Rocker Decision

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nm9stheham said:
Part of the trick to getting close is to try to account for the effective closing point of the intake valve (discussed in the middle of the page that you linked). For example, I'll subtract 8-10 degrees from advertised duration for a solid cam to account for lash, and put that into the Pat Kelley calculator.
It is not a perfect science. But you have to do something to get in the ballpark with DCR if you want to know what you are going to have.
Click to expand...

That much, Eh?
I had heard those numbers before, but I've never run a solid. ........Although I once put some USED 273 solids and adjusters on a factory 340 automatic cam,lol. I think that was about 1975.
I've been using 6* on the Voodoos for purposes of comparison. I was thinking it wasn't enough but have only bumbled around in the dark with those occasionally, and not to the point of it's being critical.
But then; I use the .006 FTH numbers mostly as gospel too,and assuming the lifter is fully self-adjusted to zero lash, knowing full well the valves may not be fully closed yet. That's all I got to work with. I do the best I can. My main concern is always that JoeMopar (not his real name,lol) doesn't stick a 292/108 in his 8/1 teener,lol, and to explain,using examples, why that is a bad idea; including that it's a PITA and expensive mistake to make.
Thanks for disclosure.
If there is a next cam for my combo, it will be a solid. I have been itching for a decade to run one, but my 230FTH won't die, daymnit.
 
good on ya mate
expansion ratio is underappreciated, also compression related
a lot depends on the lash on the solid

nm
take a crack at this cam on left Direct Connection 260 on right
265 @.004 284
256° @.006 269
246 @.008 260
202° @.050 212 ---newer grind may be 221/228 some were 221/221 over the years
120 @ 200 115
64 @ 275 DC 260 is 42
 
AJ/FormS said:
That much, Eh?
Click to expand...
It is just my best guess at this point. I don't have any 'solid' (pardon the pun) data to say how much to subtract from the solid cam's advertised duration, but I know I need to do something. As an aside, it has occurred to me that part of the reports of solids running better for a lot of guys is better low RPM torque due to higher DCR from a shorter' effective' intake duration. (But we'll never know for sure...)

AJ/FormS said:
My main concern is always that JoeMopar (not his real name,lol) doesn't stick a 292/108 in his 8/1 teener,lol, and to explain,using examples, why that is a bad idea; including that it's a PITA and expensive mistake to make.
Thanks for disclosure.
If there is a next cam for my combo, it will be a solid. I have been itching for a decade to run one, but my 230FTH won't die, daymnit.
Click to expand...
Yep, I agree, you work these numbers out, as it is what you can do on paper to avoid the big mistakes, either too high or too low. I think I have mentioned my 300 duration cammed Opel 1.9L with 7.6 SCR... works out to the upper 5's for DCR LOL. DEADSVILLE below 3700-3800 RPM... only worked for rallying (to some degree) since you could rev that motor to 8k all day long. You can't recover like that on a stock 318 bottom and heads.

Wyrmrider said:
nm
take a crack at this cam on left Direct Connection 260 on right
265 @.004 284
256° @.006 269
246 @.008 260
202° @.050 212 ---newer grind may be 221/228 some were 221/221 over the years
120 @ 200 115
64 @ 275 DC 260 is 42
Click to expand...
Help me a bit here.... the left side numbers are for one cam, like a .904 cam, and the right side numbers are for the DC 260 cam?

What I get from both sets of numbers is that one may have to subtract MORE than 10 degrees from advertised duration for a typical .015"-.018" lashed solid cam. Is that where this is heading?
 
correct the left numbers are from an old cam doc profile of my dodge motorhome cam and the right are DC 260 for comparison (it's really more like the 268 comp but better) ie bigger on the seat but less around the nose where it counts
I had the DC 260 before I changed true 9:1 motor, ported 915 heads .030 quench , D Dished 6 pack pistons, etc
shouldwork good in any low compression motor I have another .904 cam about 192 .050 duration which we used in propane heavy transit busses
either cam plus quench reduces EGT around 800 degrees in a Propane Bus hence the pop up pistons
 
Wyrmrider said:
I can't tell what cam it is from thepic
but I'd usually run the higher lift shorter duration version of whatever it is
if you looked at the A new article with photos on the T/A & AAR rocker arms with a W2 / W5 rocker arm comparison
you can see where the oils want to be for the pads and balls- look at the w2s The TA's are like yours
drilling and plugging is not hard - and I'd still oil through the pushrods
there is a reason MA MOPAR made these changes
do you have the cam/ lifters already?
I can't even tell if it's solid or hyd
would new glasses help?
Click to expand...
Comp Cams 20-225-4
Hydraulic
I have the cam
Don't have lifters or rods yet
 
so check into AMC/MAgnum lifters and hollow ball/ cup pushrods
pushrod seat height may be different
how did you end up with the older chevy version instead of the HL version? will they swap?
unless you have max compression and you are trying to bleed off some dynamic compression the 274 HL might work better
cheers
do the mid lift geometry determination before ordering pushrods- adjuster almost all the way up to the max - forget the old 3 threads rule because the new adjusters are longer- you may have no threads showing with these
 
Wyrmrider said:
so check into AMC/MAgnum lifters and hollow ball/ cup pushrods
pushrod seat height may be different
how did you end up with the older chevy version instead of the HL version? will they swap?
unless you have max compression and you are trying to bleed off some dynamic compression the 274 HL might work better
cheers
do the mid lift geometry determination before ordering pushrods- adjuster almost all the way up to the max - forget the old 3 threads rule because the new adjusters are longer- you may have no threads showing with these
Click to expand...
Thanks for all the help. much appreciated.
Not sure what you mean about the Chevy version.
Comp Cams website does say that this cam is for Chrysler 273-360.
 
The Billet/ cam core is for a Chrysler
The master was designed for a Chevy
just compare XE285H with the XE285HL where the Master is designed for a Chrysler
why use a chevy master- cheaper for them and chevys are all the comp tech staff really knows
Mopar 440 Update - Car Craft Magazine
has comparison dyno runs on the 274 versions
ask more questions
 
Wyrmrider said:
The Billet/ cam core is for a Chrysler
The master was designed for a Chevy
just compare XE285H with the XE285HL where the Master is designed for a Chrysler
why use a chevy master- cheaper for them and chevys are all the comp tech staff really knows
Mopar 440 Update - Car Craft Magazine
has comparison dyno runs on the 274 versions
ask more questions
Click to expand...
The machine shop I went to for my valve job and head work told me they wouldn't recommend any more lift than this cam offers unless I upgraded the valvetrain.
 
you might be better off with the HE 274HL depending on all the variables of compression, gears, weight and how you want to drive it
you will get more torque
what do you mean upgrade the valvetrain
just run iron rockers what else could you upgrade
 
A street car

yr asked
What are you using for valve gear?


your HE284H cam is here street-strip wants 3000 stall and gears

20-225-4 - Xtreme Energy™ Hydraulic Flat Tappet Camshafts

shows intake close at 68ABDC

.507 lift



XE285HL is here

20-228-4 - Xtreme Hi-lift Hydraulic Flat Tappet Camshafts

shows intake close about the same 69ABDC but 545 lift also 3000 stall

I've run those iron rockers with 550 lift

will work fine with a dual plane also and better for street and a real 9.5 cr



XE274HL is here

20-227-4 - Xtreme Hi-lift Hydraulic Flat Tappet Camshafts

.525 lift so should even be okier

but it closes the intake at 64ABDC instead of your cam at 68ABCD



you want a street build

4 degrees makes a big difference and the extra lift should give you the same top end and more bottom end and mid range

only takes 9:1 or better and does not require 3000 stall



why leave performance on the table

heck comp still sells the even older 280H take a pass on it and the



IMHO THE TOP TWO CAMS ARE MORE STREET-STRIP THAN STREET

not knowing your build details from this thread are they posted elsewhere?
 
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