Re: {Chrysler 300} valve lash adjustment hemi

agree Henry , but exhaust has to be closed for a significant time rotationally after tdc or you will burn valve / lose power . Remember cam turns half as fast as piston crank , and cam degrees are not crankshaft degrees . So valve activity has not commenced even just after TDC ignition especially given slower rotation of cam , the ramps are a small part of total exhaust event . but I am open to learn ..

At least as I understand it exhaust would open near bottom of power stroke , exhaust pushed out by pressure and then by rising piston on exhaust stroke . with some overlap /,early opening at bdc. yes. Maybe I will look at cam card .

Doing things without understanding the why is just a road to disaster â€œ cuz Iâ€™m the mommyâ€? type stuff . No doubt it works , despite no obvious explanation... may just do it that way ..
thanks for chiming in !

John

Sent from my iPhone not by choice

On 13 Feb 2021, at 11:44 am, RICK AND DEBBIE CLAPHAM <rixpac@xxxxxxx> wrote:

More brain damage, how about industrial 413 engines and marine reverse rotation engines. Fun to think about. But for your application your decal works on A, B, RB and RB Hemiâ€¦ Rick

Sent from Mail for Windows 10

From: Henry Schleimer
Sent: Saturday, February 13, 2021 8:09 AM
Cc: 'Chrysler 300 Club International'
Subject: RE: {Chrysler 300} valve lash adjustment hemi

John

This is a good question because it isnâ€™t as simple as one would think. Lash has to be set with the lifter on the cam base circle. For example, at TDC on the firing stroke, the exhaust valve â€œis getting readyâ€? to open soon. So, depending on how the cam is ground, some of the â€œslackâ€? may already be taken up.

How do I know? I looked at the 57 Service Manual lists which tappets are on the low side at two! positions (Cly 1 & 6 firing). Too easy! Silly me set the lash that way on my 300C when rebuilding it years ago. However, before I finally put the valve covers on, I thought I should do a check and found the gaps were way off. Maybe the Manualâ€™s advice was ok for a New Yorker cam but not for a 300C cam which has more duration. The adjustment chart below is probably right â€“ havenâ€™t checked it. If you want to check the exact mid point on the base of the cam, split the angles between valve close and open from the specs.

NB I have a Mopar timing tape on my damper so I donâ€™t really care if I have to move the engine multiple times. Still only turn it twice overall.

Cheers

Henry

From: chrysler-300-club-international@xxxxxxxxxxxxxxxx [mailto:chrysler-300-club-international@xxxxxxxxxxxxxxxx] On Behalf Of rob bohuslav
Sent: Saturday, 13 February 2021 5:58 AM
To: John Grady
Cc: Chrysler 300 Club International
Subject: Re: {Chrysler 300} valve lash adjustment hemi

Not sure if this helps..... but this was an old decal that was used and stuck under the hood of many a Mopar back in the day:

<image001.jpg>

On Fri, Feb 12, 2021 at 2:48 PM John Grady <jkg@xxxxxxxxxxxxxxxxx> wrote:

Without overly complicating it,I was starting to do this and laid out firing order 392 vs crank degrees. 413 the same firing order , but distributor turns CCW other is CW . My new damper marked every 90 degrees.

392 and A block;( B may be in the same situation, but not there today). Starting with #1, at TDC firing (which position by the way is 360 of crank rotation AWAY (forward CW) from where you align timing chain dot marks..(=confusing as hell , I have ever seen that fact talked about) . Yes , The piston is on TDC when chain marks are aligned ( at install ) , cam key points at about 4 o clock but that is not the compression or firing stroke. On firing stroke on #1 , the dot on cam sprocket is at top (180 more on cam--SO, on next full rotation of engine ---and firing , yes pointer is back at TDC----.and cam has turned one half turn. #1 Piston went down and came back up. Fire!

So, I started overthinking again. ---- on a V8 , 4 firing TDC's happen per turn of crank, 360/4 = every 90 degrees. So, measured degrees from the #1 firing TDC . 1,8,4,3. =0, 90, 180, 270 ; 360 position (start of next turn) is the start of 6,5,7,2 firing ,and yes #1 is at TDC again at 360 but not firing ; 360,450,540,630. So 720 is 0 again ,same as # 1 firing . 720 Crank degrees. that is = 360 distributor and cam degrees , rotor is back pointing at 1. = 18436572

Now all through Mopar land is some kind of chart ( I have a copy) saying adjust I 2 and E 8 when # 1 is at TDC on compression / firing stroke , = still requiring 8 bumps of crank by 90 each , to do 16 valves . I do not get this advice from on high at all. If #1 is firing on TDC by definition both valves are closed, that is when to adjust #1 valves ? Especially if moving it 8 times anyway. There is probably some pattern where one could move only 4 times, and adjust say 4 at once, why this line of inquiry started in the first place (from me). But instead sometimes 40 posts in an online sequence with guys killing each other over how to do this, but none of them advocate what I just said. They confuse themselves with the base circle and " heel" (??) of cam etc . Tangled in underwear? Base circle is a long time % duration of cam, certainly where both lifters are sitting when cylinder fires?

Wha???? is my reaction. Anyone with me? Thoughts?? "for those who do not understand, no explanation suffices" is my reaction to all this, but maybe I am missing something important!???? If so, not alone..

Best, John G

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