The Purpose Of 1.6 Rockers

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Aside from the slight increase in lift and duration at .050, compared to stock stamped rockers most aftermarket 1.6 rockers would give you:

1. more precise and consistent ratio (machined vs. stamped)
2. a rollerized tip to reduce friction and side loading on the valve tip
3. lighter weight for higher rev capability (debatable depending on design)
4. adjustability

Plus they look cool. :headbang:
 
Does anyone know what the current theory is on how much duration you pick up going to a 1.6 rocker? I have an OLD Crane master catalogue and it states that going from a 1.5 rocker to a 1.6 it is the same as going to a 3 to 4 degree bigger cam. Anyone got any thoughts?
 
Mike, the other bonus is it moves the valve a further distance (lift and duration), in the the same amount of time. So the valves are actually moved faster.
 
raymond said:
Does anyone know what the current theory is on how much duration you pick up going to a 1.6 rocker? I have an OLD Crane master catalogue and it states that going from a 1.5 rocker to a 1.6 it is the same as going to a 3 to 4 degree bigger cam. Anyone got any thoughts?
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Well to be truthfull, the duration (both advertised and at 0.050") is totally independant of the rocker arm ratio. These are camshaft specifications and the measurements ares taken at the lifter, not at the valve. So it stays constant regardless of wheather you have 1.5, 1.6 or even 1.8 to one ratio rocker arms. But what DOES change is the amount of valve lift at that 0.050" point.

Here is an example. At 0.050" of cam lobe lift with a 1.5:1 rocker, the lift at the valve is 0.075". Now with a 1.6:1 ratio rocker, it would be 0.080" lift at the valve. That is a difference of only 0.005". But if you were to rotate the camshaft a little, you can find where the valve is open 0.075" again. The amount you had to rotate the cam in degrees is the effective duration that the 1.6 rockers add. This amount will not be constant from one camshaft design to the next. It is totally dependant on the ramp of the cam lobe.

So to say 1.6 rockers always add 4 degrees of effective duration would be total BS. You would literally have to measure a specific camshaft to determine this value. Not only that, but it is very likely the intake lobe and exhaust lobe would have different profiles. So you would need to measure both.
 
mikesduster said:
beside more lift and duration WHY switch??.....
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Aside from all the reasons posted 1.6 rockers will help grind your cam into dust quicker if you have incorrect valve train geometry. :laughing:

teardown12.jpg


Which reminds me.... I should have my motor back next weekend. Maybe THIS time I'll get it right! 8)
 
IT all about lift and adjustability. 1.5 versus 1.6 is about .030 differance. That's how much more the valve will open in the head. Adjustability helps even out every thing from chamber to chamber. Say you are running a 508 lift cam with 292 duration. With 1.6 rockers you now have a 538 lift cam with 292 duration. Remember geometry changes a little too.
Good luck,
Mike
 
i HAD a MP.508 but like moper said" I DONT NEED THEM TO GRIND A CAM TO DUST!!!...AND LIFTER TOO!!!".....im running STOCK/OLD rockers on my NEW comp XE294H CAM which is .519/.524....im sure the lift is no where near that with my old/stock rockers and ive run a 12.07@108 in street trim already!!!!!,THANKS to MOPER!!!! :headbang:

now,im hopeing to run BETTER/FASTER with the NEW pro-magnum lifters and 1.6 rockers....i think moper is right,its about the valves opening/closing.
 
One small thing is the mass of lifter(s) and pushrod(s), more camlobe moves that mass more it robs hp(inertia), and the valvespring has to push that mass back. With 1.6 or 1.7 rockers you can use "smaller cam". For me its allthe same, but there is people that hunts for that last horse(kW).
13.5@111 el cheapo 4D -73 Dart 1580kg
 
The difference betweeen a 1.6 Vs 1.5 is 7% so if you have a 520 lift cam the 1.6 rocker will bump the lift by 7% or to .556.

All 1.6 rockers is a Chevy deal, a Mopar WILL make more power with a 1.6/1.5 rocker combo. By putting a bigger lift on the intak side you get the Air-In higher wih the bigger lift. The key to scavenging the combustion chamber is velocity and by leaving the 1.5 on the exhaust you will increase that vlocity and scavenge the Combustion chamber cleaner=More power.

Bigger is not always better, you have to do the calculations and understand the physics of an internal combustion engine and how valve overlaps relate to scavenge based on lift, duration, port sizes, header tube legnth and size, valve size, rocker arm rations etc. Changing the rocker arm ratio is NOT the same as splitting the lift on the cam lobe.

Changing the rocker arm ratio does almost nothing to the duration. If you really want the inside scoop on how a split ratio rocker arm system works give Jim at Racer Brown a call and he'll explain it in detail.

Racer Brown Cam Engineering....410 866-7660 after 2 PM EST

Here's Jimmy's set up
http://www.4secondsflat.com/Racer_Brown_Rocker_Arms.html
 
I have roller lifters with my 1.6 roller rockers, haven't ground anything to dust yet except the band in my tranny. I changed it and was rewarded with a nice leak at the converter. Honestly though, I've only ever killed one cam with 1.6 rockers and it lived for 17 years in three different engines. Buy a good cam and put whatever rockers you think you want on it. Experiment a little. There alot of them out there so I'd say there's probably something to it. There's alot to be said for split duration cams and splitting rocker ratios, unfortunately I'm not smart enough to say anything about it. I do know that longer rocker ratios can produce significant gains, but the cam they are being used on definitely matters. Try them both and decide for yourself, then let us know. The almighty dragstrip will not lie to you...
 
FWIW, the magnum engines come from the factory with 1.6 ratio rockers.
 
Quote: "The almighty dragstrip will not lie to you..."

The cheapest and best Dyno you'll ever find
 
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