I am interested in replacing the stamped steel rocker arms (1.7:1 ratio) on my 1966 425hp big block with the aluminum roller rocker type. This is new to me and I would like feed-back to the following questions: 1) Do I simply take off the stamped steel arms and replace them with the new aluminum roller rockers? Are there other issues/variables I should be cognizant of?; 2) Which aftermarket source for the roller rockers would you recommend, someone like Crane Cams, Competition Cams or others?; 3)After I install the new roller rockers I assume that the value lask will have to be re-set. I understand that the best way to do this is with the engine warmed-up and running; As such, I assume that I would do one clylinder head and then the other. In doing this, would I do all the intake values in the row and then do the row of exhasut valves? Any helpfull hints on setting the valve lash? Thanks for the help.
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Re: Rocker Arms
John-----
Replacing your existing stamped steel rocker arms with roller rocker arms is a relatively straight-forward process. You simply remove the lock nut at each rocker arm, remove the rocker arm and ball, and install the new rocker arm on the existing stud. Roller rockers must be retained by set screw type locking nuts which are usually supplied with most good aftermarket roller rockers. This is due to the fact that there is not sufficient clearance for a socket wrench within the rocker arm body. Generally, most of these type lock nuts will work acceptably with stock rocker studs. Sometimes, however, if the tops of the rocker studs are particularly irregualar, you may need to grind them flat or install aftermarket studs which are already ground flat. Replacing the studs with a set of high quality ARP studs might not be such a bad idea anyway.
The only installation difficulty that you might encounter is possible interference of the rocker arm/nuts with the drippers installed on the inside of your valve covers. If there is interference, you will need to grind off or bend over the drippers. Otherwise, most roller rocker arms will fit under stock big block valve covers.
Personally, I prefer stainless steel roller rockers to the aluminum variety. Aluminum work hardens and fatigues over time in such a high stress application. However, Chevrolet did a lot for the credibility of aluminum rockers in my mind when they were validated for use on PRODUCTION 1996 LT-4 small blocks. In any event, I still prefer the stainless variety manufactured by Crower or Comp Cams. If you go with aluminum, I'd recommend Crane, Iskendarian, Crower, or Comp Cams.
After installation of the rockers you will definitely need to readjust the rocker arms. For your solid lifter engine I'd recommend first using the static adjustment procedure outlined in your Chevrolet Service Manual. Then, after starting the engine and running it up to operating temperature, "fine tune" the adjustment with the engine "hot and running". For the pre-adjustment you will need to have your engine in the various firing positions specified in the service manual when you adjust particular valves. For the finish adjustment, though, you can just move from one valve to the next on each side. You will, of course, require oil deflector clips to perform the "hot and running" adjustment. Even then, you'll likely get more than a little oil outside of the engine. If you wish, though, you can do all of the intakes on one side, then the exhausts so that you don't have to keep switching feeler gauge blades. The adjustment order for the "hot and running" adjustment is not important at all.In Appreciation of John Hinckley -
Re: Rocker Arms
Sounds like high school stuff to me. Stamped steel rockers are fine if not galled and lubed properly. What do you hope to accomplish with this change?
VarooomComment
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Re: Rocker Arms
Dale---
I used to think so, too. At least I did until GM started using them on the 96 LT-4 engine and continued using a version of the roller rocker arm on the new LS-1 engines. I figure for GM to spend the money that this change costs them for an UNSEEN component of the car, they must have figured out that something REAL POSITIVE comes with the use of roller rocker arms.In Appreciation of John HinckleyComment
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Re: Rocker Arms
What they figured out was that a whole new set of rules exist for meeting government mandates on emissions, milage, etc.etc. I still would like to know what real advantage roller rockers offer for street use.(especially on a 35 year old engine design.)
Varooom.Comment
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Re: Rocker Arms
Dale, I started using them several years ago. Found it easier, more accurate to set my valves w/engine running and as Joe said clips in place. My only gripe was those aluminum nuts they came with coming loose after prolonged use (racing) and running at high RPMs. No problems with stock v/v cover drippers. I recommend changing the "nuts" out completely if you ever have them off for some head work like I did. That was my main problem.Once they are on the stud and you remove them they loose their conformity or shape and become round and will come loose.I was using CRANE stock rockers with roller tips. But if the writer isn't going to race I wouldn't waste my money. Stay stock. Regards GRR#33570.Comment
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Re: Rocker Arms
My driver uses a set of hand-made shaft mounted stainless steel rocker arms with roller bearings on the shaft and roller tips as well. Been runnin em about 12 years. They are damn reliable and with the cam Earl Gerte picked out for me I could get 8000 rpm with no problem. Trouble was that in order to leave a stop light at less than 4500 rpm I had to slip the clutch. Spending all those bucks for an aluminum sprint car motor in a 62 Corvette was one of the dumbest things I ever did in my entire life. I would gladly trade the shaft mounted rocker arms for stamped steel any day. (If you wanna give me back the $2,500.00 I spent on them.) They are a pleasure to adjust and hold their adjustment well. Trouble is that they are worthless on a street driven car.
I set my lash with the engine off and cold. The exhaust is gonna grow about 0.003 thousandths and the intake about 0.002 so I adjust the hot specs accordingly I've got the balancer marked at o, 90, 180, and 270 degrees so a socket wrench on the balancer nut makes this job easy. With the plugs out it's a snap. By the way, NASCAR sets lash the same way, COLD!
Varooom!Comment
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Re: Rocker Arms
Dale - roller rockers reduce internal engine friction. This increases power, but the real motivation for the OEMs is fuel economy since most are running at or near the limit of CAFE and are subject to big fines if they bust the numbers. Hydraulic roller lifters also save on internal parasitic loses. These and many other small changes, which have evolved over the year are why the new LS1 is more efficient and delivers better EPA fuel economy that the LT1 despite a nearly 15 percent increase in peak power.
DukeComment
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Re: Rocker Arms
So why would a man with a 35 year old engine design want roller rockers? What is he going to gain for the money? Roller TIP rockers are a joke! Supposed to reduce friction but the AMOUNT of friction reduced is almost unmeasurable. Roller trunion bearings save a little more energy but again almost unmeasurable.What the heck, stick em in! Afterwards, buy a PREDITOR carburetor to complement a magnum cam with a street fighter auto and the whole package will be a "sleeper" good for "streeet/strip" stealth operation! HA! Chances are 99.9% it won't get out of its own way!Comment
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P.S. I got a set of Harlan Sharp I ain't using
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Re: Rocker Arms
Dale, can't agree more. Sounds like you have your act together.The last thing I want to do "again" is leave parts at an intersection like I did when I was a kid.It's bad enough to trailer out of the track as fast as you can to avoid having to say "I blew up whatever". I'm presently about 6 weeks from completion on a stock 67 coupe, L-71. To many original parts to part with or modify. Even though I have trouble passing by my Summit racing catalog. But this one I'll leave alone. A couple tuning tricks for the street and sunoco 130 are good enough for around here. Best Regards GRR#33570.Comment
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Re: Rocker Arms
Theoretically, roller rockers should free up a little bit of power, particularly on a high-revving engine, but the improvement (0-2 percent) is tough to measure on a dyno because it's within the range of dyno test repeatability. Then again, sometimes we just sleep better at night knowing that we've treated our antiques to a new-age hi-tech gizmo that the judges can't detect.
DukeComment
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Re: Rocker Arms
Dale-----
I suspect that they reduce internal friction just about as much in the 35 year old engine design as they do in the LS-1 design which is just 3 years old now. In fact, as I mentioned, the first use of roller rockers was in the 1996 LS-4 engine which, of course, was the engine at the end of the "lineage" which dated back to 1955.
Of course, the amount of friction reduced is obviously quite minimal considering the overall friction generated in an engine. Often times, though, as I'm sure you are aware, performance is gained by the sum product of a lot of little enhancements here and there. Are roller rockers worth the cost in terms of performance increase? Probably not for the average Corvetter. But, for some folks, small benefits are worth the cost. Besides, THEY LOOK TERRIFIC! Even if you're the only one that ever sees them.
Would I ever use roller rockers? YOU BET! I've been in love with Crower stainless steel roller rocker arms since I first set eyes on them many years ago. It was a case of love at first sight.In Appreciation of John HinckleyComment
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Re: Rocker Arms
RIGHT ON! Now we identify the reason to use roller rocker arms. They look neat as all hell! That's why I use them. I carried absurdity to a higher level and got the stainless SHAFT MOUNTED version. I giggle out loud every time I visualize what they look like under the valve covers. Too damn bad everyone can't see them although I've been known to remove a cover on occasion when coaxed with a few longnecks. I've used Crower stuff for twenty years and always his rods. Dave Crower and I have spoken many times on the phone and he once made a set of lightweight rods for me that were a compromise between 5.875 and 6.000 inches long. These rods allowed an optimal ring pack and helped to achieve peak torque at a specified rpm in a racing engine.
Harlan Sharpe roller rockers look really cool when jumping up and down on a cylinder head. Gives you goose bumps. By the way, be careful adjusting the lash because if you get them too tight or you get your engine too hot they crack neatly in two sending a bunch of little roller bearings into your oiling system. J-B weld and some magnets will help in this eventuality.
Varooom!Comment
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Re: Rocker Arms
What would the cold adjustment be for an L78?Comment
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