?

I know the roller tipped ones do, but just started thinking about going full roller.

 

You will have to narrow (crush with ginormous pliers or something) the "tube" things that the bolts go through. Unless of course you use the old narrow-body Crane ones that GM used to sell, which since they are/were narrow, and are/were aluminum, are/were somewhat less reliable than … good ones. No clue whether those are still available. Wouldn't want em even if they were, personally.

 

All I know is that I've seen lots of narrow body, self aligning rockers that supposedly fit stock L98 heads with visible wear marks from rubbing. My personal experience was that the valve tips didn't extend far enough past the top of the valve spring retainer to reach the roller tip of the rocker. In other words, the body of the rockers would hit the retainer before the valve would touch the rocker.

So then I looked at dumping the stock retainers, rotators, springs, etc and going to an aftermarket spring. Long story made fast and dirty, it couldn't be done without having the heads machined. Had I known that to begin with, I'd have saved the money spent on rockers, springs, retainers, keepers, seals, and the time to tear it all apart, take measurements, and research the issue in depth. Huge waste of time and effort.

Fitting the stock valve covers was the least of my worries.

 

Thanks guys

 

I had to remove some material from the "rib" (that passes through the centreline of the supporting tube) so as to allow clearance for the rocker trunnion. Can't comment on any other interference regarding the OEM bits as I'd made the move to a small diameter valve spring. Easy job though.

 

If you use the right rockers they will, I have done several.

 

I have a set of Scorpion narrow body rockers on my Vortec heads that the bolt tubes clear no problem. And my truck with vortec's has some of the older Crane narrow body units that have over 10k miles on them.

GD

 

X2 on them working. I have 1.6 ratio Scorpion's on my L98 with 113 Vette heads and stock L98 valve covers no issues with the rocker tips or the sides of the bodies.

 

Thanks again,

I spent some time googling the Scorpions, all seems favorable.

Odd that in searching CompCams rockers came up hit or miss.

Sofa (if you are still looking at this thread) you used to be a big Comp supporter, have you heard of any QC or changes over the past years?

 

The Scorpion rockers are US made and very nice quality. Good instructions and packaging too.

Not all that impressed with Comp unfortunately. There's a lot of better options IMO.

GD

 

I have no recent personal experience based knowledge from Comp any more. No family members or roommates any more that work there, haven't done any work for them myself in decades.

They are a YUUUUUUJJJJJJJE supplier to our hobby though; so like anybody, even if there are only a tiny fraction of buyers that have trouble of whatever kind, you hear about it ALOT. It seems like a big deal but as a proportion, … hard to say.

The objection I have to the GM (Crane) or Scorpion narrow-body rockers has NOTHING to do with "quality". Both Crane and Scorpion have been making things of that sort, much as Comp has, for several generations of humanity by now. The problem with those is, THEY'RE ALUMINUM. Aluminum parts of that kind DO NOT belong on the street. As I've posted before, if you take a REAL FAST car, let's say, 10 seconds flat, that crosses the finish line at 7200 RPM with a 7200 RPM converter (just to keep all the numbers simple), that means that during that run, the motor ran 7200 RPM for 10 seconds. 10 seconds is 1/6 of a minute; that means the CRANKSHAFT turned 7200 ÷ 6 times, or 1200. The rockers each moved ONE HALF of that many times; 600 reps. 600.. Now of course, you had to stage it, idle a bit, do a burnout, cruise back down the return road, … let's say it turned 600 more times doing ALL THAT. Probably didn't, but w/e. You run this car a full season of racing; what, 20 weekends or something? You average, what, 3 rounds a weekend? That's 1200 reps on the rockers per round, or 3600 per weekend, or 72,000 per a whole season. After that, you probably tear it down and inspect. OK, let's compare to your commute. Again, to keep the #s simple, we'll say your car cruises down the freeway at 2400 RPM, and it takes you 15 minutes each way; 30 minutes round-trip. OK fine, that's 2400 RPM for 30 minutes PER DAY then, which is … 72,000 reps on the rockers. NOW: do you want to tear down and inspect your rockers EVERY SINGLE DAY??? Not no; HELL NO. So you drive it for, let's say, a month; 22 working days average per month. That's now over ONE AND A HALF MILLION reps on the rockers PER MONTH. On a part that was designed to run maybe 250,000 reps IN ITS LIFETIME. You put the equivalent of 22 racing seasons on your rockers EVERY MONTH.

That's why aluminum rockers are a bad idea on the street. The material suffers from a failure known as "fatigue"; it is somewhat unique to aluminum, and all A&P mechanics are familiar with it. It's why airframes have to be TORN COMPLETELY DOWN, all paint stripped, and inspected, every however many take-off/landing cycles, hours of operation, or whatever; and why certain parts have to be REPLACED every however often. Not "inspected"; not "tested"; not not not not not not. REPLACED.

Why would ANYBODY in his/her right mind put something like that in his car???

 

Sofa speaks the truth here , if anyone wants a scary lesson in metal fatigue do a google search of "Aloha Airlines Flight 243" , It lost the top of the fusalage from just behind the flight deck and extending back beyond first class at over 20 thousand feet , and actually managed to land safely afterward . One person , a flight attendant , was sucked out of the open roof and was killed . I'm a big believer in the right metal for the right job and keeping a good eye (and ear) on all things mechanical .

"The National Transportation Safety Board determines that the probable cause of this accident was the failure of the Aloha Airlines maintenance program to detect the presence of significant disbonding and fatigue damage which ultimately led to failure of the lap joint at S-10L and the separation of the fuselage upper lobe. Contributing to the accident were the failure of Aloha Airlines management to supervise properly its maintenance force; the failure of the FAA to require Airworthiness Directive 87-21-08 inspection of all the lap joints proposed by Boeing Alert Service Bulletin SB 737-53A1039; and the lack of a complete terminating action (neither generated by Boeing nor required by the FAA) after the discovery of early production difficulties in the B-737 cold bond lap joint which resulted in low bond durability, corrosion, and premature fatigue cracking."

 

I've often spouted off about aluminium rockers in a street application but for whatever reason their popularity still exists.

I can only blame the masses watching YouTube and monkey see, monkey do.
Now how about a nice set of Carrillo aluminium connecting rods for you hot daily driver....

 

So, now talking roller rockers for the street and longevity, what are the options, or are there any? I assume a cast steel, certainly not a forged product. Heck, when I was running 385 series Fords, we used DoVE heads with casted steel rockers and they lived to 6500, and never had issues

 

That's the funny part of it. Plenty of folks have used aluminium rockers to 6500 RPM and never had issues either. At least we don't hear about them anyway. But metallurgical facts are facts. Aluminium fatigues.
As for a full roller rocker, I had gone with COMP in the past due to price point and availability. Several years back they changed their model line up and prices went up. That said, I had to make the move to a backset trunnion due to the .100" longer than stock valves (long story). I was forced into the only available product at the time and that was Crower stainless offering. The price was steep but then it's cheaper than another valve job because the geometry was so far off otherwise.
Doing a quick run through Summit's catalogue and prices range (for a set of 16) from 150 bucks for Speedmaster (who they are I have no idea and I'll pass thanks), the PRW at about 300 through to COMP's at about $400 up to the Crower's at nearly 700.
All steel/stainless steel. Various ratios and stud sizes.
Prices may vary....

 

Eh..... times change and material science brings new alloys, etc.

Googling around a bit and looking for failures on the Scorpion rockers yields basically nothing. Some early 1.7 LS rockers with incorrectly sized pushrod cups which Scorpion replaced back in 2008....

Not much to be seen other than a LOT of people running them without problems.

Pistons are aluminum also. Not really seeing problems with anyone ripping the wrist pins out the bottom.

Casting alloys with high silicon content..... aluminum is pretty tough stuff.

I think the fears that may have once been a fair concern are largely outdated. I'm just not seeing the evidence for this in the last 10 years or so.

Just my opinion though.

GD

 

Pistons don't get the same kind of stress put on them that rockers do, such that they tend to bend. Fatigue doesn't apply to them.

For every aluminum rocker user that's run them for a long time on the street, there's at least one other user that's had at least one break. I've known plenty myself, covering just about every major brand. It's one of those things that just because "all the fast cars" use them, doesn't translate well to the street. Fine for the strip, where the sheer number of repetitions of stress (operating cycles) is so much lower, because the time the engine is running is shorter; not so good for the street.

The Crower stainless rockers are a really nice piece. So are the better Comp ones. Interestingly enough, because of the shape that has to be used to bear the load, aluminum ones end up with as much rotating inertia as stainless ones if not more, because so much of their weight has to be out near the tip.

No idea who Speedmaster is either.

 

Crane is pretty clear in their catalogue that the full roller aluminium body rockers will NOT clear centre bolt valve covers.

 

elgin makes a nice budget full roller rocker. stainless steel body. about 159.00 a set. the 1.5, and 1.6 sets for 3/8" studs are pretty cheap. and better quality that most would guess.

 

Sounds suspiciously like a chinesium knockoff.

Not that the Chinese "can't" make good stuff; only, that the usual reasons that things are made there, are (a) to minimize cost aka "keeeeeep it cheeeeeep"; and (b) they have ZERO intellectual property protection, meaning anybody can take anything and COPY it, and not be obligated to pay the person who THOUGHT IT UP in the first place and did all the research and other work to develop it into a viable PRODUCT, aka STEAL it.

And there are 2 REAL GOOD reasons to avoid sending ANY money to that country; (a) the Chinese Communist Party, and (b) the Red Army. I have no desire to participate in financing and enriching either of those organizations. (though actually they are arguably the same thing)