RE: [Chrysler300] 300H valve adjustment

["'John Grady' jkg@xxxxxxxxxxxxxxxxx [Chrysler300]" <Chrysler300@xxxxxxxxxxxxxxx>]

I do understand all you say, Mike, and agree with it, but I do question how
"they"  know what caused that valve to fail open, and burn head or valve
----as it did from your description, --- just applying common sense
.------If it cannot cool by normal time on the seat contact,  it will
overheat, and rapidly on to the bad sequel you describe , so that leaves
first cause as stuck valve (too tight in guide, it grows radially in high
heat too,(ref:  3 digits speed ), thus   locking it open in guide if too
tight,  or held open (when hot and expanded in length) by valve train / stem
axial expansion (adjustment) or float (bad springs)  . If it was on seat at
RPM,  it would cool normally like all the 300F's  at Daytona did, after many
many 140 MPH runs. 

 

How "unleaded gas" causes that to happen, in the physics sense, escapes me;
and unleaded gas is in all 8 cylinders, not just one.but as you say all were
somewhat damaged.  Or all had tight guides. Not criticizing or taking sides,
emperor's new clothes /Monday morning quarterback kind of stuff always goes
on around engine failures anyway .shop blames unleaded gas? They won't blame
" I /they put the guides too tight"    .you know. Same with that much blowby
at 10k miles . Were rings broken? (=detonation) ? If not, was that the fault
of unleaded gas too? Something REALLY wrong there. 

 

I restore old radios, another hobby. Much ado about old electrolytic
capacitors being able to be "reformed"(they go bad in storage) and how to do
that.  ; one guy commented he left them in full  moonlight for exactly 2
hours and 37 minutes, on white window sill, at 45 degrees to each other,
they reformed fine. Smile.

 

Yes , tappet gap impacts lift spec, as seen on .050 of lift is worth about
50 degrees duration (225 degrees at .050 is ~ a 275 cam at zero, or
advertised duration) , but all that huge variation in duration (50 degrees!)
is at under .050 lift..there is almost zero air flow into a valve open .050,
let alone less than that , from 275 to 225 spec variation, all is under
.050!. The real action is long after .050 off seat. Why spec at .050 is only
one that you can believe. So although academically true, net impact on
duration of even .010 less lift due to lash is all happening at a time when
valve is still essentially closed ; you took .010 off .450 at top  is more
like the way to think about it , now .440, about 2% . A clean air cleaner
matters more. And net power might go up even, in the sense of lower ET,  if
over cammed, needs more torque.  Interesting discussion, thanks for coming
back with real world data. Following through on this discussion while doing
your car is a very good thing,  for all of us to help understand this stuff.


 

You must know of the 62 HRM article about 300H (or 62 300 with legendary 405
H short ram motor-yes they did exist)---"HRM Special"  that set a 12.8 at
NHRA finals in 62? Faster ET than winning Pontiac, Chrysler guy was asleep
at wheel in final, Pontiac in 13's . That article and car impressed me so
much it is still as vivid in my mind as the day I read it new in 62..
Getting 12.8 out of  one of these huge heavy cars is simply unreal. As in
"bad"  15 sec 454 Chevells; 2.2 sec in front at 100 mph is about a mile. (ok
exaggeration)  And they started in 62 at almost 15 sec, like most of our
lettercars are, if that. Lots of tech detail in that article.

 

john

 

From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] 
Sent: Friday, May 09, 2014 2:54 PM
To: 'John Grady' jkg@xxxxxxxxxxxxxxxxx [Chrysler300]
Cc: Gary Nelson; bob marco
Subject: Re: [Chrysler300] 300H valve adjustment

 



Thanks for the note John. My unleaded gasoline valve failures were probably
not  ue to being too tight. One valve at least overheated apparently due to
inability to transfer heat to the head and in turn causing guide failure  or
so the  Portland head shop said. All valves showed signs of damage said to
be lack of lead. I also had the oversight of several  300 Club members when
my wife and I made an emergency detour to Ray Doern's back yard to pull the
heads. 

 

Lot of visitors!

 

 I still have the valve and the remains of the guide. The valve cover paint
was blistered and black from hot exhaust gas going out the  breather-very
serious blowby! 

 

The engine had less than 10,000 miles on a total rebuild by a top shop. I
had earlier been driving the car very fast and hard, into the low three
digits in fact. 

Consensus  at the time was the valves were damaged because of using unleaded
gasoline with unhardened seats.

 

My understanding from talking to some cam shops when I was looking for an
authentic 300H grind was that the valve lash also affects the valve timing.
As an engineer you can appreciate as the camshaft lobe rotates and runs out
of contact with the tappet, there will be a an angular difference between
say .015 tappet (valve) clearance and .025 clearance depending on how steep
the ramp is.

 I also agree that it's hard to imagine .010  will make a big difference-I
agree absolutely that too loose is far better than too tight. My problem is
though that I think I may have some valves which are too tight judging by
the exhaust note. The only way I'll know for sure is to check them. 

I also think its a great idea for me to check clearances cold, I am
undecided as to whether I'll try to set them hot. I'm inclined to try it
unless I can't see because of spatter on my goggles .

 

In reading trhough all my available pertinent literature, I see the Barnes
camshaft company wants the camshaft installed and valves set an additional
.005 (besides the ,026 they spec) initially before running it at 2500 rpm
for 20 minutes to seat the new tappets on the camshaft.

Best, MIke

    

 

On May 9, 2014, at 10:37 AM, 'John Grady' jkg@xxxxxxxxxxxxxxxxx
[Chrysler300] <Chrysler300@xxxxxxxxxxxxxxx> wrote:

 

  

I have often wondered about this question, as an engineer ; if the lift at
cam is .3 , a change of .003 on push rod side (.0045 at valve) is one part
in 100, 1 %---- I have a very hard time believing it matters at all to
anything, performance wise, .except one extremely critical thing . If in
the excessive zeal to "get it perfect", you set it too tight , exhaust valve
will not close tightly, (only when under high loads) which burns exhaust
valve or seat, and down you go--- big time . Head gets trashed . The stem
extends when hot ,why the exhaust setting is more, OEM . 

I went through this on an Onan generator with the equivalent of 1,000,000
miles (figured by hours) powering an isolated home, which lunched an exhaust
valve badly on propane (no lead) ; the symptom at first was lost power,
gradually reducing exhaust valve tappet clearance , which I thought was due
to adjustment not holding (manifested as loss of power and compression), so
I reset gap to factory (.017 cold) -three times,-- it had closed to like
.012; I had rebuilt engine some years prior (rings) and obsessed about
getting the tappet clearance EXACTLY RIGHT. Now it is on second (stellite)
valve, I added .003 (,020 cold) on purpose to be sure valve closes. These
are Onan numbers, not for Chrysler. Zero problems with this, last ten
years. Sounds like racing cam guy had same thoughts as I did-loose far
better ---by 1000X--- than tight. ; that Chrysler spec is a LOT of
clearance , big number for "HOT" ---and then, what is hot? Exhaust valve
stem at idle is ~ same temp as block, but really far hotter (????) at WOT ,
so setting it "hot" smacks of arbitrary BS, besides being a mess. While I
cannot remember details right now, I remember setting up a slant six cold
rather than hot with some added number I got somewhere. That number can be
figured out approximately by taking highest temp exhaust valve can ever be
(?1000F?) and length of valve stem times expansion rate of steel with temp ;
I would expect all push rod V8's not that far apart either, on this---
particularly if you add .003 . See brand X or aftermarket cam cold settings.

I do not understand how setting it hot at idle is more effective than
setting cold, if you have cold number.both are building in or allowing for
the expansion of exhaust valve stem when hot at WOT (.026?) , adding a
little more gets you out of all danger, even from a cold setting..but we
often do not have cold setting..but it is there , technically. As some
engines only show cold setting! Measure it cold, on this, after and before
setting it hot? Find out? 

Some will scream heresy at this, but as described ,this H already burned all
the exhaust valves once. I really doubt unleaded is the reason..more likely
valves were set too tight , someone going for perfection , (or used hot
numbers cold) and mixture lean at WOT (which can happen on carbs with
alcohol based fuels , need more fuel than real gas for given air flow
--which really ought to be rejetted for) ; I have many cars on unleaded,
have yet to encounter burned seats, except in alarmist magazine articles. . 

But I did destroy an exhaust valve over what must have been a too tight
setting, leading to no cooling of exhaust valve( it cools edge by
transferring heat into seat while tight on it (and by stem cooling) . By
the way, the cylinder side of that totally burned valve was still perfect ,
plain cast iron. And lead problem was supposed to be about recession, or
pounding into head, (which reduces tappet gap) ---not about burning. (or
"pounding into head", for that matter..why or how would lead possibly change
that?) With hydraulics, no impact at all to have receded valves, but might
lead to burning with solids if it takes up safety gap when hot .

So if you set it hot at idle, use Chrysler numbers, and do not worry if a
little loose ,,,but never tight.might even set loose. You might measure
cold first, before touching it , get that data for each valve, then do hot,
also measure and write down hot before setting , you will know difference it
changed due to idle temp--- within the .003 loose, to do it cold next time.

Just not as critical to idle or performance as made out to be, when running
along, IMHO..cannot be. But if you set it too tight while messing with it
, you are toast.

John 

PS agree 100% on distributors, they are in poor shape generally, after
storage , advance gets locked up and / or sticky . Often diaphragm is bad
which mity vac can find right away.

From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] 
Sent: Friday, May 09, 2014 11:06 AM
To: Listsaver 300 Club
Cc: Gary Nelson
Subject: [Chrysler300] 300H valve adjustment

I have been working gradually towards getting my 300H running as well as I
can. 

This forum has been a terrific help in many ways.

A big step was the professional restoration/rebuild of both carbs, which
followed the earlier massive and total restoration of the braking system,
including installation of the correct double diaphragm booster. (Booster
Dewey of Portland discovered that problem.) 

Recently, I had the distributor rebuilt which resolved my runaway idle
adjust problem and is generally a great improvement.

The next thing I am suspicious of is my valve settings. 

Unfortunately, the camshaft in the car is not the stock 300H camshaft, but
instead is one which a well respected 

racing engine shop in Illinois installed in 1982 because of a fear that the
engine would not be able to run on unleaded gasoline . (They were right in
a way because a few years later I had to have hardened seats installed on
the road.) It ostensibly lowers the compression ratio.

The camshaft is a Barnes Racing Cams Design no 275 (I have the spec sheets
for it) I do have a stock 300H camshaft which I eventually use to replace
it, but not this summer.

I had a well meaning friend stop by last year who was going to help me get
it running right,. He managed to destroy all the old car linkages by
bending them etc. and wanted to modify all sorts of things-in the process
though, we got into a valve adjustment exercise one might and he was
convinced the settings specified were wrong! 

So my next step is to set all the valve per the manufacturers specified
valve lash.

Chrysler 300H settings specified are .015 intake, .024 exh, set with engine
running.

Barnes F295 settings are .026 instake, .026 exh, set "hot"

I have no idea what settings I have which is why I want to verify it. I
suspect they may be stock 300H settings but the idle makes me think I have
some hot valves.

Question:

I do not think I have ever set these valves hot with the engine running as
specified in the shop manual.

I suspect that makes an awful mess.

Is it that important?

If you have set the valves hot and running, I would like to hear how it
went. 

Thanks, Mike Moore 

[Non-text portions of this message have been removed]

 










[Non-text portions of this message have been removed]



------------------------------------

To send a message to this group, send an email to:
Chrysler300@xxxxxxxxxxxxxxx

To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or
go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button

For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm

For archives go to http://www.forwardlook.net/300-archive/search.htm#querylangYahoo Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/Chrysler300/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/Chrysler300/join
    (Yahoo! ID required)

<*> To change settings via email:
    Chrysler300-digest@xxxxxxxxxxxxxxx 
    Chrysler300-fullfeatured@xxxxxxxxxxxxxxx

<*> To unsubscribe from this group, send an email to:
    Chrysler300-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo Groups is subject to:
    https://info.yahoo.com/legal/us/yahoo/utos/terms/