what might have made those
little grooves in the mains. A new cam will be here tomorrow, with
lifters and pushrods (and bearings, seals, et cetera). To my surprise,
the local discount retail chain matched my mail-order cost from a large,
popular, Jeep-specialty outfit. More surprising, my favorite jobber
quoted me prices half-again higher and didn't list the cam at all.


> There 'are' different cams for those engines according to what emissions
> package it has I believe. Something to do with the EGR flow I think.

Perhaps AMC did that, but peeking over the counter at a data terminal it
looked like the part number is now the same for a couple of years either
way. For my curiousity, a cross-check showed it was no different for auto
trans v. standards. Of course, with AMC it might have just been a case of
whose shelf of parts was the low bid that month.

BTW, am I the last jeep owner in the US to find out that the connecting
rods have a date stamped under the bearing? Now I know it is a late
1979-early 1980 engine. (Rods manufactured 9/79).


> I would recommend replacing it with new or rebuilt if such an animal
> exists. You will likely need the casting number off the old one to get
> the correct one.
>
> I would also go for the high volume pump.

Thanks for that advice. I did order the HV pump. To my amusement, all
three sources I queried use the same Mell part number for their stock
number. Much less amusing wass the fact that those three quoted me prices
ranging from $88 to $160. Someone's packing in a little extra profit.


What do you like to use as an assembly lube? This engine will sit a few
weeks/few months before getting to run.



Thanks again.

A.H. MacIntosh aka USERNAME

Be sure to run-in the new cam properly. Most cam failures are a result of
improper run-in.

Careful with casting numbers, many times the same casting is used for
different grinds.

replace timing chain too (common sense).


"Lee Ayrton" <layrton@ntplx.net> wrote in message
news:Pine.GSO.4.43.0307291547150.10130-100000@sea.ntplx.net...
> On or about Tue, 29 Jul 2003, Mike Romain of romainm@sympatico.ca wrote:
>
> > I tried to answer your email but it bounced back...
>
> Grrrr. Given the amount of spam my ISP allows in, you'd think.... Oh,
> nevermind. They're low-priced.
>
>
> > Anyway, that cam sounds toasted.
>
> I thought so too, and was sure of it when I was able to pull flakes off
> the sides with a dental pick. Now I know what might have made those
> little grooves in the mains. A new cam will be here tomorrow, with
> lifters and pushrods (and bearings, seals, et cetera). To my surprise,
> the local discount retail chain matched my mail-order cost from a large,
> popular, Jeep-specialty outfit. More surprising, my favorite jobber
> quoted me prices half-again higher and didn't list the cam at all.
>
>
> > There 'are' different cams for those engines according to what emissions
> > package it has I believe. Something to do with the EGR flow I think.
>
> Perhaps AMC did that, but peeking over the counter at a data terminal it
> looked like the part number is now the same for a couple of years either
> way. For my curiousity, a cross-check showed it was no different for auto
> trans v. standards. Of course, with AMC it might have just been a case of
> whose shelf of parts was the low bid that month.
>
> BTW, am I the last jeep owner in the US to find out that the connecting
> rods have a date stamped under the bearing? Now I know it is a late
> 1979-early 1980 engine. (Rods manufactured 9/79).
>
>
> > I would recommend replacing it with new or rebuilt if such an animal
> > exists. You will likely need the casting number off the old one to get
> > the correct one.
> >
> > I would also go for the high volume pump.
>
> Thanks for that advice. I did order the HV pump. To my amusement, all
> three sources I queried use the same Mell part number for their stock
> number. Much less amusing wass the fact that those three quoted me prices
> ranging from $88 to $160. Someone's packing in a little extra profit.
>
>
> What do you like to use as an assembly lube? This engine will sit a few
> weeks/few months before getting to run.
>
>
>
> Thanks again.
>
>
>
>
>
>