'78 318 rocker arm and pushrod issues

I have a 78 Dodge B200 van, 318, 4 bbl, with 352,000 miles on it. The
engine was rebuilt at 155K and seems to be running solid. Timing chain
was done about 20,000 miles ago. I've always run Castrol 20/50 with
changes, including Napa Gold filter, every 3k. I just switched to
Castrol "high milage" 20/50 this last oil change. (100mi ago)

My friend who works as a mechanic and has lots of years under his belt
does what work I need, as I need it. This last time he said he heard a
tapping under the valve cover on the driver's side. He figured rocker
arm and push rod (probably just one). Since he does the work for me
after hours in the shop, I have always done the part locating.

My questions are these, does anyone make an adjustable pushrod for my
application? Is it okay to replace just the "bad" rocker and pushrod?
Which valve cover gasket has the best leak resistance over time,
rubber or cork? Are there any special pitfalls to watch for in doing
this repair? What if I just leave it alone, what can happen? Is there
a SAFE way to clean crud from the lifters, if that is all that might
be causing the problem?

Thanks for whatever help you can offer!

-cadjak

 

Mopar performance used to sells an adjustable pushrod. Small block
pushrods and rockers wear a lot due to the poor geometery. And yes you
and replace just the offending rockers and push rods. a whole set of
pushrods is only $30 at and a whole set of standard rockers is onlt $80
at http://www.manciniracing.com/

These stock items can be bought at your local dealer or parts store also.

You may want to check your rocker shafts for wear also. Replace the
shafts if needed, the rockers and pushrods and your tick shopuld
disappear. If it don't it may need a lifter.
Dodgem

 

If it were MY engine (and I have a 430,000 mile 318 myself I'd
spring the $79.95 for a set of OEM-style but heavier stamped rocker arms
from Mopar Performance, and a set of new pushrods and lifters while I
was at it. No sense in being penny-wise and pound-foolish with an engine
that only has 100k miles on it since its last rebuild. If you decide to
replace the lifters, the job gets a little more complicated because the
intake has to come off (not enough room to 'fish' the lifters out
through the rocker covers like there is on a big-block Chrysler). But it
still is a pretty simple job.

As for valve cover gaskets, the Fel-Pro rubber-coated-fiber gaskets are
quite good. But I've had the best luck using Permatex "The Right Stuff"
gasket maker and *no* gasket at all. The older Chrysler engines have a
rough cast gasket surface on the head, and the permatex seems to seal it
the best. Fiber or worse yet cork gaskets always wind up leaking even if
you use a gasket sealant on them. One of the few true hard-part
"improvements" to these engines when they went to the Magnum-style heads
in '92 was valve cover sealing because they have a machined gasket
surface instead of rough cast.