Rocker arms
09-23-2006, 02:47 PM
#1
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Rocker arms OK guys:
Harland Sharp
Vs.
Yella Terra
What's the difference? They both seem like very good pieces to me, but obviously, I like the Harlands more due to their price. I've never even heard of Yella Terra, but I know Harland has been around for a while.
They'll be sitting on top of a TSP MS3 cam package, and I'd just like the added security of knowing I won't be over stressing the stock rockers since I have the poorer quality 98-00 ones. I want to stick with 1.7, and I don't want an adjustable rocker. I'll be using the stock lifters. I know Yella says that you don't have to use guide plates or anything, but the Harlands don't mention wheter they do or not. I also like the fact that the Harlands pair up to stabilize each other. What's your guys' takes on these rockers?
Harland Sharp
Vs.
Yella Terra
What's the difference? They both seem like very good pieces to me, but obviously, I like the Harlands more due to their price. I've never even heard of Yella Terra, but I know Harland has been around for a while.
They'll be sitting on top of a TSP MS3 cam package, and I'd just like the added security of knowing I won't be over stressing the stock rockers since I have the poorer quality 98-00 ones. I want to stick with 1.7, and I don't want an adjustable rocker. I'll be using the stock lifters. I know Yella says that you don't have to use guide plates or anything, but the Harlands don't mention wheter they do or not. I also like the fact that the Harlands pair up to stabilize each other. What's your guys' takes on these rockers?
09-23-2006, 03:42 PM
#2
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i am pretty sure that they are both bolt ons. the knock on the harlands (if i am not mistaken) is there weight. i am sure Guitsboy will chime in here today and give a better explanation.
09-23-2006, 03:44 PM
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I'd also like to know. I'm having Yella Terra roller rockers installed right now. I know they're better than stock, but what kind of performance gain (if any) can I expect?
09-23-2006, 04:55 PM
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Don't expect a performance gain from the rockers unless your ratio is changed. If you are getting the stock ratio then you won't get a performance gain. If you search you will find tons of threads on these rockers. Brian of TEA used Harlands on his NOS vette engine and did extremely well. I used the Yella's, and got valve float at high rpm on a dyno, and the valves kicked the pistons. Not enough to do damage but it did leave smiley faces.
My experience should not be taken to mean the cause was the Yella's. It could have been many things that caused the float, like the TR224, springs, NOS, etc.
It seemed the general concensus was the Yella's where too heavy causing the value float. But, that is pure speculation and no real science. Both, are surely quite comparable and up to the task. Anytime you start changin things from stock you can expect things to happen - like valve float.
Oh yeah, they are both bolt ons.
My experience should not be taken to mean the cause was the Yella's. It could have been many things that caused the float, like the TR224, springs, NOS, etc.
It seemed the general concensus was the Yella's where too heavy causing the value float. But, that is pure speculation and no real science. Both, are surely quite comparable and up to the task. Anytime you start changin things from stock you can expect things to happen - like valve float.
Oh yeah, they are both bolt ons.
09-23-2006, 11:51 PM
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If you do want to change ratio's or have the added flexibility of being adjustable, then i would just send your stock rockers off and have them rebuilt with the better bearings.
09-24-2006, 12:09 AM
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Originally Posted by BOWTIE
If you do want to change ratio's or have the added flexibility of being adjustable, then i would just send your stock rockers off and have them rebuilt with the better bearings.
09-24-2006, 01:09 AM
#7
Shaft mount means no guide plates or hardened pushrods required because the shaft keeps the rocker in alignment. The OEMs are non adjustable which means when the shoulder flange on the OEM hex bolts bottoms out on the flat boss of the trunion you've run out of adjustability. Adjustable ones like the Comp Pro Mags don't work this way by design. The boss at the top of the rocker stud and the bottom face of the trunion are elyptical giving them the ability to move past each other certain to a degree. The trade off is that this shape also allow them to swivel which ain't good when it comes to rockers necessatating the use of guide plates to keep them from moving side to side. It's the guide plates in turn that require the use of the hardened pushrods because the OEMs can stand up to the constant rubbing against the guide plate slot without considerable gauling and eventual failure. Roller tips are no doubt better than the flat tip of the OEM stamped ones. There is something to be said for adjustability and shaft mount maintain their geometry better and don't need guide plates or a new set of expensive pushrods. Now if you could find a set that were shaft mounted AND adjustable you might have the best of both worlds. I don't know who makes this animal.
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09-24-2006, 03:29 AM
#8
Well a lot of info for you , but I will tell you what I know from my experiece with both. Yella tera's Heavy caused valve float on three engines and all three picked up power when changed to either a stock rocker and one picked up 30rwhp when they installed the Jessel's. The Harland sharps are a great rocker although they have a problem they kept on wearing out the sides they have steel guides but over a fairly short time 2-3 months they will give out and have to be replaced they stood behind them though and replaced them and just gave up and went back to a stock rocker. If you want a full roller rocker stick with Jessel. T&D's/Comp's a bit pricey, but how good of a mod is it if they don't perform up to your expectations and if one of the others do perform up to your expectations then great. Good luck.
09-24-2006, 07:50 AM
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Originally Posted by Inspector12
Well a lot of info for you , but I will tell you what I know from my experiece with both. Yella tera's Heavy caused valve float on three engines and all three picked up power when changed to either a stock rocker and one picked up 30rwhp when they installed the Jessel's. The Harland sharps are a great rocker although they have a problem they kept on wearing out the sides they have steel guides but over a fairly short time 2-3 months they will give out and have to be replaced they stood behind them though and replaced them and just gave up and went back to a stock rocker. If you want a full roller rocker stick with Jessel. T&D's/Comp's a bit pricey, but how good of a mod is it if they don't perform up to your expectations and if one of the others do perform up to your expectations then great. Good luck.
Last edited by WhiteStripes; 09-24-2006 at 07:59 AM.
09-27-2006, 12:51 AM
#12
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the jesels are expensive, lol at least compared to all the others. i have a FI application that i'm getting ready to go to (STS) and only at 5psi though. still got stock rockers, but upgraded pushrods and to dual valve springs.comp cams 926 kit mods in sig.
i don't want to be changing crap every 3 months. so if my car will be fine the way it is so be it. but right now i cannot spend 700+ on just roller rockers; the turbo kit is going on fall break( oct4th -oct 9th for me) and custom pipes will be made and it will get dynoed by the following month or so depending on time
i don't want to be changing crap every 3 months. so if my car will be fine the way it is so be it. but right now i cannot spend 700+ on just roller rockers; the turbo kit is going on fall break( oct4th -oct 9th for me) and custom pipes will be made and it will get dynoed by the following month or so depending on time
09-27-2006, 07:37 AM
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Originally Posted by Inspector12
Well a lot of info for you , but I will tell you what I know from my experiece with both. Yella tera's Heavy caused valve float on three engines and all three picked up power when changed to either a stock rocker and one picked up 30rwhp when they installed the Jessel's. The Harland sharps are a great rocker although they have a problem they kept on wearing out the sides they have steel guides but over a fairly short time 2-3 months they will give out and have to be replaced they stood behind them though and replaced them and just gave up and went back to a stock rocker. If you want a full roller rocker stick with Jessel. T&D's/Comp's a bit pricey, but how good of a mod is it if they don't perform up to your expectations and if one of the others do perform up to your expectations then great. Good luck.
Can you explain what exactly gave out on the Harland Sharps... I am planning to buy them. My cam has fairly descent lift at .571/.578 but duration is 220 and lsa 118.5 so I'm thinking it would be a good fit.
09-27-2006, 09:30 AM
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hell, i have the stock cam. going STS kit @only 5psi and dual valve springs, chromemoly pushrods...etc (comp cams 926 kit)
will the harland sharp rockers last me the life of the car without having to replace them?
otherwise i'm just going to get my stockers re-built
will the harland sharp rockers last me the life of the car without having to replace them?
otherwise i'm just going to get my stockers re-built
09-27-2006, 12:58 PM
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The new Crane shaft mounts are adjustable and use the Quick-Lift technology and geometry.
http://www.vincihighperformance.com/...0.HTMLPAGE.htm
http://www.vincihighperformance.com/...0.HTMLPAGE.htm