Re: Cam Questions

[Don Dulmage <big-d@xxxxxxxxxxxx>]

lobe lift (off the pushrod since that is working for you) X 1.5 -.006= net 
valve lift for hydraulic cams. Because a hydraulic lifter  bleeds down it is 
almost impossible to get a lift figure using it.. If you had adjustable 
rockers you could pop in a solid lifter and set it at zero lash. The - .006 
and the amount the hydraulic lifter sucks up in the process  of absorbing 
the wack. BUTTTTTTTTT if that was a solid cam there would not be .006 but 
.024 to .032" valve lash.
Since we are on the subject anyway let me say Cam specs area given even for 
solids at .000" lash for most manufacuturers. No one thinks of this so they 
run a .510 list solid lifter cam thinking that will be better than a .510 
lift hydraulic forgetting in the process that the solid cam specs are at 
.000" lash and in reality that cam will have only .486 lift with its .024 
valve lash whu ile its hydraulic twin will give the whole .510" minus 
about.006 for 504" lift in actual running conditions. On top of that the 
solid cam has long ramps to ease the lifter up snug and let it down so it 
doesnt bounce . These take up about 7 degrees either end of the lobe so it 
wastes about 14 degrees total duration just getting ready to work. The 
hydraulic doesnt need this since it is right there snug on the end of the 
pushrod all the time so less duration is required for the same RPM. range. 
That is why we often compare durations at .050" and .100" and even .200" 
just to make sure what we are actually gettting. So whay do we use solids? 
Because first years ago before the late sixties it was not possible to turn 
higher Rpms with hydraulics so solids were an automatic choice. Even now my 
Max wedge never sees above 6500 . It doesnt need to so i run a hydraulic cam 
of similar lift and duration as the old Max Wedge solid cam but I get more 
performance for the above reasons. Since i never need to go to 7000+ it is 
for me a no brainer.
Now i know your buddies with their little duntov corvettes and such will get 
ticked off if you try and explain this to them and those who are in love 
with solids will also. That is the wonderful thing about the truth. It 
doesnt matter who believes it. It is not a demoratic function based on 
votes. It is just the truth , period.   Sometimes in a racecar you cant find 
a cam you like in hydraulic grinds and so you search solids keeping in mind 
the principles mentioned above. If you do your math right and allow extra 
duration and extra lift because of the ramp thing and the valve lash, it 
works. If not it doesnt.
----- Original Message ----- 
From: "Dennis C." <dennis.2914@xxxxxxxxx>
To: <1962to1965mopars@xxxxxxxxxx>
Sent: Monday, January 26, 2009 12:45 AM
Subject: Cam Questions


> Hello,
>
> Does anyone know what the stock rocker ratio is for a 383?
>
> Do the stock rockers have the same ratio for intake and exhaust?
>
> And last, is it possible to get a rough idea what the lift is of an
> installed cam with hydraulic lifters by reading the lift at the pushrod
> end of the rocker with a dial indicator?  I can not reach the valve end
> of the rockers with my dial indicator stand.
>
> Any help will be appreciated.
>
> Dennis C.
>
> 1996 Dodge Ram 3500 Van Conversion
> 1964 Plymouth Belvedere 318 Auto
> 1963 Plymouth Sport Fury 383 4-speed
> 1949 Dodge Pickup 289/C4 soon to be changed
> 1998 Honda Valkyrie Standard
>
>
> ----
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----
Please address private mail -- mail of interest to only one person -- directly to that person.  I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic.  Thanks!

'62 to '65 Mopar Clubhouse Discussion Guidelines:
http://www.1962to1965mopar.ornocar.org/mletiq.html.