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post #15 of (permalink) Old Feb 25th, 20, 6:04 AM
BillyGman
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Join Date: Oct 2005
Location: CT,USA
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Re: Stamped rockers BBC

Quote:
Originally Posted by mrpaticular View Post
.....But sometimes at the track the announcer will ask if anyone has an available roller. I'll stick with solid flat tappets.
Yeah, some racers at the drag strip will be running big solid roller cams with incredible pressures from triple valve springs in the 700-900 LB range. So that's gonna be tough on parts over the long haul.

Sometimes I wonder if certain parts become "the sacrificial lamb" in a certain sense. Example: if you're running a huge solid roller cam with a ton of valve lift, ( ie. .800+") you need to use real heavy/stiff valve springs as well as tough thick-wall pushrods which won't flex, and that can place lots of pressure and stress on the rocker arms. But if you lighten up on the valve springs and use more pliable/flexible pushrods that will give a little bit to soften the blow placed on the rocker arms, then you'll end up destroying the camshaft lobes and/or the valves and their seats due to valve bounce, and valve float. So perhaps the rocker arms have to take the hit and become the sacrifice in order to preserve other more expensive and more labor intensive type parts.

If you're drag racing your car, what would you rather have fail? A few rocker arms, or a camshaft and/or a valve along with it's seat? Of course some roller rocker arms can be more expensive than camshafts, a valve, and valve seat, sure. But it's a whole lot easier to replace rocker arms than a valve seat, or even a camshaft. In a perfect world ALL the valve train parts wolud be up to snuff and long-lived. But drag racing is never a perfect world. Almost always there are trade-offs. But I digress.

Going back to the comments about roller rocker arms on street cars, I'd much rather have rollers than stamped steel. Lotsa increased friction with stamped steel rockers. If you're running in a rules-limited race class which doesn't permit rollers,that's different. Or if you have a street car with a camshaft exhibiting less than .500" lift at the valve or less than 400HP at the flywheel, then it isn't like you need roller rocker arms. But if you're playing with a 500+HP build, and .550"+ lifts at the valve, I think it's a no-brainer to use roller rocker arms. After all, back in the 60's and 70's when our beloved Chevelles, (and Camaros and Novas) were coming off the assembly line, very few cars came with 500+ hp and/or valve lift more than .550" from the factory, and even the rare ones that did were mostly the special order cars requiring some type of special order code which the car salesman didn't even know about, (deleted radios, no heaters and the like). So factory cars got by with stamped steel rocker arms back then. JMO.

70 Chevelle SS clone (632 CI powered).
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