1.5 & 1.6 Rocker ratios - What's the diff??

-
A

AUS_Duster

Active Member
Joined
May 29, 2010
Messages
30
Reaction score
0
Location
Melbourne
What factors need to be considered when deciding on installing 1.5 vs. 1.6 ratio rocker arms?

I'm starting to but parts for an engine build and can't seem to figure this one out?
 
Piston to valve clearance, you can get more lift with the 1.6 over 1.5.
 
1.5 rockers lift the valve 1.5 times the lobe lift of the cam, 1.6 lift the valve 1.6 times lobe lift. Generally, 1.6 rockers are used to improve the lift of a camshaft that has low lift. They can also be used to get the valve lift into a specific head flow range. There's really not a need for them, as long as you choose a camshaft with the right amount of lift for your build to begin with. There are other opinions I am sure, but that's mine.
 
I prefer the 1.5 ratio but that's just me. I used the comp pro mags in my 340.
 
OK, take two on the reply...... It's a shorter version because 20 minutes of explaining this again and I'm breaking my I-phone. Here is the short simple version.

.500/1.5=.333
.333 X's 1.6=.533
An increase of .033. Use different numbers for fun.

A custom cam can be done for you by any major or minor cam company to the duration and lift you need. A 1.5 rocker is easier to deal with and set up.
 
.300 x 1.5 = .450
.300 x 1.6 = .480

In this example, a .030 increase in lift, plus there will be a small increase in duration.
 
1.5 rockers are easier?,,,must have missed the memo....Got 1.6 rockers on 3 engines going up and down the track....was no different the setting up 1.5 rockers....LOL

and a fourth engine on the engine stand with 1.6 rockers...
 
Only thing I can add is, with the 1.6, make sure you have pushrod clearance thru the head passage?
 
So if I haven't chosen the cam yet, then use the 1.5 and the desired lift/duration with the cam, rather than trying to gain with a 1.6 ratio - right???
 
AUS_Duster said:
So if I haven't chosen the cam yet, then use the 1.5 and the desired lift/duration with the cam, rather than trying to gain with a 1.6 ratio - right???
Click to expand...

That would be my approach. Everybody does it differently.
 
A 1.6 rocker vs a 1.5 on a std production SB will gain back the lift lost through rotten lifter/pushrod angles.

A cam that has a theoretical of .500 will really have about .475-.480 at the retainer on a SB mopar.
 
AUS_Duster said:
What factors need to be considered when deciding on installing 1.5 vs. 1.6 ratio rocker arms?

I'm starting to but parts for an engine build and can't seem to figure this one out?
Click to expand...
If you have to ask this question you don't need to worry about Rocker ratio. More area in applications where it's needed.
 
RustyRatRod said:
That would be my approach. Everybody does it differently.
Click to expand...
That's inverse thinking to Nascar,prostock and any form of racing where mucho $$$$ are spent to make real HP, but in the OP's application(given the opening Q) it's not a big issue.
 
70aarcuda said:
1.5 rockers are easier?,,,must have missed the memo....Got 1.6 rockers on 3 engines going up and down the track....was no different the setting up 1.5 rockers....LOL

and a fourth engine on the engine stand with 1.6 rockers...
Click to expand...

What your missing is what head that is on top or what it could be changed to in addition to that this is a new guy asking the question. If you use the KISS method there will be less variables to contend with.

The possible areas that could interfere with the pushrods, rockers needing grinding for clearance with what spring is it he is useing now??? With what rocker brand????

You post lends itself to an awaiting disaster or did I miss the memo that all rockers fit without mods? With all springs? Without worry of coil bind?

OldmanRick said:
Only thing I can add is, with the 1.6, make sure you have pushrod clearance thru the head passage?
Click to expand...

It's probably the only other thing missed here so far.

Something's are a bolt on and walk away, something's are not.
 
And you dont check pushrod clearance with 1.5 rockers...so what is the difference...

1.5 rockers will need grinding with the same spring as the pushrod side of the rocker is shorten...not the valve spring side..

I said..the 1.6 rockers will fit with no different mods then a 1.5 rocker.....and as someone who has used 1.6 rockers regularly..

once again...we have people who do things...and other who talk about doing things...LOL

dam..I got 3/8 pushrods with 1.6 rockers with no mods on a set of eddy cylinder heads....the 1.6 rocker tends to center the pushrod better in the tunnel then the 1.5...but what the hell....i guess you could not see that from your keyboard...LOL
 
OldmanRick said:
Only thing I can add is, with the 1.6, make sure you have pushrod clearance thru the head passage?
Click to expand...

I didn't mean to upset you Tony. I should have said always check. I was just trying to alert him that with the addition of several aftermarket parts, the more you should verify things. Others had already spoken of some of the different issues.
 
Screw him Rick. He's just pounding his chest like a Internet hero does.
Now if he was a real intelligent guy who actually did things instead of gloat of his one success with his one brand of rocker he would know what I'm talking about instead of poking fun at me and making false claims etc...

As anybody on this board that has done roller rockers before, they know some brands fit without issue and some do not a d will require grinding and clearancing. Use the right part the first time and you'll not know about the issues others have and will need to work.

He exposes himself in the first two sentences as someone who has little problem doing it the first time and no clue how other manufacturers parts work or not.
He regularly pokes at me. It must make him feel better.
 
AUS_Duster said:
What factors need to be considered when deciding on installing 1.5 vs. 1.6 ratio rocker arms?

I'm starting to but parts for an engine build and can't seem to figure this one out?
Click to expand...

When you figure out what lift you want to run with he head your running, you can have it custom ground with that lift. Call up a cam company and have a chat with them. The ask a bunch of questions about your car, engine, trans and rear end gear ratio, etc....

This is not a expensive option at all.
 
AUS_Duster said:
What factors need to be considered when deciding on installing 1.5 vs. 1.6 ratio rocker arms?

I'm starting to but parts for an engine build and can't seem to figure this one out?
Click to expand...


Cost, usage, and cam choice IMO. The guys touched on most of it - 1.6 will open and close the valve faster for the same given lobe. The way the get the ratio higher is they move the pushrod cup in towards the rocker shaft centerline. So depending on the pushrod, head, and lifter you may have to clearance the pushrods. Higher ratios can require heavier springs because of the lost leverage on the valve side. In terms of cams there's not much difference between a 1.5 and 1.6 - but a cam designed for 1.7 or 1.8 will be a lot different than one for a 1.5 rocker engine.
And the biggest thing - you're probably not needing to worry about it at this point.
 
The extra work and possible mistakes that come with the new choices of valve springs a d the new lift and the clearances that come with it and its just not the pushrod area I'm talking about here just simpley make the 1.5 a easier set up.

Tony was right about much of what he said but it also over looks possibilities and problems. You yourself (thread starter) have a unknown amount of skill and knowledge behind what your doing. If I made a error, consider it on the side of caution. I'd rather be safe than sorry in my advice. The KISS method is best when your dealing with unknowns. Your abilty level is one of them. No offense intended.
 
You must log in or register to reply here.
-

Back
Top