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Increasing rocker arm ratio
https://slantsix.org/forum/viewtopic.php?t=21526		 Page 1 of 1
Author:  BigBlockBanjo [ Fri Jan 19, 2007 10:23 pm ]
Post subject:  Increasing rocker arm ratio
Hey guys,
I was reading around in my "Polyspherical High Performance" book, and there's a section in there about modifying rockers. If you have a "Victory Library" manuel......it may be in there.
Anyway, he talked about welding/brazing the outboard side of the adjuster hole closed, then drilling a new hole .100 closer to the shaft. If done to an arm with 1.5 ratio, you end up with a 1.67 ratio.
Sounded great to me, although I would be worried about the heat; and trying to fing a die set to match the adjuster. Example: If my cam has .480 lift at the valve now, it would have .534 after the change. Imagine the valve lift velocity rates......... :twisted: Only downside would be all the time it would take, as you would have to take it slow.

While I'm on the subject.....For all those who are still possibly looking at a Clifford camshaft. They advertise the lift of their cams using a 1.6 ratio rocker arm. The "special" 268 cam, with .477 lift, really has .447 with stock rockers. So....they really can not produce the torque that other, newer designs do. Personally,....it's almost like those old "Blue Racer" cams. Crazy duration and stock lift. Good for some things I guess....... :)
Take care,
BBBanjo
Author:  emsvitil [ Fri Jan 19, 2007 10:39 pm ]
Post subject: 
How much for high-ratio rockers vs how much time to modify rockers......................
Author:  BigBlockBanjo [ Sat Jan 20, 2007 9:14 pm ]
Post subject: 
I know they make 1.6 rockers, but do they make 1.67??? To me that's a considerable increase. I thought about it, and if you had all the tools, and everything together; it would take about 1 hour per rocker. 12 hours of work...that isn't bad......If you have a free weekend with nothing else to do. :D The slant won't get it, but I will probably try it on my Poly 318. Check out the price for a set of those HR rocker arms... :shock:
Take care,
BBBanjo
Author:  emsvitil [ Sat Jan 20, 2007 9:19 pm ]
Post subject: 
Having all the tools is the key (and an extra set of rockers....)

1 hour per rocker................ don't think so....

1st rocker 4 hours
2nd rocker 2 hours + 1 hour to figure out how to assembly-line the remaining 10.....

remaining rockers 5 hours.


The 12 hours sounds about right. :roll:
Author:  emsvitil [ Sat Jan 20, 2007 9:30 pm ]
Post subject: 
I'm wondering if you can kinda squish the rocker arm to improve the ratio.......


Some ascii art: (ignore .. they're used to line the pic up)

..O screw adjustment
..|| normal
=== shaft
..||
..||
..# valve

to

..O screw adjustment
..() bend and spread here so screw adjustment is closer to shaft
=== shaft
..||
..||
..# valve
Author:  BigBlockBanjo [ Sat Jan 20, 2007 10:01 pm ]
Post subject: 
Great Idea! I never thought about "squishing" the short side. Same road, different lane....
The trick would be keeping the threads together at the inside seam, as they would try to seperate when you started "squishing" :? If you had a spare rocker shaft, you could make a die to slide the rocker onto, to retain the shape of the cylinder. It's one of those things that will end up being easy, but you'll go around the world to find out how. :)
Author:  emsvitil [ Sat Jan 20, 2007 10:48 pm ]
Post subject: 
11 hours 54 minutes to make the squish tool


6 minutes to squish 12 rockers............
Author:  Sam Powell [ Sun Jan 21, 2007 5:21 am ]
Post subject: 
I made a tool from an old shaft and dial gauges to check the actual ratio. Turns out a stock set varies from 1.45 to 1.6. I picked out the high ratio ones from two sets and used those. A few of them were actually 1.5, but most fell either below or above. It took three full sets of stock rockers to make a set of high ratio rockers. There's more to the story than that, but that's the simple version, and you could do the same if you wanted to try. I don;t know if they all vary that much, but mine did. I marked them on the side, and stored them away until it was time to use them. I don;t know how long it took. I have never kept track of that kind of thing.
Sam
Author:  argentina-slantsixer [ Sun Jan 21, 2007 7:36 am ]
Post subject: 
here's my ascII art suggestion

=====o===
X T

(valve - shaft - pushrod side, normal view) then you slice it and TIG or MIG weld it like this


=====O==
X T
Author:  slantzilla [ Sun Jan 21, 2007 8:30 am ]
Post subject: 
I have a set of the 1.6 rockers. I have tested them back-to-back against a set of stock rockers. I won't really elaborate on what I found, but I have run faster with stock rockers than I have the 1.6's. :shock:
Author:  argentina-slantsixer [ Sun Jan 21, 2007 1:10 pm ]
Post subject: 
Quote:
I have a set of the 1.6 rockers. I have tested them back-to-back against a set of stock rockers. I won't really elaborate on what I found, but I have run faster with stock rockers than I have the 1.6's. :shock:
1/4 times? I wouldn't kn ow how to translate that track experiment to an everyday driver... say if you was spraying or not, or what cam do you use and how much carburetion and with what amount and type of headwork... for a stocker or a mildly modified stoker, I think 1.6 rockers might be better (maybe not and I'm just thinking that your ride would have too many differences with a street driven car for standing a chance of actually compare your findings, wich are not being discussed... I made myself clear? mmmm... don't drink and type HEHEHHE)
Author:  panic [ Sun Jan 21, 2007 1:42 pm ]
Post subject: 
There a reason why many high-ratio trials produce disappointing results: the engine was already scienced-out in terms of duration, intake closing and overlap, and the big increase in the overlap triangle pushed the effective cross-flow point up above the existing torque RPM. Have you tried only 1.6 intakes to kill some of the overlap?
High-ratiuo is most effective with cams known to be too mild (or stock), less with hot cams, and frequently mixed results as the cam choice got closer to what the engine wanted.
Remember that moving the rocker stands laterally is not fun especially with the oil supply. The "long" (valve) end is limited to where the tip runs off the stem, but a lash cap gives more area and raises the valve putting the stem farther away. The "short" (pushrod) end is limited by the pushrod clearance in the head.
Author:  slantzilla [ Sun Jan 21, 2007 4:00 pm ]
Post subject: 
Quote:
There a reason why many high-ratio trials produce disappointing results: the engine was already scienced-out in terms of duration, intake closing and overlap, and the big increase in the overlap triangle pushed the effective cross-flow point up above the existing torque RPM. Have you tried only 1.6 intakes to kill some of the overlap?
High-ratiuo is most effective with cams known to be too mild (or stock), less with hot cams, and frequently mixed results as the cam choice got closer to what the engine wanted.
Yep. Big rockers work well with a stock cam and head. Anything with a cam that works with the head flow abilities won't see squat with them. :D
Author:  Ron Parker [ Sun Jan 21, 2007 5:03 pm ]
Post subject: 
I put a set of 1.6 roller rocker arms on my base stock engine several years ago over the stock 1.5. The car picked up about 2 hundereds of a second in the 1/8. I figured that was the 1.6 rockers give a little more lift and maybe a little less friction. Thanks Ron Parker :D









Were Going To Blow Bagel Away This Year
Author:  dakight [ Sun Jan 21, 2007 6:07 pm ]
Post subject: 
Quote:
I put a set of 1.6 roller rocker arms on my base stock engine several years ago over the stock 1.5. The car picked up about 2 hundereds of a second in the 1/8. I figured that was the 1.6 rockers give a little more lift and maybe a little less friction. Thanks Ron Parker :D

Dunno about that, but it does increase pressure on the lifters and cam, maybe not a lot but definitely some.








Were Going To Blow Bagel Away This Year
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