Roller Rockers 1.5 vs 1.6

-
DentalDart

DentalDart

FABO Gold Member
FABO Gold Member
Joined
Jul 5, 2019
Messages
5,560
Reaction score
5,242
Location
Ozark Missouri
How do you decide on which ratio to get?

I didnt get any when I purchased my aluminum heads but now SM has all the SS rockers in stock ( well kinda...) so since they haven't had any in 7 months I think I may pick up a set... I kinda want 1.6 for a little "extra" lift from my cam but worry about valves hitting pistons?

Build...
30 over 340, pistons all around .012 out of the block
Xe268h camshaft
SM CNC fully assembled heads (pictured)

I know I know buy the expensive ones that are "better..."

Screenshot_20220529-194852_Samsung Internet.jpg


Screenshot_20220529-194706_Samsung Internet.jpg


Screenshot_20220529-194738_Samsung Internet.jpg
 
Which pistons, and .477/.480 lift? What rockers are you running right now? Use a piston stop to verify and put number one to TDC, remove the rockers and valve springs, install checking springs on number one, and measure the lift amount where your valves meet the pistons. Comp can take those measurements and tell you how much rocker ratio will work. Most shelf pistons with generous valve reliefs won't have any trouble with .509/.512 lift with only .012 out of the hole. But I doubt you'd even notice any difference between a set of 1.5 and 1.6 rockers. If I had the gear and converter, I'd do the measurements and see if I could switch up to a comp XE solid cam. IF you can find one anywhere, though. You might would have to go with Ken at Oregon Cam Grinders to get a solid cam in a reasonable time frame. He has his own versions that are somewhat similar but with his own improvements on them. I guess I should ask, is it together and running yet or are you still in the assembly stage?
 
Last edited:
Garrett Ellison said:
Which pistons, and .477/.480 lift? What rockers are you running right now? Use a piston stop to verify and put number one to TDC, remove the rockers and valve springs, install checking springs on number one, and measure the lift amount where your valves meet the pistons. Comp can take those measurements and tell you how much rocker ratio will work. Most shelf pistons with generous valve reliefs won't have any trouble with .509/.512 lift with only .012 out of the hole. But I doubt you'd even notice any difference between a set of 1.5 and 1.6 rockers. If I had the gear and converter, I'd do the measurements and see if I could switch up to a comp XE solid cam. IF you can find one anywhere, though. You might would have to go with Ken at Oregon Cam Grinders to get one in a reasonable time frame. I guess I should ask, is it together and running yet or are you still in the assembly stage?
Click to expand...
Sharp, clear, and, concise.
 
Correction: Earlier, my search through Summit Racing didn't show anything available until August. Here are the solid cams that are "supposedly" available directly from supplier. I personally like 20-230-4 in a hot street build, but I don't remember the specifics of the rest of your car combination and goals.
DODGE 5.6L/340 Mopar small block LA Camshaft Kits Camshafts & Valvetrain Engines & Components - Mechanical flat tappet Cam Style - In Stock Filter Options - Vendor In Stock Filter Options - Camshafts Part Type - Free Shipping on Orders Over $99 at Summit Racing
 
Garrett Ellison said:
Which pistons, and .477/.480 lift? What rockers are you running right now? Use a piston stop to verify and put number one to TDC, remove the rockers and valve springs, install checking springs on number one, and measure the lift amount where your valves meet the pistons. Comp can take those measurements and tell you how much rocker ratio will work. Most shelf pistons with generous valve reliefs won't have any trouble with .509/.512 lift with only .012 out of the hole. But I doubt you'd even notice any difference between a set of 1.5 and 1.6 rockers. If I had the gear and converter, I'd do the measurements and see if I could switch up to a comp XE solid cam. IF you can find one anywhere, though. You might would have to go with Ken at Oregon Cam Grinders to get a solid cam in a reasonable time frame. He has his own versions that are somewhat similar but with his own improvements on them. I guess I should ask, is it together and running yet or are you still in the assembly stage?
Click to expand...

I currently have the Comp Cams XE268H pic of specs below, so yess .477 / .480 lift.
Pistons I forget which ones, some basic .030 pistons in a 340.
Heads are the speedmaster cnc heads pictured above.
Stock steel rockers
Quick fuel (holley) 750
Headers
2.5 exhaust
904 with shift kit
3500-3800ish tight converter
3.23 gears and sure grip

Car is together and running. Although I tend to take stuff apart every month or so to add something new lol. Goals? Meh no big goals, just like tinkering, adding new parts and having fun... oh and goofing off in the car with my partner in crime. Eventually will build the new motor and get bigger tires...

Screenshot_20220530-001909_Samsung Internet.jpg


20220515_113823.jpg


20220513_162246.jpg


20220529_103923.jpg


20220529_154104.jpg
 
I'd call b3 and get some input and suggestions.
A 1.6 will increase lift, which is good, but it can also amplify any potential issues you have with the valve train, and so proper spring choice and geometry is important.
Plus, B3 has extensive experience with lots of different combos and can probably help point you in the right direction.
His geometry correction kits would be worth it IMO.

Fwiw, I run stainless 1.6 rockers in my tfs heads and so far so good.
 
Phreakish said:
I'd call b3 and get some input and suggestions.
A 1.6 will increase lift, which is good, but it can also amplify any potential issues you have with the valve train, and so proper spring choice and geometry is important.
Plus, B3 has extensive experience with lots of different combos and can probably help point you in the right direction.
His geometry correction kits would be worth it IMO.

Fwiw, I run stainless 1.6 rockers in my tfs heads and so far so good.
Click to expand...

What cam do you run?
 
DentalDart said:
What cam do you run?
Click to expand...

Right now it's a hydraulic flat tappet. Comp xe295. 408 Stroker shortblock.
With kb dish pistons (I believe kb356 with some of the top of the step milled off) I had about .090" piston to valve clearance. I think it was actually much more, but I was using .090 as a guideline and just compared.
 
1.6 rockers will increase effective duration 2-3*. Doubt you will feel the difference. I would only buy new rockers if the existing rockers need replacing.
 
Any extra lift you can get going to a higher rocker ratio is a plus in my book..
 
Get the lift with the cam, or get a smaller cam and augment it with the 1.6's. Just make sure your valve train geometry is as good as you can get it. JMO. Paul.
 
You don't want to buy those 1.6 rockers anyways. There's a marked quality difference between the 1.5 set with the steel hold downs (this set is sold by other vendors like PRW) and the 1.6 with aluminum.s

The 1.5 steel hold down set has bronze bushings and the machine work on the rockers and hardware was decently done. They were a little gritty, but after a cleaning all the threads checked out good and the rockers fit well on the shafts.

The 1.6 aluminum set are also bushed, but using iron/steel bushings. They weren't reamed as well and didn't fit the included shafts properly. The threads in the arms were poorly done and needed chasing, and the oiling holes in the adjusters themselves were drilled off center on a few parts.

Same factory, but likely made to different quality requirements and SM buys the excess stock on the higher quality parts. PRW sells those same 1.5 rockers for $400+.
 
DentalDart said:
I currently have the Comp Cams XE268H pic of specs below, so yess .477 / .480 lift.
Pistons I forget which ones, some basic .030 pistons in a 340.
Heads are the speedmaster cnc heads pictured above.
Stock steel rockers
Quick fuel (holley) 750
Headers
2.5 exhaust
904 with shift kit
3500-3800ish tight converter
3.23 gears and sure grip

Car is together and running. Although I tend to take stuff apart every month or so to add something new lol. Goals? Meh no big goals, just like tinkering, adding new parts and having fun... oh and goofing off in the car with my partner in crime. Eventually will build the new motor and get bigger tires...

View attachment 1715934994


View attachment 1715934995

View attachment 1715934996

View attachment 1715934997

View attachment 1715934998
Click to expand...


.477 lift with a 1.5 rocker is .508 with a 1.6. ( lift divided by 1.5 X 1.6) .480 is .512 with a 1.6
 
Bewy said:
1.6 rockers will increase effective duration 2-3*. Doubt you will feel the difference. I would only buy new rockers if the existing rockers need replacing.
Click to expand...

Mine only need replaced because I have an itch and they are stock...
 
TurboGLH said:
You don't want to buy those 1.6 rockers anyways. There's a marked quality difference between the 1.5 set with the steel hold downs (this set is sold by other vendors like PRW) and the 1.6 with aluminum.s

The 1.5 steel hold down set has bronze bushings and the machine work on the rockers and hardware was decently done. They were a little gritty, but after a cleaning all the threads checked out good and the rockers fit well on the shafts.

The 1.6 aluminum set are also bushed, but using iron/steel bushings. They weren't reamed as well and didn't fit the included shafts properly. The threads in the arms were poorly done and needed chasing, and the oiling holes in the adjusters themselves were drilled off center on a few parts.

Same factory, but likely made to different quality requirements and SM buys the excess stock on the higher quality parts. PRW sells those same 1.5 rockers for $400+.
Click to expand...

I want the 1.6s with the steel hold downs, but they are not in stock right now... maybe they will be in the next week or 2. I'm in no rush, just need something to tinker with on the car. Everything else I want to do costs to much money.

I have seen that these rockers are essentially the same exact ones as the PRW which is why I will buy these instead of PRW, at 1/2 the price. Plus I have a friend who has the SM on multiple motors and they have been good to him.
 
Had a similar convo with myself last year. Bought a set of Promaxx AL heads and was going to replace the stamped rockers on my 360 LA anyway. Mild cam in my whip is a CC 268H.. .450~.450 so going to 1.6 ratio still puts me well under 1/2 inch lift... I picked up a set of Harland Sharp 1.6 rollers off Mancini.

Unless you are going to run into interference issues... why not?
 
Peak valve lift has nothing to do with valve to piston clearance.

Where is the piston when the valve is at full lift?
 
You’re missing the point completely

I’ll help the thought process.......
The xe268 cam has an lsa of 110.
Let’s say you install it at 106.

Where are the crank/pistons when the valve is at full lift?
 
PRH said:
You’re missing the point completely

I’ll help the thought process.......
The xe268 cam has an lsa of 110.
Let’s say you install it at 106.

Where are the crank/pistons when the valve is at full lift?
Click to expand...
About half way down the cylinder.
I check v to p clearance at least 15° on either side of TDC, for intake and exhaust....
 
33IMP said:
About half way down the cylinder.
I check v to p clearance at least 15° on either side of TDC, for intake and exhaust....
Click to expand...
Exactly. I thought we were talking about valve to piston clearance (or lack of) if the OP uses 1.6 rockers instead of the stock 1.5's. May be I missed something in the middle.
 
Duration is what causes valve to piston contact not lift. Max lift is not a concern. Guys listen to @PRH here. And @DentalDart you measure for P to V at split overlap around 10-15 degrees + or - not at TDC compression.
 
You must log in or register to reply here.
-

Back
Top