Are 1.8 rockers too much with this cam?
12-29-2005, 01:11 PM
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Are 1.8 rockers too much with this cam? stock bore, LS1 cam is 224/230 .569/.578
I am thinking of changing rockers. HS 1.8's are only $5 morethan 1.7's
Lift would be .603/.612. How would duration be affected?
This is for a FI application
I am thinking of changing rockers. HS 1.8's are only $5 morethan 1.7's
Lift would be .603/.612. How would duration be affected?
This is for a FI application
12-29-2005, 01:38 PM
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Originally Posted by WS6FirebirdTA00
why do you want to change rockers? are your stock ones broke?
i woudl check p-v clearance and make sure you have enough if u go larger ratio. it also wont do anything to the duration
i woudl check p-v clearance and make sure you have enough if u go larger ratio. it also wont do anything to the duration
I've read about valve float, but not sure that HS rockers are the culprit.
12-29-2005, 02:48 PM
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Not questioning the stock rockers, but are the HS non-adj's any good, or can they contribute to problems?
And would going to 1.8's show much difference?
And would going to 1.8's show much difference?
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12-29-2005, 10:21 PM
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Originally Posted by MAC4264
I would not do it. ( If you don't believe me check my other posts) If the stock ones are not broke don' t fix them. Spend the money on something else.
12-30-2005, 06:49 AM
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I can't answer your question on whether the lift is appropriate for you application since I'm not an FI guy (although my assumption is that you don't really need the extra lift since you can adjust your FI components to get the HP that you want).
As far as 1.8 vs. 1.7, I chose 1.8 because I'm decided to decrease the lift of the cam and place it on the rocker side. This was in the hope that it would cause less VT wear and deflection on the lifters (see my sig for lifts). However, you do limit yourself to the number of cams you can choose from. Basically, with my setup, Crane/Vinci is the only ones who grind their cams to take advantage of this.
What I will tell you is that I love the ADJUSTABLE rockers way more than the NON-ADJUSTABLE. It gives me the opportunity to adjust my VT geometry (via the swipe method) and set preloads easily, without shims.
Therefore, if I were you, and had the money, go with the 1.7 adjustables. You will have plenty of cam options and will easily be able to adjust your valvetrain.
As far as 1.8 vs. 1.7, I chose 1.8 because I'm decided to decrease the lift of the cam and place it on the rocker side. This was in the hope that it would cause less VT wear and deflection on the lifters (see my sig for lifts). However, you do limit yourself to the number of cams you can choose from. Basically, with my setup, Crane/Vinci is the only ones who grind their cams to take advantage of this.
What I will tell you is that I love the ADJUSTABLE rockers way more than the NON-ADJUSTABLE. It gives me the opportunity to adjust my VT geometry (via the swipe method) and set preloads easily, without shims.
Therefore, if I were you, and had the money, go with the 1.7 adjustables. You will have plenty of cam options and will easily be able to adjust your valvetrain.
12-30-2005, 07:18 AM
#12
Some aftermarket rockers have higher rotary moments of inertia (weight doesn't matter, believe it or not)
A 1.8 rocker will feed more spring load back into the lifter and pushrod, so the lifter and pushrod must be able to take this load. I have done much research on this subject, and have found that 625 lbs. is about the maximum you can run for lifter open load (open spring pressure X rocker ratio). So obviously, you can run a higher spring force on the 1.7's than you can on the 1.8's. A good stiff pushrod is also necessary
The 1.8 rockers will get you some additional power
The key is to make your inertial masses as low as you can, and those accelerating faster are more critical so the spring and valve mass are key.
A lot of people just blow off any rockers but stock as causing problems, they don't cause problems but do require more investigation into the valve train to make them work in the RPM range you want. There are a lot of guys running Crane rockers to very high RPM's. Tony Mamo runs the Crane 1.7's on his car, so that you tell you something.
A 1.8 rocker will feed more spring load back into the lifter and pushrod, so the lifter and pushrod must be able to take this load. I have done much research on this subject, and have found that 625 lbs. is about the maximum you can run for lifter open load (open spring pressure X rocker ratio). So obviously, you can run a higher spring force on the 1.7's than you can on the 1.8's. A good stiff pushrod is also necessary
The 1.8 rockers will get you some additional power
The key is to make your inertial masses as low as you can, and those accelerating faster are more critical so the spring and valve mass are key.
A lot of people just blow off any rockers but stock as causing problems, they don't cause problems but do require more investigation into the valve train to make them work in the RPM range you want. There are a lot of guys running Crane rockers to very high RPM's. Tony Mamo runs the Crane 1.7's on his car, so that you tell you something.
