I have a stock 75 L-82 and want to install Ratio Roller Rockers. Will the heads accomodate a 1.6:1 Ratio? What kind of performance increase can I expect?

 

On a stock motor the gains will be minimal. Maybe 5 HP. You do not need roller rockers on a stock motor. Put your money into better performance upgrades. You don't need roller rockers until you start getting into roller cam spring pressure.

 

Aw, c'mon, Gordon, you're not helping the aftermarket sell anything.
You're right, but you're not helping 'em
OP: current cam manufacturers build cams for 1.5 ratio rockers to give the lift at the valve they're after. Sometimes higher ratio rockers help, sometimes they don't. Spend that money on something else, IMHO.

 

I can't document HP gains but I will throw the following out to think about:

1. I have 1.5 roller rockers on my internally stock L-82 engine since the early 90's and noticed immediately after the installation that the engine idled much smoother than with the stock stamped rockers. L-82's are notorious for not having good idle quality and the roller rockers helped this issue.

2. Just about all modern engines use some sort of roller rocker including my 94 Mustang GT and my 2001 GM 3.1 engine-there must be a reason why all these manufacturers switched to roller rockers. Hint: it is not because there is no benefit.

3. One of the reasons I put comp cams roller rockers on my L-82 was that I read 2 articles, one in Corvette Fever and the other in Hot Rod magazine prior to the intstallation that documented that with no other changes to first a C4 late 80's V8 and also an early 90's GM 3.1 V6, there were dyno proven HP gains. The Corvette Fever article claimed 20 HP on the dyno and thus you will still see today that claim for Chevy V8's in ads for roller rockers.

So, as for no advantage to them on old tech V8, I would seriously hestitate making that claim. I make this statment based on my personal experience on my L-82 and the aforementioned articles. Whether you can get 20 HP on a stock motor, I would seriously myself hestitate making that claim but I personally think that there are some real advantages.

You make the call.

 

^ not saying you don't have any real gains, but the purpose of those magazine articles is to sell stuff and the results are often doctored to make sure the claims are met. Believe half of what you read, less in car rags with sponsor's names at the end of each article
If installing a 1.6 rocker actually puts the valve in an area where flow falls off - and all production heads I've ever seen do reach that point very early - you'll actually hurt performance.
I've seen several real-world dyno tests, some increase performance marginally and some do absolutely nothing.
IF you decide to add roller rockers, make sure they're not Chinese junk. Harland Sharps are good as are Comp Cams pro magnums. The cheap ebay junk may fill your engine full of very hard needle bearings - hard enough to scuff cylinder walls and lock an oil pump down completely.

 

Let's talk specifically about what changes with full rollers, and what the benefits might be.

Ratio: The change to 1.6 from 1.5 gives a 1.067 increase to the cam lift and a change in effective (not actual) duration. If the heads can use the additional lift to provide more flow (stock heads clearly can't) then there's some associated power gain. Roller rockers will also have a more consistent ratio.

Friction: I always kind of chuckle at this one - yes, there's a reduction in friction both with the roller bearings and the roller tip...but I can't see this having measurable impact on a mild street engine.

Stiffness: This is a real benefit...if we're consistently turning > 5,500 RPM and running a relatively stiff spring with a relatively agressive cam.

Others?

Is this worth 20 RWHP? I just can't see it, but I'm willing to look at any back-to-back article with rockers as the sole change showing any real increase. Links, please.

As we're talking about this, we should be clear that this is not typically a "bolt on" operation as the valvetrain geometry changes. For example, the pushrod holes need to be enlarged on stock GMPP Vortecs.

If it was me, I'd be spending the money elsewhere...

 

I noticed a few things in my swap to 1.6 RRs.

1. Cooler temps w/AC on.
2. Engines sweet spot went up 300 rpm.
3. More quiet/smoother.

I agree this is not a first thing to change, especially on stk heads or stk
single cat exhaust. JMHO

R

 

Doing a little quick searching, this was an interesting read - it's *critical* to note the realities of the test:

"...theoretically [the cam] would not open the valves high enough with 1.5:1 rockers to even reach peak flow through the runners"

http://www.carcraft.com/techarticles...est/index.html

 

There is some thought that stamped rockers ratio (resulting in lift) may differ due to stamping process. I used Comp roller tip rockers (1.72 to 1 ratio) on my L36 (basically stock rebuild). If they helped, it was probably due to stiffer structure and more accurate ratio. Oh yeah, I have also read that roller tips do nothing...

 

Be ready to do some almost continuous valve lashing as those 'posi locks' in amateurs hands are a pain in the ***....learn the firing order and the different ways to lash the valves....You could wear a cam out in no time with out experience in adjusting valves....Your money is best served somewhere else if thats the case.....

 

I will CAUTION you on a high mileage engine.... If you install a higher ratio and your valve stems have deposits on them that gets rammed through the valve seal you will start smoking
With that said, I used the elcheapo Summit stamped roller rockers. They worked well for $70 specials!

 

 

All great points guys^. Just a couple of additional comments:

1. For $100 in 1992, I bought a set of the Comp Cams 1.52 roller rockers-cheap money regardless of the potential benefits besides what I mentioned above as well as some of the other positive observations noted above.

2. Whenever you change rockers it is very wise to change the push rods as well which is what I did at the time and recommended by comp cams. Zero problems since the change which was made on a 50,000 mile L-82 engine at the time.

3. Obviously, changing to 1.6 ratio rockers will change the valve train geometry but not in my case. A relatively easy bolt on change. No further valve train adjustment needed in 18 years.

I was actually in the valve train originally because I was getting blow by from valve stem seals that were going bad. Was it worth the change to me for $150 in 1992 for roller rockers from comp cams with new sealed power pushrods? Yes, I put on theoretically better rockers than the OEM stamped steel ones, 16 new pushrods, new and better umbrella valve stem seals all for about $150. Not a bad deal. Car runs great today and still has the original L-82 cam.

Good discussion!

 

Trying to put 1.6:1 rockers on a stock SB chevy usually results in the pushrods rubbing on the heads even with the L-82 guide plates. Make sure you check very few motors allow a straight boolt-in of these rockers.

 

Wow,

Great info!!!! I think I'm canning the idea for now since the car only has 47K.
The Winter budget will go to Headers, X-Pipe and Carb rebuild/upgrade.

 

The 1.6 rockers move the pushrods closer to the head.You have to watch that and sometimes you can't even put them on depending on what heads thay are a where the holes are located for the pushrods.