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Discussion Starter #1

check your clearances by rfesu, on Flickr

pick the right retainer/lock combo, but damn, check ALL your clerances, then run it hard and check them again

i never see anyone mention checking alignment tab distance in any valvetrain guides

comp cams specifies 0.030" (i.e. a paperclip) between rocker self aligning tabs and valve locks/retainers, i'd aim a bit higher, as roller tips can increase in compliance due to wear
 

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I have seen a few posts on this matter. The most common , using the 787-16 Comp retainer with the 648 lock and self aligning rollers. Looks like what you have. The set up doesn't leave enough valve tip height to run a s/a rocker.
 

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Discussion Starter #3
man if you think those look like 787 and 648s.. i gotta wonder. those are 10 degree locks with cutaway for lash caps, they arent even close to 648 and 787s

comp doesn't even make a 10 degree lock to fit the top of a 915 spring, so who knows what the hell they were

here's a 787 and 648 combo so you can tell the difference..


2013-04-15 14.12.47.jpg by rfesu, on Flickr

787 retainers and 648 locks are what i'm running now.. which is what comp reccommends for an aluminum headed LT1 with 915 or 918 springs with SA rockers. if you have evidence that they're no good for SA rockers, someone should call comp and let them know, because if you call them and ask, that's what they sell you..
 

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I tried to post roller rocker noise was due to clearance issues but the entire world snapped at me - well at least 17 forum members. Everyone seems to be in denial over rocker arm noise. Some how roller bearings are supposed to make more noise than a ball pivot arm.
Also the there needs to be enough clearance for the stud in the rocker too - using high lift cams. Yes the retainer to rocker and the rocker to stud need something like 0.030" or 0.060". Crane mentions this too.

Steve are those your retainers? Which rocker are u running now? Comp cast SS pivot ball or those blue roller rockers? What do u thing of the Comp SS pivot ball rockers? Do they get the job done or fail at high RPM?

Looking for my replacement rockers.
cardo
 

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Discussion Starter #5
well cardo, since you're in my thread now, i'll give you an education about bearings in this kind of environment.

i work with different types of bearings under different forces and lubrication systems in different machines, quite a bit, and i can tell you, these particular roller bearings are subjected to certain types of forces, and they are in a certain type of lubrication environment, therefore they must be designed with a certain level of compliance (hence..noise) to keep them alive.

you COULD use really tight roller bearings that weren't noisy in a rocker, they do exist. but they would fail early, because they have no forced supply of lubrication, so they would tend to force what little oil they have out. also they would have increased friction, generate excess heat, and your valvetrain geometry would have to be so perfect, since there'd be no play...

ever wondered why if you listen to a 2-stroke engine's crankcase it sounds like it's falling apart inside? it's because they have to run roller bearings on the wrist pin and crank, because a 2-stroke engine has no forced oiling system or oil sump available, it just gets a mist of oil.

a roller rocker is VERY similar to a 2-stroke rotating assembly in terms of bearing configuration, as they are a bearing surface that is "splash oiled".

to summarize:

low friction roller bearings rattle. higher friction roller bearings tend not to rattle, but require forced lubrication, or are for use in lower stress systems with shorter operational duty cycles..

every roller rocker rocker setup i've heard is way noisier than stamped ball thingie rockers. higher performance rockers also raise the level of noise consideribly due to their lower weight. heavy things in a valvetrain are quieter. if you added some weight to your roller rockers, it would quiet them down, as it would dampen the resonance of the bearings substantially.. of course that would cost performance, and at that point, you might as well run regular 'ol rockers.

im running those blue junk PRW rollers now. they work fine, im happy with them. due to all the reasons listed above, they make noise despite all clearances being verified...

i dont expect them to last forever, but they're pretty good quality for the price i gotta say.. i'll probably run them for 20-30k until i save up for something really nice. maybe shaft mounted..

those other rockers in the pic aren't comp. they're knockoffs. there's nothing wrong with pivot ball rollers, except they dont respond well to high spring pressures, all the extra pressure on the fulcrum just makes the friction even worse, and you're going to be a few ponies behind having full roller rockers. but hell even roller tip rockers are noisy..
 

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"well cardo, since you're in my thread now, i'll give you an education about bearings in this kind of environment." Reads like your butt is still hurt over roller bearing noise from a post months ago. And it shows the truth does hurt.

So y the what did u post "check your clearances" and post pix of a vlv train self destruction for?:screwy: Did that vlv train go silently or at least quietly?:lol: Sorry, an engineer u ain't and your reply full of opinions and assumptions won't get u a cup of java at Starbucks.

Don't worry 'bout my participation in "your post(s)" anymore as u have made my ignore list. I can only hope u return the favor.
cardo
 
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