roller rocker q's

[rrubel]

I've been told by a couple sources to install roller rockers arms... Been looking at places like TPIS and finding that there are a number of sizes. Anybody have any idea what comes stock in an 86 L-98 (iron heads)? 1.5 or 1.6? 3/8 or 7/16 stud? Should I go with aluminum or steel? And any reason why TPIs charges about $130 for theirs, but Doug Rippie asks almost three times that? Are Doug's THAT much better?

Thanks...

[Ken]

Originally posted by rrubel
I've been told by a couple sources to install roller rockers arms...

Yep!

Been looking at places like TPIS and finding that there are a number of sizes. Anybody have any idea what comes stock in an 86 L-98 (iron heads)? 1.5 or 1.6? 3/8 or 7/16 stud?

1.5, 3/8"

Should I go with aluminum or steel?

Aluminum

And any reason why TPIs charges about $130 for theirs, but Doug Rippie asks almost three times that? Are Doug's THAT much better?

I have no idea.

_ken

[Jack]

For this excercise, let's pretend were dealing with a typical, stock sbc motor with stock stud-mounted, stamped-steel 1.5:1 ratio rocker arms.

One of the few under-developed areas of typical sbc is the valve train. Valve stem-guide wear often occurs well before the rest of the parts. Much of this can wear can be postponed by using roller-tipped rockers. A roller-tip rolls across the valve tip with a reduction of friction, rather than dragging across as a stock rocker does. An added benefit is that friction reduction equates to a gain of ponies.

Roller-tip rockers have bodies much like stock (typically stamped-steel) but have rollers at tips only. Full roller rockers' (having bearings at both fulcrums & tips) bodies are available in aluminum, steel and more exotic alloys.

Increasing the rocker arm ratio from 1.5:1 to say 1.6:1 increases valve lift and to some small degree (no pun intended) the duration ... as though a hotter cam were installed.

Drag racers seem to prefer full roller aluminum bodies ... endurance folk seem to go w/ full roller steel bodies (good ones have an "effective weight" comparable to aluminum).

I suggest that a stock motor will benefit very little with 1.5:1 roller rockers ... the valve stems & guides'll get some friction/side-loading reduction (longer-lasting valves-guides) ... MAYBE some small increase of power. IMHO, I wouldn't bother with them for a stock motor. For about the same money get a mild cam, lifters & timing set ... with more noticeable effect.
JACK

[jerrys96lt4]

In the past Id always put 1.5:1 on the intake And 1.6:1 on the exhaust. The exhaust design on a sbc needs a little help.
my .02 Got to go with aluminum-lite weight-super strong.

[rrubel]

Thanks; good info all.

So if the stock engine has 1.5's, it's suggested to go to 1.6's? Or split between the intake and exhaust?

I'm not doing the cam right now because from what I can tell the rockers are something I can do myself without pulling the engine but the cam I cannot. Correct?

On the aluminum vs steel, TPIs states that the aluminum is lighter, therefore giving more HP, but the steel is strong enough to give another 300 RPM - and RPM is power, usually.

Thanks much!

(you know, with all these clickable smilies, I'm surprised there isn't one for driving... you know, sawing a steering wheel back and forth and grinning evilly)

[RICHR]

[bradfordsvettes]

not sure on your engine but on some of the small blocks if you use 1.6 arms the pushrod will hit the back of the head at the slot in the head for the pushrod best to check and see if you would need to clearance that area when installing them steve

[vettepilot]

There was a great article several years back on roller rockers, (and I can't remember the publication) they were working on an otherwise stock 92 or 93 LT1. Dyno runs were made as the work progressed, first using 1.6:1 on the intake retaining 1.5:1 on exhaust, someHP was gained. Then they reversed the setup, about the same amount was gained. The 1.6:1 on both the intake and exhaust, a solid 25HP gain, can't remember the TQ gain. For the money, that's a pretty good gain, and it's across the entire power band, not just at WOT like most bolt-on's or chips.
Stan

[69MyWay]

I run them whenever I can, that is full roller rockers.

There is a reduction in friction and weight with an aluminum bodied rocker.

However, you need push rod guides, hardened push rods, and either valve cover modifications or different covers.

For a street car you can get away with the cheaper versions because the car won't be living at redline for minutes at a time.

I think the best ones to ge are those that G.M. built and sells for the LT4 engine. These self align on the valve stem and don't need push rod guides. They will fit under the cover no problem. They will set your wallet back as well about $400. However, for the money you can't beat them. My buddy put a set on his 85 and they are sweet.

I think in the perfect world under the perfect conditions a good lightweight set of full roller rockers will get you 25 more hsp.

[Ken]

There's a blurb in this month's Corvette Fever new products review page on the new Jesel SS Roller Rockers. It says they are shaft-mounted to the original bosses for a solid foundation and eliminate the need for guideplates.

_ken