Is there any disadvantage to using higher ratio rockers to
obtain more valve lift VS using a larger cam?

For example, rather than swap out a cam for one with
similar duration but more lift is there any reason not to just use
a "higher" ratio rocker?

 

Are you are looking for just an easier way to gain lift? Many times when going to the 1.6 rockers, you must add clearance for the pushrod by elongating the holes in the heads to keep the push rods from binding. Of course, you want to do this with the head off. So now you must pull the heads and the job probably would have been easier if you just changed the cam.

 

The heads will be swapped anyhow. Which is where I am comming from. If I can pick up the lift without having to deal with
the timing chain and cover I am much happier.

The problem being that the peanut cam need some insane
rocker ratio to get anywhere near .450

 

Once you get into 1.7 SBC ratios the cost for rocker arms doubles and your geometry changes. You'll have to do some careful measuring or your asking for trouble. IMHO, go with the bigger cam.

 

*sigh* I was affraid you'd say that

 

GM learned that going with larger ratio rockers give more benefit over larger cam. you can put 1.6 on w/o concern. other than just making sure you don't coil bind the springs. and the pushrods clear the inner side of the hole (towrads stud). your new lift will be .480 with 1.6 rockers. i see no problem with that.

 

I talked with Scorpion about their 1.7 SBC rockers and they said pushrod lenght would not change. However, I can't really find any hard evidence as 1.7s on a small block don't seem to be popular.

 

That's good to know.
Dare I ask aboutr 1.8? *lol*

 

GM learned that if you increase the ratio, the lift increases without having the duration and overlap increase (not by much anyway). This makes it easier to pass the sniffer.

They also learned that they could still make cheap, whimpy, pathetic cams (even on the LS1) and allow the heads to breath better by adding more lift.

Keep in mind that GM is a PRODUCTION company, not a performance company. They don't have any intension of making a high performance engine if it doesn't sell and pass emissions. And all they have to do is make it last longer than 3yrs or 36,000 miles. That's their only goal.

Believe it, OR NOT!!

 

if you have an LS1 a 2.0:1 is in the works for your engine. unfortunately I've never heard of any ration greater than 1.65:1 for SBCs, link me to this 1.7:1 rocker arm from scorpion. sounds interesting...

 

1.7 aint gonna do it LOL
I have a feeling I am gonna end up swapping the cam



305 5spd / 305 AT
GM Part #10088155*

Intake .350"/ Exhaust .384"

Intake duration @ .050" 179*
Exhaust duration @ .050" 194*
LSA 109.0*

 

http://www.dyno-flo.com/proddetail.a...IRA001&from=20

Cheapest place for them, they sell all the flavors. I can't seem to get to http://www.scorpionperformance.com.

 

The main disadvantage of a higher ratio rocker arm is it puts a lot more load on the pushrod and lifter, it's much easier on the valvetrain to get the lift from the cam and not the rocker, I would stay with 1.5-1.6 ratio and just get the proper cam to get the lift you want.

 

BBC rockers can be used (1.7) but that takes some machine shop work to do. But that way, if there are bigger than 1.7 rockers for a BBC, you could probably use them.

 

any way to machine LS1 rockers to fit an Gen I SBC?