thoughts on going to 1.6 rockers.

[mentor70]

I had a thought about going to a 1.6 rocker setup on my 440.

currently is a 440 with CNC ported Stealth heads, ive got the Icon forged pistons with plenty of relief.

cam is a Lunati hydraulic roller 560 lift.

it may no be worth it because of the stability issues over 6k rpms and may not yield any gains, but i thought id throw it out here and see what responses i get.

 

[rumblefish360]

I’d go for it with new springs (slightly stiffer/more pressure) to handle the higher lift.

 

[66Satellite47]

What stability issues are you concerned about? The CNC ported heads MAY like more lift. All depends on what your performance goals are. The springs may or may not work, depending on what spring they are. 1.6 rockers have been commonly used on BB Mopars for years now. Of course you'll need to check the pushrod clearance.

 

[69 GTX]

I used 1.6s on my 440+6. I wanted a pretty tame duration 238/242 so I tried to make up for it with a little more lift. My shift point will be 5800-6000 so I wasn't concerned with stability. Took my cam from.590 to .630 I also used a solid roller so I wouldn't have to worry abought lifter instability either.
440 .030 9.9 pistons 240 trick flows & 6bbl 590 hp by Jim LaRoy

 

[lewtot184]

the benefits of changing rocker ratio may depend on the rocker ratio you have now. all the aftermarket adjustable rockers I've tested will yield a ratio higher than they are rated. for instance; if you have an adjustable 1.5 it may actually check 1.6. if this is true then going to a "rated" 1.6 may only be 1.65; not much there to gain. if you have a true 1.5 and step up to a 1.6 there really isn't that much power increase for the money spent; maybe 5-7hp. of course there are the retainer to seal issues to look at with a lift increase. best thing to do is weigh the benefits to the cost and do your homework.

 

[rumblefish360]

I don’t know where he thinks rocker stability is compromised or weak. A quality set up will include a good shaft with the rockers. A good set of hold downs should be done ncluded to top it off.

BAMM! Done!

 

[not so famous bob]

the benefits of changing rocker ratio may depend on the rocker ratio you have now. all the aftermarket adjustable rockers I've tested will yield a ratio higher than they are rated. for instance; if you have an adjustable 1.5 it may actually check 1.6. if this is true then going to a "rated" 1.6 may only be 1.65; not much there to gain. if you have a true 1.5 and step up to a 1.6 there really isn't that much power increase for the money spent; maybe 5-7hp. of course there are the retainer to seal issues to look at with a lift increase. best thing to do is weigh the benefits to the cost and do your homework.

Also spring coil bind, and seal clearance needs to be checked. I would think ported heads could use .040 more lift ! Probly more duration too.

 

[451Mopar]

My 505 stroker has stealth heads, and the Comp XR286HR hydraulic roller cam with the Harlan Sharp 1.6:1 rockers. Originally I tried using some cheap 1.7:1 rocker arms, and the engine ran good, but the roller tips of the rocker arms were showing wear with just a few hundred miles on them so I put the HS rockers on to avoid valve train hassles.
Not sure how much difference the ratio will make, but it makes valve spring selection more difficult.

 

[wyrmrider]

I've run the 1.75 non roller rockers- some grinding to make them fit- more with 3/8 pushrods
I'd wait till you have the motor available to put it on the stand if necessary or at least be able to pull the intake manifold, cover the valley and remove all the chips
just do the intakes

 

[BSB67]

The hydraulic lifter is the weak link. Increased rocker ratio and increased spring pressure together add considerable force at the lifter that it might not be able to handle. Will it hurt performance? help, or be a wash? Could be any of these. And you wont know one way or the other unless you do back to back testing at the track or on a dyno.

 

[threewood]

On the Stealth heads, you will need to clearance the pushrod channels. I am using thick walled 5/16" pushrods with a 1.5:1, nothing special and they needed to be clearanced.

 

[1967coronet440]

I seen an episode of engine masters where they took an engine and only changed from 1.5 to 1.6 and picked I want to say almost 30hp. Search it on YouTube. I have no idea but I’d guess that number will vary from engine to engine.

 

[rumblefish360]

Yes! Every engine, every cam, every combo, results change. They will always be positive IF the heads can handle the lift, have good flow capability at the higher lift and the engine combo wants more lift.

Hyd. lifters can handle the extra ratio. The spring pressure, if increased to much will overcome the lifter from correctly operating. This can be seen on a dyno with the upper hp falling off. This can also be due to a weak spring. Before and after runs are needed to know which is which.