1.8 rocker arms
1.8 rocker arms Has anyone changed from the stock 1.7 ratio rocker arms to 1.8 ratio rocker arms and what brand? I see converted changes my .575 lift cam to .607 lift but im not sure if there is any power in that and do the pushrod lengths needed to be changed. The rocker roller tip just needs to be close to center on the valve stem. This is alternate to changing the stock needle bearings trunion upgrade to aftermarket rocker arms.
I had a 95 z28 lt1 one time that the previous owner had crane gold rocker arms on an otherwise completely stock lt1 engine that ran good and added .010 lift to the stock cam but a couple rocker arms did wear the roller tips grooved into the side of the aluminum rocker arms.
I had a 95 z28 lt1 one time that the previous owner had crane gold rocker arms on an otherwise completely stock lt1 engine that ran good and added .010 lift to the stock cam but a couple rocker arms did wear the roller tips grooved into the side of the aluminum rocker arms.
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Joined: Jan 2018
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From: Dade City, Fl.
Yes i run pac 1219s for .625 lift. I was looking into changing or upgrading the trunions but it seems even the bronze bushings wear out or get free play. I had a comp trunion upgrade kit from 2012 that sold for 125$ that i never got around to installing and sold it. It was too be used on my forged 347 14-18lbs 317s lunati cam 800hp turbo build 98 z28 after the stock engine had given out at the drag strip with 9lbs of boost. It blew up at 169k miles threw a wrist pin out the side of the block boosting in 4th hard. Never had a problem with the dual manley springs and stock rocker arms needle bearings to 6600rpm 6 speed i usually shifted just before and never tagged the rev limiter racing.
Ive since sold that car or had to part it out in 2014 and never got around to putting it together but was wondering what rocker arm upgrades they have as i havent been active with ls1 since 2013-2012 and seen they have bronze bushing. I just seen they have the 1.8 ratio vs the stock 1.7 when i looked it changed my .575 lift cam to .607 not sure if it makes much difference but with a good set of heads the test flow numbers and .550 .600 lift which are slightly different. Stock 853s flow around 230cfm at .600 and 243s 260cfm stock unported a pair of 853s ported flowed as much as a stock set of 243s from what i read that is with stock valves. Looking into refurbished or reman 243s on ebay but im currently tied up with 700$ in front c7 z06 wheels and tires. I shouldve did an underdrive pulley for the extra 10hp when i did the cam but was changing the corvette balancer and cam on a budget as they've been know to walk off stock ac delcos.
Ive since sold that car or had to part it out in 2014 and never got around to putting it together but was wondering what rocker arm upgrades they have as i havent been active with ls1 since 2013-2012 and seen they have bronze bushing. I just seen they have the 1.8 ratio vs the stock 1.7 when i looked it changed my .575 lift cam to .607 not sure if it makes much difference but with a good set of heads the test flow numbers and .550 .600 lift which are slightly different. Stock 853s flow around 230cfm at .600 and 243s 260cfm stock unported a pair of 853s ported flowed as much as a stock set of 243s from what i read that is with stock valves. Looking into refurbished or reman 243s on ebay but im currently tied up with 700$ in front c7 z06 wheels and tires. I shouldve did an underdrive pulley for the extra 10hp when i did the cam but was changing the corvette balancer and cam on a budget as they've been know to walk off stock ac delcos.
Based on seeing stock 1.7 vs 1.85 SLP rocker arms before & afters, I'd guess ~6 whp to 15 whp depending on cam and other mod's. That's assuming the valve springs are up to the higher ratio rockers.
So for 1.7 to 1.8 rocker arm change, probably ~5 whp to 12 whp given or take a little.
So for 1.7 to 1.8 rocker arm change, probably ~5 whp to 12 whp given or take a little.
Should be OK with the 1219 springs. Something I want to add here that only concerns a 2000 C5 Corvette. The 2000 C5 LS1 came with an OEM cam that had .500" lift, I&E. That means this is the only stock LS1 that guys can't run 1.8/1.85 rockers on with the stock valve springs. Why? Because you'll coil bind the springs!!! Sometimes little things like this get lost in the past, but if you don't know this, you could ruin an engine. Again, ONLY 2000 MY C5 Corvette LS1s had this much valve lift. Other years are usually OK with stock springs when going from 1.7 to 1.8 rockers. Just sayin'.......
Last edited by grinder11; Apr 29, 2022 at 11:27 AM.
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Joined: Jun 2013
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From: Nebraska, The Good Life
I put Comp Pro Magnum 1.8 roller tip rockers on my stock long block LS2. I upgraded the springs and pushrods accordingly. While when it was still NA the power increase was barely recognizable we did notice that the power output increased throughout the entire RPM range. I have since upgraded to a TVS2300 and the rockers are still doing fine of course. No idea what the rockers alone would have done to improve things with the blower when going from 1.7 to 1.8 since they were already there when the blower went on.
One thing about the Pro Magnums is that the trunions are huge and set up in such a way that they'd never allow roller bearings to spew all over the engine and the roller tips reduce valve train friction. They are much more durable than aluminum rockers since they are steel and they are not much heavier at the tip than stock rockers and lighter at the tip than aluminum rockers.
If I recall correctly the LS2 cam gives a .525 lift, with 1.8 rockers that goes up to .556. Those are not very radical lift numbers so the improvements possible with a bigger cam would likely be more dramatic.
One thing about the Pro Magnums is that the trunions are huge and set up in such a way that they'd never allow roller bearings to spew all over the engine and the roller tips reduce valve train friction. They are much more durable than aluminum rockers since they are steel and they are not much heavier at the tip than stock rockers and lighter at the tip than aluminum rockers.
If I recall correctly the LS2 cam gives a .525 lift, with 1.8 rockers that goes up to .556. Those are not very radical lift numbers so the improvements possible with a bigger cam would likely be more dramatic.
Last edited by Rich-L79; Apr 30, 2022 at 07:42 AM.
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I put 1.85 comp adjustable rockers on my work truck almost 20 years ago. No way in hell I would ever do that again. Almost as much hassle as a cam swap with not even close to the same gains. That being said, my Dad who currently owns it is still driving it around with over 342k miles, and the rockers have never even been readjusted.
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