Roller Rockers

[l98vette1986]

I just bought a set of new Harland Sharp Roller Rockers. My question is, has anyone had any evident dyno proof of an increase. i went w/ 1.5's so i wouldnt increase valvetrain stress, and b/c i already put a bigger cam in, and dont need the extra lift. While looking at the old rockers i noticed that for 100,000 miles they didnt have much wear, meaning that they obviosly do not cause as much friction as people think. I'm sure they dont put out the 15hp that they are advertised at. Any feedback would be appreciated.

 

[Redbob]

Regarding roller rockers, one theory often mentioned is that they are stiffer than the original stamped steel rockers, and therefore will give the full theoretical valve lift even at higher RPM, giving a slight edge in horsepower.
Some folks have tried to document that advantage, but I'm not so sure they weren't documenting their test variability instead.

My own experience suggests that any dyno differences less than 2% - 3% should be examined very closely before making any claims about them.

Regards,
Robert

 

[l98vette1986]

well, i put them on tonight using the 2 rotation methid, and ofcourse i can feel no difference, but i guess when you have already done EVERY thing else its hard to tell

 

[Hib Halverson]

Roller rockers, of the same ratio as what was on the engine originally, will never offer an increase in performance unless you they are installed on an engine running some high rpm. Typically this is 6000 rpm or higher.

Though it's not listed in the lead post in this thread, my guess is these Sharp roller rockers are on a stock or near stock L98. As L98s are through at 4800 or so rpm, roller rockers are perhaps unnecessary on this engine.

It is true that stock rockers tend to "bend" but the flexing is only a problem at high rpm and with high valve spring pressures. The amount of rocker flex in a stock or near stock L98 will be negligble.

Another issue is that stock rockers tend to be a little less than 1.5:1. Many times stockers will be 1.46-1.49. While that can be measured with the proper equipment, in an L98 that's stock or near stock, 0.1-0.3 of the rocker ratio is going to make such a small difference you'd be hard pressed to see it on any dyno.

You've got the Harland Sharps now, so enjoy them but a fresh set of OE GM rockers would have worked just as well and been quite a bit cheaper.

 

[l98vette1986]

Well, if you must know, i have Edelbrock performer heads, a crane single pattern Flat tappet Cam w/ .470 lift, and 226 duration, and the mini-ram intake. Hooker Supercomp Headers w/ true duals, and a lot more.. this is no stock tuned port, and i generally turn it to around 6,500 for best performance. But i really apreciate the follow up, i'll advise my stock friends to just go w/ stamped steel.

 

[69MyWay]

Well, if you must know, i have Edelbrock performer heads, a crane single pattern Flat tappet Cam w/ .470 lift, and 226 duration, and the mini-ram intake. Hooker Supercomp Headers w/ true duals, and a lot more.. this is no stock tuned port, and i generally turn it to around 6,500 for best performance. But i really apreciate the follow up, i'll advise my stock friends to just go w/ stamped steel.

Cool! It sounds like we are running some similar equipment. I too have the RPM heads, a Crane hydraulic roller cam, mini ram intake, 52 mm TB, headers, and yes, full roller 1.5 rockers.

Do they add any power.....I don't know, but it sure is nice to know they are in there pumping away reducing friction, and helping the engine roll along easier.

Your 100,000 mile rockers were in good shape...because...I would bet you or the previous owner(s) changed oil often and took decent care of the motor.

I have replaced dozens of standard stock stamped steel rockers over the years that came out of motors with less miles that had been neglected. I have seen where the push rod has actually punched through the tip, and where the inside cup is so worn that it is paper thin and razor sharp around the edge when removed from the head.

What kind of performance statistics do you have for your motor?

 

[l98vette1986]

I took my car to the track when it had stock exhaust, and the Lingenfelter super ram w/ a stock ported manifold base at a corvette show and drag. I came off the line sideways (hard street tires) i hooked up half way through 2nd, and and pulled one car lenght on the C-5 that ran 8.52. On that pass i ran 8.47 at 87mph on the 1/8th. My second pass i broke a slider for 1st, and second gear going indo second, so i put it in 3rd, and ran 10.70 at 65 mph. (lost that one). It's no field trip getting parts for a 4+3, so i used one from a T-10. Now i am certain things are different, and i am very anxious to see what it is gonna do w/ slicks. That was about 2 months ago, and as soon as i get a bigger fuel pump, and a little better ignition system i'll be back out to stomp some mustang A--! Whats your e-mail address, i'll send you a burnout pic.
Later
Chris

 

[69MyWay]

chrisnikki@juno.com

 

[Hib Halverson]

A highly modified L98 such as was described in more detail, will benefit from roller rocker arms.

 

[Edmond]

Well, if you must know, i have Edelbrock performer heads, a crane single pattern Flat tappet Cam w/ .470 lift, and 226 duration, and the mini-ram intake. Hooker Supercomp Headers w/ true duals, and a lot more.. this is no stock tuned port, and i generally turn it to around 6,500 for best performance. But i really apreciate the follow up, i'll advise my stock friends to just go w/ stamped steel.

AWESOME!!!:BOW

 

[69MyWay]

Nice burn out pic! Thanks!

 

[Vettelt193]

I disagree with the statement that a stock 'Vette won't benefit from roller rockers.... If they are installed properly, there is a big advantage in both power gains and cooler oil temperatures.... If there wasn't that much friction with the stock rockers then the oil temp. change would be hardly noticable, but, the oil temp will be noticably cooler with the full roller rockers....

Also, Full roller rockers is one of the only mods you can do that has no negatives.... more HP, better gas mileage, cooler oil, etc....

 

[vms4evr]

Does anyone know where I can get the split set. 1.6 intake / 1.5 exhaust. I was told that is a good mod on an LT1 and you do get a little HP improvement plus the benefit of rollers. I'm also curious that they did not mention changing the springs on the 1.6 side. As I recall a jump from 1.5 to 1.6 requires new springs? Comments?
Graham

 

[l98vette1986]

TPIS sells a set of 8, that way you can mismatch them

 

[l98vette1986]

...and you will need stronger valve springs
Not trying to be a tpis salesman, they sell them too.

 

[69MyWay]

...and you will need stronger valve springs
Not trying to be a tpis salesman, they sell them too.

TPiS has some great stuff. They are one of my favorite C4 peoples.

 

[Vettelt193]

The LT1 only needs valve springs if you go with the full set of 1.6's (and even then it is only sometimes) If you go with the mixed set, put the 1.6 on the intake, 1.5 on the exhaust, and save your money on the springs... I have run the split set on an LT1 and I found it to be the best combo. for it... You don't lose torque on the bottom, but gain some on top, and since you reduce friction all around, you get better gas mileage, cooler oil, and more power through the whole power band

 

[johnny]

I have dyno results

I have crane rolle rockers goldseries 1.5 installed, and the is no change in bottem power, but a slightly increase at top end power. Depending how your setup of your engine is, I would say 10 till 15 hp at 5.500 rmp.

 

[Mako]

...and you will need stronger valve springs
Not trying to be a tpis salesman, they sell them too.

The need for new spring when installing 1.6:1 rockers on an LT isn't amatter of strength (which I assume you are equating with seat pressure), rather it's a matter of avoiding coil bind.

Stock LT1 springs come very close to binding when running 1.6:1 rockers. If the spring does bind, it will eventually fail. Been there, done that my self.

Here's one way to run the necessary spring setup from the Bay Area F-Body home page at: http://www.ba-f-body.org/index.htm

"
Running the Crane 99846 spring on an LT1/LT4 head

Got the answer folks!

Get 16 of GM part nos. 1018-5066. It is the L98 seat/shim. It has the same id as the LT1 seat/shim but has a much narrower guide on the id so that the Crane 99846 spring/damper combo will fit perfectly. The LT1 seat has a wider guide on the id since the stock springs are damperless. The part is 0.85$ each dealer cost. So for less than 16$ you are good to go with the trick 99846 Crane springs.

They bind at 1.100 inch and should be installed at 1.750 or so to get about 115#s of seat pressure. I am using the L98 seats which are 0.030 inches thicker than the LT1 seats and a 0.030 inch shim to get 1.740 inch installed ht.

Voila, no damper bind! And an easy (at 1.740 installed ht) 0.590 inch of lift at the valve available. That should work for most of the cams we use even with 1.6 rockers. (don't forget the valve guides need to be cut down a bit if you are using this kind of lift).

Perry Kincy
"

Good luck!
Mako