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Rocker arm ratio
https://slantsix.org/forum/viewtopic.php?t=60476		 Page 1 of 1
Author:  MOUSETRAP [ Mon Nov 21, 2016 3:43 pm ]
Post subject:  Rocker arm ratio
So all my reading says stock rockerarms for solid lifter engine have a real ratio of 1:45 to 1:55
Roller rocker set up is not $$ for me
I am building this with HP and performance being very important

So I am looking to get a few sets and try to matched set
Question is
#1 is it worth it my OCD SAYS YES and I have the time

#2 I'll measure cam lift .. then valve lift should give me the ratio ??

#3 is there a bushing in the rockerarm ?

#4 how much play on rockerarm on the shaft is normal ?

Thanks
Author:  '67 Dart 270 [ Mon Nov 21, 2016 4:50 pm ]
Post subject:  roller rockers
Don't want to usurp your thread, but can any responders also opine on whether roller rockers are quieter than stock ones (assuming proper adjustment of both).

b
Author:  DusterIdiot [ Mon Nov 21, 2016 5:32 pm ]
Post subject:  Lol...
Quote:
#1 is it worth it my OCD SAYS YES and I have the time
You can do that, although you may find that most of the matching rockers may only fall in the 1.45-1.47 range and it's only good for uniformity and not much on gaining an extra .001 of lift.... that being said my last couple of drag heads with matched ratio stock rockers took me going through 12 rocker sets to get 1 good matched set and another somewhat matched set...
Of course I had the time and I had the parts, and some beer and a few albums worth of tunes to keep things from wandering.
Quote:
#4 how much play on rockerarm on the shaft is normal ?
Normally they are a bit loose and can have a fair amount of side play... you can mix and match a set of rings and bolt washers to get a set that doesn't 'wiggle' as much side to side....
Author:  MOUSETRAP [ Mon Nov 21, 2016 6:16 pm ]
Post subject: 
Ouch !!!! 12 sets I'll measure what I have and make a decision
Author:  slantzilla [ Mon Nov 21, 2016 6:56 pm ]
Post subject:  Re: roller rockers
Quote:
Don't want to usurp your thread, but can any responders also opine on whether roller rockers are quieter than stock ones (assuming proper adjustment of both).

b
Rollers are usually somewhat noisier.
Author:  Killer6 [ Sat Nov 26, 2016 12:06 pm ]
Post subject:  Re: Rocker arm ratio
Quote:
So all my reading says stock rockerarms for solid lifter engine have a real ratio of 1:45 to 1:55
Roller rocker set up is not $$ for me
I am building this with HP and performance being very important

So I am looking to get a few sets and try to matched set
Question is
#1 is it worth it my OCD SAYS YES and I have the time

#2 I'll measure cam lift .. then valve lift should give me the ratio ??

#3 is there a bushing in the rockerarm ?

#4 how much play on rockerarm on the shaft is normal ?

Thanks

The ratio of pad style OE rockers actually changes thru the lift cycle.
As it "rocks" it moves the point of contact w/the valve stem back & forth.
The valve stem height will change where this point starts. higher than
stk. moves it in, reducing the ratio. The rockers are 1 piece w/the sleeve
portion induction welded in place, then hardened. Mopar sold shim thk.
washers to align & space/tighten rockers, BB shafts are the same dia.
Making sure the rocker angle/valve tip alignment is correct will net you
the best results, but selecting the best(if there are any) can't hurt!
Author:  '67 Dart 270 [ Sat Nov 26, 2016 5:59 pm ]
Post subject:  noisy roller rockers
Thanks Slantzilla,

So, the main advantage of roller rockers is less friction at high rpms? I don't know, I'm assuming roller engagement with valve stem is better for friction, i.e. heat reasons, more efficiency means more HP for a race engine with roller rockers? If they are louder, it seems like it only makes sense for a high rpm engine, where one is revving the crap out of it all the time.

Third question: why are are PP&R's roller rockers $1350?! https://www.pentastarparts.com.au/store ... tail&p=811

With CNC and modern manufacturing etc. be ubiquitous.; it seems like anything like this should be maybe $500. I suppose it is supply and demand, very limited supply and a marginally bigger volume of demand.

Brian
Author:  Killer6 [ Sun Nov 27, 2016 8:40 pm ]
Post subject: 
Accuracy in ratio and friction reduction both. Some w/big sticks already have
stated they didn't notice any change in HP, but modest cams might get more
of a bump. I have yet to call, but purportedly T&D's are 'bout $800, and you
can't do much better than that. Those PP&R's come completely loaded tho',
and sure are nice lookin' units!
Author:  DusterIdiot [ Sun Nov 27, 2016 8:57 pm ]
Post subject:  But...
Quote:
T&D's are 'bout $800
At one point in time, the T&D units came without oil passages... so even at that price you still have to modify them, or plumb in a spray bar....

FYI.
Author:  Killer6 [ Sun Nov 27, 2016 9:05 pm ]
Post subject: 
To the OP, the stock rocker w/stk. valves My 1st time 'round on the eng.,
had a pattern that transitioned from 1.4126:1 to 1.5895:1, add & / by 2 &
you have a nearly perfect 1.501:1 ratio avg. The 2nd go w/non-stk. valves
installed by someone else(B4 I bought the equip. to do My own), had a
pattern that transitioned from 1.35368:1 to 1.5895:1 for a 1.4716:1 avg.
ratio. Notice w/a larger cam and the valve tip higher, the contact ended in
the same spot, but the lift curve suffered, costing abut .020" on that cam.
Author:  Killer6 [ Sun Nov 27, 2016 9:07 pm ]
Post subject:  Re: But...
Quote:
Quote:
T&D's are 'bout $800
At one point in time, the T&D units came without oil passages... so even at that price you still have to modify them, or plumb in a spray bar....

FYI.
:shock: , good to know, PP&R's anybody?
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