Packard Forum Index » V-8 (1955-56)

Thoughts and observations on valve train wear and adjustments:

1. Of the dozens of Packard V8s I've torn down, only one had terminal cam lobe and lifter wear. On most of the others, the cam and lifters could have been cleaned and re-used as per the bad old days shadetree rings-and-valve regrind rebuilds.

2. The Packard V8 valve train was designed with an acceptable assembled measurement of .050"-.210", or .160" of hydraulic lifter travel. No conceivable combination of normal wear and reconditioning would exceed this range of automatic compensation, if the work is done correctly.

3. "Stemming" is using a special micrometer to measure the distance from the valve spring retainer lower face to the head spring seat pocket. The measurements are compared to standard spec. Any over-length is removed by grinding the valve stem tip, thus adjusting the height of the valve stem to a to compensate for refacing of used valves, cutting used seats or new hard seats. This is a standard operation in any quality valve and head work and keeps the valve train length identical, spring pressure identical and both close to original design.

4. Rocker arm tips are one of the most serious wear points on a Packard V8. The tips should be refaced as a standard procedure on any Packard V8 rebuild. The amount of stock removed from the rocker tips will be compensated by that milled from the head gasket surface. Again, milling the head is a standard function of a valve job. Thus, the valve train length remains close to original design.

5. Most Packard V8 lifter noise is caused not by wear of the lifter face itself, but the cumulative loss of oil pressure from wear of rocker arms bores, lifter bores, cam, main and rod bearings and the oil pump itself.

thnx, jack vines

Quote:
<p>
Jack, do you have a special jig to reface the rocker tips since the radius on the tip must be maintained. On some of the worn tips I have, a considerable amount of material would have to be removed. This would probably remove the surface hardening which would accelerate follow-on tip wear.
</p>
<p>Craig</p>

Thanks Jack saying it with more authority and knowledge than I could have, that is what I wanted to convey. I've seen it done on every V8 engine rebuild I've observed.

EARLY 55 V8's not withstanding:

PV8 rocker arm valve stem tip wear is due to inadequate oil supply to the over head.

My engine with 34K original miles showed, relative to mileage, excessive wear at that point. Also excessive valve guide wear in the neighborhood of .006" to .009" stem to guide clearence. Rocker shaft and rocker arm bores showed no wear. The arm bore and shafts get plenty of oil. The rest of the overhead is near starving for oil.

Don't believe it????? Remove one valve cover and go for a drive. As fast u want to drive.

I don't doubt your observations, but suspect there was a lot of variability in individual engines in the oiling. I removed a valve cover out of curiousity on my late 56 Caribbean, at an idle I had oil spatter all over the inner fender in 1/2 minute. It's a 90,000 mile engine, hot idling oil pressure is about 40 psi, and at the filter inlet about 15 psi.

I've got a small mountain of rocker arms in the parts bin, some have a oil hole at the tip facing up, others don't. Never did see reference to this change in any TSB or Counsellor, and also didn't take notice of which style is on my own engine. Don't feel like pulling a rocker cover to find out, but I would like to know more about the two different styles.

Look at the SERVICE manual: Engine section, p 6, figure 13.
It's an oiling diagram. Look at the rocker arm area. It's very subtle but nonetheless diagramed in the illustration.
Also look at the left bank front intake valve in the diagram. iT shows oil flow across the top of the rocker arm altho i am guessing that part is artists license. It should show the oil ejaculating in a steady stream high enuf to clear the fender and land on the ground next to the car.

That particular figure is most likely from an early print 55 manual.

HOWEVER, the diagram is suspicious in that the oil gallery routing over the REAR most cam lobe is incorrect and is definately artists license.

The EARLY 55 rocker arm pee hole is covered somewhere but i don't remeber exactly where i saw it. Probably in one of the "Eng'ring Reports" that was published by SAE mentioned a few months ago. Seems to me tho that there is a Packard factory documentation of it.

However, this early 55 rocker arm pee hole issue was discussed quite a bit at AACA forum some 6 or 7 years ago. It mite have been BH who originaly brought it to my attention. Hopefully Brian can chime in here with more detail.

IIRC the rocker arms have a part number cast into them????
Do the pee hole rocker arms have a different number on them than those without pee hole.

What i do not know is if the early 55 SHAFTS had different oil hole locations drilled into them to accomodate the pee hole ARMS. I would certainly think so.

My 56 Exec shaft oils push rod socket while valve is CLOSED.
THAT'S 75% of the time. Oils ARM bore 100% of the time.

I'm surprised u only have 15psi at filter INlet. My aftermarket electric gauge taken at the filter inlet shows 15 to 25 psi at hot idle and 42-50 psi at speed. Ditto for the mechanical gauge i had connected to the filter inlet for several years until i swithched to electric aftermarket gauge.

The oem oil pressure tap at the back of the block is undisturbed as Exec uses idiot lite.

After valve job I drilled 3hree exhaust rocker ARMS on each side of engine for pushrod socket pee-hole. Drilled the SHAFT to accomodate peehole oil pressure when valve is OPEN (not closed). Drove a brass rod into oem push rod socket oiler hole of SHAFT.

Mine will send a stream of oil over the fender top and onto the ground next to my feet at idle.

ALL oil galleries are CLEAR including the 2wo main longitudinal galleries that feed the lifters. CLEAN. I checked them with a LIGHT and the short right angle gallery thru the head. rocker SHAFTS were perfectly cleaned inside from end to end.

All of that was done prior to the peehole modification. And prior to pee hole modification I ran the engine with oem oil routing with valve covers removed, hood removed and running 70-80 miles per hour for a 10 mile round trip. Barely any oil on anything except rocker shafts and on base of head around bottom of valve springs.

That's why i took it direclty into the shop and made the pee hole mod.