I blew a head gasket on my 85, then did an
'in truck' rebuild....Honed the cyl, put in
new pistions, rings, timing chain, rod bearings,
etc & milled the head...

before I rebuilt it...the cylinder compression
(1-2-3) readings were eratic...with #4 under 80

now - 1,2,3 are all steady 150ish lbs
but #4 is 60-70lbs

(this is after 10k on rebuild- never checked after rebuild
truck seemed to be running a tad rough, but decent enough)

all the rings were installed properly..I tripple checked
to make sure were not installed backward...

my question?
is it possible the CAM could be flat spotted on #4 cyln?
seeing it is basically the SAME worst cylinder

ALSO....I added a teaspoon of oil into the #4, and
DID NOT get a higher reading...makes me believe it could
be the cam.

other points...
#1 truck was recently fully rebuilt when I bought at 150k
#2 truck now has 245k.....I rebuilt at 235
#3 truck got new head at 195k...overheated it/cracked it
and a professional mechanic installed that time,
but used the same valve train etc...
#4 there are no current/findable intake leaks on manifold

hoping my backyard rebuild wasn't a waste of my time...
thanks in advance for any other tips/answers

Jon

 

try adjusting the valves?

 

I think I did when I rebuilt...truck sat for 1
year after rebuild due to other issues

but yeah...thanks for reminder...

 

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Adjusting valves gave me 160lbs on all 4 cyl
thank you!

note--> what happened was...after that 'in truck' rebuild,
10,000 miles ago...it reblew a head gasket5k later...I didn't
mill the head 1st time (just gambled it would be ok)

well...they milled 9 thousands off (i think thats the number)
and I never readjusted the valves..was slightly dragging
on the lobes....because of the difference.

either way...Im happy my backyard rebuild is working out
fine...truck is smooth as silk now...with better power
and better gas mileage

anyone reccomend at cam that will help proformance
and & mileage???