Rocker Arm Advice
This is a discussion on Rocker Arm Advice within the Internal Engine forums, part of the LSx Technical Help Section category; I was curious if anyone has installed the upgraded trunions from Comp Cams. Are these a good upgrade or should ...
10-28-2013, 02:31 AM #1
Rocker Arm Advice
I was curious if anyone has installed the upgraded trunions from Comp Cams.
Are these a good upgrade or should I save longer and get a set of full roller rockers such as Yella Terra?
Are the stock LS3 rockers even worth upgrading the trunions in the first place?
My LS2 w/ LS3 heads build combo should push me into the 500+ hp mark and the last thing I want is something coming apart.There are some things you just can't test in a white lab coat.
10-28-2013, 11:05 AM #2
Most will tell you the stock rockers are fine however I'm more of a full roller guy and never understood why GM went through the trouble of designing a roller fulcrum and left the tip alone.
After spending alot of money on heads I prefer to have those valve guides last as long as possible so I swap over to a full roller. If you get up there is valve lift, say the .570+ range, you are really accelerating the valve guide wear with a stock rocker tip.
I've been running the Crane full rollers with screw in studs/guide plates for 70k miles now with no issues on my wifes LS1. Makes the valvetrain completely adjustable which I also prefer.
Just another option that might save you a few bucks over Yella Terra
10-28-2013, 04:32 PM #3
Firebirdjones, thanks for the info. The cam I will be running has .584 lift and that is why I was looking for some guidance. There seems to be less out there for the LS3 and LS7 heads because of the offset intake valve, that is why I threw Yella Terra out there. I know Scorpion makes a set but not to sure about Crane or Harland. I also read that rockers that were not anodized were a bit stronger; any truth there?
10-30-2013, 05:02 AM #4
I didn't catch you were using heads with the offset valvetrain. That might limit your choices.
As far as anodizing, I figure you're talking about aluminum rockers. I haven't heard the anodizing theory myself but then again, I generally prefer to run chrome molly rockers, especially if the engine is using a fairly stout spring pressure. I do however have aluminum rockers on a couple of engines and they have been there for 15 years, all anodized, and I have no complaints. One engine has near stock spring pressure, and my wifes LS1 that is running the crane setup runs a double spring (not the behive) and has slightly more seat pressure than stock. Both are holding up fine.
For some of my other engines here, a 454 for instance with 200 lbs. seat pressure springs, I run Crower chrome molly rockers, they have been on that car for 16-17 years. On a customer engine I just built, a mild 327 with stockish 120 lbs seat pressure, I went with Comp Cams chrome molly just because it's a customer engine and I like a little added strength so there is less chance of issue down the road. So I switch around depending on the situation.
Another reason I prefer the aftermarket rockers over stock setups is that they are manufactured with closer tolerances and more accurate rocker ratios if you buy good quality. On old school stuff with those stamped steel rockers the ratios were all over the place, they are horrible. I would like to think that the LS engines have improved on rocker ratio accuracy? I haven't checked.
10-30-2013, 04:20 PM #5
Thank you very much for all this great info. You have got me re-thinking about some of my part choices and with the longevity you get out of your parts I need to look at some steel rockers.
10-30-2013, 05:07 PM #6
If given a choice I'll choose the chrome molly, but there is nothing wrong with aluminum. If you are running near stock spring pressures I wouldn't worry about it. It's the stiff spring pressures that put alot of stress on the fulcrum, so in that case I prefer something that wears a little harder. Also aluminum will flex in extreme conditions (high rpm, heat, stiff springs) After a while that flex makes them brittle and they can break (I've only seen that in race engines though after dozens of passes) Never had one fail in a street motor, but that doesn't mean it won't.
My father is currently building a 571 cubed pump gas pontiac street motor and this very subject just came up with Bischoff.
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