Who would add 1.8RR with this cam??
06-08-2005, 02:43 AM
#1
Could I add 1.8RR with this cam?? I got a 234/230 578/578 112 cam. I want more lift. Its got stock heads and block. I want to get the Harlan Sharp 1.8 Rockers but want to know if it will be safe to do so. Whats your opinion. Thanks.
Last edited by 00tals1; 06-10-2005 at 11:00 AM.
06-09-2005, 01:13 AM
#3
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that would make your cam about a 245/242 with 0.612 lift. Pretty borderline on the piston-valve clearance, if it even clears. With stock heads, it won't do you much good anyway. Why do you think you want more lift? .578" is more than ample on your stock heads. what you need is a more aggressive ramp to take advantange of your mid-lift flow, not your peak-lift flow.
06-09-2005, 03:32 AM
#4
The cam makes good power in my opinion. I got Jantzer TB, LS6 intake, March Pulley, Pacesetter LT's with True Duals 2 1/2 x pipe and 2 1/2 one chamber flows and its been tuned. Its makes 387 RWHP 367RWT on a dyno jet. I want to get 400RWHP. I see alot of cams with a 230-239 duration have high lift numbers like 595-599. I think I could gain some more HP with 1.75 or 1.8 Rockers and another tune since my tune was through a y pipe and not duals.
Last edited by 00tals1; 06-09-2005 at 03:45 AM.
06-09-2005, 05:21 AM
#5
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Well, added lift = more power as long as your heads are up to the task so I'm in full agreement that a set of 1.8 rockers would give you gains, but just be sure you have proper PTV clearance for them.
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06-10-2005, 08:27 AM
#8
That ramp will not go well with 1.8 rockers. Maybe try some different mufflers and retune for the dual exhaust and see what you get. It would probably be cheaper to change the cam to a conventional split with say 232°/236° and .591"/.595" or so specs.....112° LSA +4°. That might work better in the long run. Or have your heads re-worked. 
06-10-2005, 11:02 AM
#10
Ramp or Ramp Rate means the acceleration profile of the lobe. If you have a given lift of .578", then a lobe with 234° has a somewhat steep ramp. The same lift on a 236° lobe has a more gradual ramp. But the same lift on a 220° lobe has a very steep ramp.
Think of it as a pyramid. With a given height at the peak, the pyramid with the broader base (larger duration) will have a less steep ramp to the peak.
Going to a 1.8 rocker will increase the ramp rate of the cam lobe. This is usually not desirable unless you have .530" or less lift in your cam with the stock 1.7 rocker.
Most rocker kits are $500 or more, so I would think a new cam would be similar $$$ total, and have better valvetrain dynamics.
Just my $.02.
Think of it as a pyramid. With a given height at the peak, the pyramid with the broader base (larger duration) will have a less steep ramp to the peak.
Going to a 1.8 rocker will increase the ramp rate of the cam lobe. This is usually not desirable unless you have .530" or less lift in your cam with the stock 1.7 rocker.
Most rocker kits are $500 or more, so I would think a new cam would be similar $$$ total, and have better valvetrain dynamics.
Just my $.02.
06-10-2005, 11:12 AM
#11
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My cam, .538/.538 228/228 114, would be good for 1.8 rockers then right? Not trying to steal the thread...but what is the formula for figuring out the lift with 1.8 vs. 1.7?
06-10-2005, 11:20 AM
#12
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00tals1 - go with a 1.75:1 rocker.
byrontaylor - 1.8 rockers would give you about 0.570" lift and stretch your duration to about 240, which is a pretty big cam. Your clearance should be ok, but you may lose some power down low. you will make good power with either 1.75 or 1.8 rockers.
byrontaylor - 1.8 rockers would give you about 0.570" lift and stretch your duration to about 240, which is a pretty big cam. Your clearance should be ok, but you may lose some power down low. you will make good power with either 1.75 or 1.8 rockers.
06-10-2005, 11:24 AM
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Originally Posted by byrontaylor
...but what is the formula for figuring out the lift with 1.8 vs. 1.7?
Multiply your existing lift by 1.8 and divide by 1.7. This will give you valve lift with 1.8 rockers.
06-10-2005, 11:27 AM
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Originally Posted by gtovan
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Multiply your existing lift by 1.8 and divide by 1.7. This will give you valve lift with 1.8 rockers.
Multiply your existing lift by 1.8 and divide by 1.7. This will give you valve lift with 1.8 rockers.
Now, how about the duration? what would mine be with 1.75's...240 is a little high for me I think.
06-10-2005, 11:33 AM
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Another question, what would like 7.450 pushrods do to his cam? Would that be a cheaper option? Seems like it would just .050 lift to the cam but I'm sure it isn't that simple.
06-10-2005, 12:03 PM
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Originally Posted by byrontaylor
Now, how about the duration? what would mine be with 1.75's...240 is a little high for me I think.
Going to 1.8's from 1.7's doesn't change your duration at the absolute opening point or absolute closing point of the valve, the .00 lift number. What it will change is the point that your valve reaches the .050 lift number through opening the valve quicker and delaying closing which is commonly quoted as the cam duration (228/232 ect.) due to the multiplication of 1.8 vs. 1.7. By going to 1.8 you effectively increase the aggressiveness of the lobe profile, the valve action is magnified.
06-10-2005, 12:27 PM
#18
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Originally Posted by gtovan
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Going to 1.8's from 1.7's doesn't change your duration at the absolute opening point or absolute closing point of the valve, the .00 lift number. What it will change is the point that your valve reaches the .050 lift number through opening the valve quicker and delaying closing which is commonly quoted as the cam duration (228/232 ect.) due to the multiplication of 1.8 vs. 1.7. By going to 1.8 you effectively increase the aggressiveness of the lobe profile, the valve action is magnified.
Going to 1.8's from 1.7's doesn't change your duration at the absolute opening point or absolute closing point of the valve, the .00 lift number. What it will change is the point that your valve reaches the .050 lift number through opening the valve quicker and delaying closing which is commonly quoted as the cam duration (228/232 ect.) due to the multiplication of 1.8 vs. 1.7. By going to 1.8 you effectively increase the aggressiveness of the lobe profile, the valve action is magnified.