Re: Stamped steel BB rocker arm ratio?
[Re: Junky]
#107548
08/20/08 02:49 PM
08/20/08 02:49 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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Posts: 16,123
Grand Haven, MI
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shouldn't alter the powerband, just raise it, IF your heads could benefit from increased lift. most OEM mopar heads peak flow in the .450-.5" lift range without porting, so odds are you'll see minimal butt dyno gain just from the rocker switch...
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Re: Stamped steel BB rocker arm ratio?
[Re: patrick]
#107549
08/20/08 03:04 PM
08/20/08 03:04 PM
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Joined: Jan 2003
Posts: 5,186
Wherever I am.
Junky
OP
master
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OP
master
Joined: Jan 2003
Posts: 5,186
Wherever I am.
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Quote:
shouldn't alter the powerband, just raise it, IF your heads could benefit from increased lift. most OEM mopar heads peak flow in the .450-.5" lift range without porting, so odds are you'll see minimal butt dyno gain just from the rocker switch...
You're saying my 346 heads that have been blended and have a 3 angle valve job wouldn't benefit with increased lift above .450?
Right now with the .462 (calculated at 1.5 ratio) cam lift on the intake valve, with stamped steel rockers at 1.4 ratio, the actual lift is .430, not .462. So I need a "real' 1.5 rocker to get the full potential out of my heads. Right?
If my heads can't do anything with a valve lift above .450, I'm wondering what would be the best cam for my 383. 
This cam and rocker ratio stuff can fry a few brain cells.
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Re: Stamped steel BB rocker arm ratio?
[Re: Junky]
#107551
08/20/08 03:41 PM
08/20/08 03:41 PM
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Joined: Jan 2003
Posts: 4,574
Upper Midwest
Black_Sheep
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master
Joined: Jan 2003
Posts: 4,574
Upper Midwest
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Stock stamped rockers are supposed to be 1.5:1 but I recall reading somewhere that they are actually closer to 1.4...
'69 Plymouth GTX
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Re: Stamped steel BB rocker arm ratio?
[Re: maximum entropy]
#107554
08/20/08 05:43 PM
08/20/08 05:43 PM
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Joined: Jan 2003
Posts: 10,686
North Dakota
6PakBee
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I Live Here
Joined: Jan 2003
Posts: 10,686
North Dakota
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Quote:
Quote:
Stock stamped rockers are supposed to be 1.5:1 but I recall reading somewhere that they are actually closer to 1.4...
measure them for yourself. i've measured jillions of 'em, and they've all been almost exactly 1.5. ok, maybe not jillions, but some.
I use the stock rockers as I don't use a lot of spring pressure. The stock six-pack springs are about as crazy as I get. Over the years I've measured a lot of rockers also and they are anything but consistent. I have never worried about ratio, just the lift at the valve for an individual rocker arm all other factors being equal. I use a solid lifter, an adustable pushrod, a relatively weak spring, a dial on the valve retainer, and an actual cam to go through batches of rocker arms. I try to split them up into two groups that have equivalent lifts. The higher lifts go on the exhaust and the lower lifts on the intake. Always worked for me. As a side note, this entire procedure is one Racer Brown had since the mid 70's.
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Re: Stamped steel BB rocker arm ratio?
[Re: lewtot184]
#107557
08/20/08 08:34 PM
08/20/08 08:34 PM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
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Quote:
the stamped steels i've measured using a solid tappet, adjustable push rod, and checking valve spring were 1.5. all 1.5 adjustables i've measured, using the above mentioned method, were 1.6. all 1.6's i've measured were 1.65-1.66. going from a true 1.5 ratio to a true 1.6 will add about 5-7 degrees duration at .200 lobe lift, nearly nothing at .050 lobe lift; on the average flat tappet cam. and thats my story and i'm sticking to it.
You want to see a surprising change in your measurement. Get rid of the solid lifter, Take hyd. lifter and shim the plunger to the pre load that you will be using then measure the liftratio. You will be surprised and the difference due to depth of the push rod in the lifter and angle change. You will find that unless using solid lifter on a solid cam with the rocker adjusted to spec. you will be very inaccurtate on a hydraulic cam using the solid lifter. 
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Re: Stamped steel BB rocker arm ratio?
[Re: dogdays]
#107559
08/21/08 10:24 AM
08/21/08 10:24 AM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
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Quote:
Done that a few times, have you?
Would I have brought it up if I hadn't.
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Re: Stamped steel BB rocker arm ratio?
[Re: 6PakBee]
#107561
08/21/08 11:12 AM
08/21/08 11:12 AM
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Joined: Jan 2003
Posts: 25,200
Upper Midwest
MoparforLife
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,200
Upper Midwest
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Quote:
Quote:
Quote:
the stamped steels i've measured using a solid tappet, adjustable push rod, and checking valve spring were 1.5. all 1.5 adjustables i've measured, using the above mentioned method, were 1.6. all 1.6's i've measured were 1.65-1.66. going from a true 1.5 ratio to a true 1.6 will add about 5-7 degrees duration at .200 lobe lift, nearly nothing at .050 lobe lift; on the average flat tappet cam. and thats my story and i'm sticking to it.
You want to see a surprising change in your measurement. Get rid of the solid lifter, Take hyd. lifter and shim the plunger to the pre load that you will be using then measure the liftratio. You will be surprised and the difference due to depth of the push rod in the lifter and angle change. You will find that unless using solid lifter on a solid cam with the rocker adjusted to spec. you will be very inaccurtate on a hydraulic cam using the solid lifter.
Depends what you want. If you are trying to get an absolute lift number at the valve you are absolutely correct. If you just want to compare a batch of rockers against each other, it doesn't really matter.
And I am/was under the impression that it is max lift that is in question being the comparison of 1.5 - 1.6 rockers was used in the original post. Yes, if getting a uniform set of rockers was the issue it wouldn't be a big deal as to which lifters to use. But the lift change do to angle because of push rod depth in the lifter is significant. 
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