Re: Anyone ever go faster with less lift?
[Re: mopar dave]
#3018549
02/24/22 03:13 PM
02/24/22 03:13 PM
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Joined: Oct 2007
Posts: 4,219 New York
polyspheric
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the adjusters almost all the way out reduces the ratio slightly
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Re: Anyone ever go faster with less lift?
[Re: polyspheric]
#3018557
02/24/22 03:43 PM
02/24/22 03:43 PM
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Joined: Dec 2021
Posts: 1,404 Loudoun County, VA
Brad_Haak
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the adjusters almost all the way out reduces the ratio slightly Depends upon the brand / design of the rocker. You can't say either way without having measured the lift curve with the adjusters at max and min extensions. Yes, I have data to validate my statement.
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
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Re: Anyone ever go faster with less lift?
[Re: Brad_Haak]
#3018571
02/24/22 04:27 PM
02/24/22 04:27 PM
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polyspheric
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If the adjuster is parallel to the pushrod axis it always does, by extended the length of the pushrod lever. I have the trigonometry.
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Re: Anyone ever go faster with less lift?
[Re: mopar dave]
#3018575
02/24/22 04:29 PM
02/24/22 04:29 PM
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Posts: 4,219 New York
polyspheric
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A bigger rocker ratio is also a test of "Is my cam close to being too much for my displacement, static CR, ICL, LSA?". Less power says: could be.
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Re: Anyone ever go faster with less lift?
[Re: polyspheric]
#3018591
02/24/22 05:03 PM
02/24/22 05:03 PM
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Joined: Dec 2021
Posts: 1,404 Loudoun County, VA
Brad_Haak
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... I have the trigonometry. Since you insist on... well, just being you, I suppose: - You made a blanket statement: "the adjusters almost all the way out reduces the ratio slightly" - I responded that it depends upon the rocker, etc. I have data that shows it both ways, depending upon the rocker geometry. - You said "I have the trigonometry". - I have the CAD files that validate my baseline measurements within .002-.003". No doubt they factor in the trigonometry, as well.
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
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Re: Anyone ever go faster with less lift?
[Re: mopar dave]
#3018592
02/24/22 05:03 PM
02/24/22 05:03 PM
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Posts: 14,545 So. Burlington, Vt.
fast68plymouth
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I haven’t measured yet, but I think it’s gonna take a pushrod about .250 shorter. So, you have basically zero threads(or less) showing below the rocker now(pushrod cup almost touching rocker body). The adjuster being screwed up in to the rocker body further generally increases the ratio(slightly).
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Anyone ever go faster with less lift?
[Re: Brad_Haak]
#3018593
02/24/22 05:12 PM
02/24/22 05:12 PM
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Joined: Dec 2021
Posts: 1,404 Loudoun County, VA
Brad_Haak
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For first diagram, the "A" measurements are with the pushrod adjuster extended about .100" beyond where they should have been. The "B" test is w/ the adjuster length shortened to it's min acceptable length:
Lift --- _A_ --- _B_ .010 --- 316.5 - 315 .020 --- 305 --- 303.5 .050 --- 281 --- 279.5 .100 --- 255 --- 253.5 .150 --- 235.5 - 234 .200 --- 218.5 - 217 .250 --- 203 --- 202.5 .300 --- 189 --- 187.5 .350 --- 175 --- 173 .400 --- 159.5 - 158 .450 --- 145 --- 143 .500 --- 127.5 - 126 .550 --- 109.5 - 107.5 .600 --- 87 ---- 85 .650 --- 56 ---- 53.5
Lift -- .685" - .682"
The second diagram represents the config for the "C" (long adjuster) and "D" (short adjuster) measurements:
Lift --- _C_ --- _D_ .010 --- 314.5 - 315.5 .020 --- 303 --- 303.5 .050 --- 279 --- 279 .100 --- 253 --- 253 .150 --- 232.5 - 233.5 .200 --- 216 --- 216 .250 --- 200 --- 200.5 .300 --- 185.5 - 185.5 .350 --- 170 --- 170 .400 --- 155 --- 155.5 .450 --- 139 --- 140 .500 --- 121 --- 123 .550 --- 101 --- 103 .600 --- 76 ---- 79 .650 --- 35.5 -- 42.5
Lift -- .663" - .670"
============================================
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
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Re: Anyone ever go faster with less lift?
[Re: Brad_Haak]
#3018640
02/24/22 08:25 PM
02/24/22 08:25 PM
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Joined: Dec 2021
Posts: 1,404 Loudoun County, VA
Brad_Haak
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This is the part of Moparts I didn't miss while I was "on vacation" for almost 2 years. I've had a few with people here over the years (including at least one person on this thread), but it's not worth the oxygen now to bother. And that's coming from someone who is quick to admit I'm a "slow learner" about these things. Hmmmm... seems I forgot what I had said not that long ago. I'm going to do my best to stay outta these petty and just go on about my business.
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
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Re: Anyone ever go faster with less lift?
[Re: Brad_Haak]
#3018654
02/24/22 09:09 PM
02/24/22 09:09 PM
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Joined: Oct 2007
Posts: 4,219 New York
polyspheric
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Maybe I just don't see it, but where are the alternate pushrod positions in the rocker indicating adjuster length?
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Re: Anyone ever go faster with less lift?
[Re: mopar dave]
#3018771
02/25/22 09:51 AM
02/25/22 09:51 AM
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Posts: 4,457 Washington
madscientist
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I will have to look at this on my pc, but looks like shorter pushrod creates more lift. IMO, using pushrod length to affect lift is a bad idea. You have a limited range of correct adjuster position. IMO the adjuster (if you are using a cup adjuster) should be as far into the rocker as it can be. If you are using a ball adjuster (depending on who made the rocker) it needs to be out 9/32 minus .050 plus zero.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: Anyone ever go faster with less lift?
[Re: polyspheric]
#3018781
02/25/22 10:28 AM
02/25/22 10:28 AM
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Joined: Dec 2021
Posts: 1,404 Loudoun County, VA
Brad_Haak
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Maybe I just don't see it, but where are the alternate pushrod positions in the rocker indicating adjuster length? A = ball-type adjuster w/ 9.200" EL (effective length) pushrod B = cup-style adjuster w/ 9.575 OAL (overall length) pushrod C = ball-type adjuster; pushrod 9.425" EL D = cup-style adjuster; pushrod 9.800" OAL
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
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Re: Anyone ever go faster with less lift?
[Re: madscientist]
#3018783
02/25/22 10:31 AM
02/25/22 10:31 AM
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Joined: Dec 2021
Posts: 1,404 Loudoun County, VA
Brad_Haak
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You have a limited range of correct adjuster position ^^^ - Each style (ball vs cup) has a "sweet spot" where it's supposed to be set. Jacking around w/ their positions for the sake of tweaking the lift curve isn't a great idea... IMO.
2021 Challenger 6.4L Scat Pack 1320 100% stock: 1.680, 11.894 at 113.75 (DA 175 ft) weight reduction, wheels, tires, Hellcat air box: 1.661, 11.686 at 115.97 (DA 710 ft)
1973 Challenger 452 ci street/strip [2008] pump gas, DOT radials: 1.454, 10.523 at 126.44 (DA 514 ft)
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Re: Anyone ever go faster with less lift?
[Re: madscientist]
#3018964
02/25/22 10:03 PM
02/25/22 10:03 PM
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Joined: Jan 2007
Posts: 8,153 Mt Morris Michigan
mopar dave
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Changing pushrod length to correct clearances was not my intension. You see, the pushrods im using to check my clearances are too long because i switched to a solid roller from a flat tappet and thought i could just use my old pushrods to get my measures for now. My current pr measure 9 1/6" long. I need 9" to maybe 8 15/16", so my old ones are not too long to get my measures after all. I have 1 thread showing on adjuster under rocker with lash using 9"pr.
Last edited by mopar dave; 02/25/22 10:05 PM.
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Re: Anyone ever go faster with less lift?
[Re: mopar dave]
#3019094
02/26/22 02:01 PM
02/26/22 02:01 PM
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Joined: Oct 2007
Posts: 4,219 New York
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I found some notes I made. My original description of the adjuster as parallel to the pushrod may be true, but it's not significant.
The shape in question is a right triangle. The geo: The adjuster thread is 90 degrees to the pushrod lever, a horizontal line equal to the lever's length (the triangle height). The exposed thread is a vertical line descending from the left edge of this line, the height is the difference (the triangle base) in adjuster positions. Draw the hypotenuse. It's longer than the 1st line. In any right triangle the hypotenuse is always the longest distance. Therefore, the pushrod lever becomes longer as the thread length increases. The valve lever length is unchanged, so the rocker arm ratio goes down.
If the pushrod lever (triangle height) is 1.00" (fairly common) and the valve lever is 1.70", the ratio is 1.7:1 If the exposed thread distance (triangle base) is increased by .100", the hypotenuse length is the square root of the sum of the squares of the 2 sides (Pythagoras). 1.00^2 + .100^2 = 1.01^.5 1.01^.5 = 1.005
The new ratio is 1.70" ÷ 1.005" = 1.691:1
If the adjuster angle is different, the math will be off, how much and in which direction? Give me the angle.
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