Re: Rocker arms and actual lift at valve
[Re: boomerodell]
#3196123
12/08/23 06:00 PM
12/08/23 06:00 PM
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Joined: Jan 2003
Posts: 14,498 So. Burlington, Vt.
fast68plymouth
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What are you seeing for actual measured lift at the valve with zero lash?
There was recently a thread over on Speed-talk where someone was seeing a significant amount of deflection of the retainers…….which was skewing the true “at the valve” lift result.
You could probably test for this by using a fairly stiff feeler gage trapped between the rocker and the valve and measuring off that vs just measuring off the retainer.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Rocker arms and actual lift at valve
[Re: fast68plymouth]
#3196124
12/08/23 06:09 PM
12/08/23 06:09 PM
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Joined: Jan 2003
Posts: 14,498 So. Burlington, Vt.
fast68plymouth
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I measured net lift on only one set of Hughes rockers, and they were the older version that didn’t have the notch cut in the top. They were 1.6’s. With checking springs they calculated out at just under 1.6……like 1.58 or 1.59. With 600lbs spring force they were barely over 1.50…….like 1.51.
I’ve never checked the TF specific HS rockers, but I have checked a few of the “normal” BBM sets. Those checked closer to .05-.06 higher than the nominal ratio with checking springs, and still slightly higher than nominal with full spring force.
One set of 1.6’s on some Indy SR heads were 1.67 with checking springs, and still 1.63@.700 lift with 700lbs on it.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Rocker arms and actual lift at valve
[Re: boomerodell]
#3196137
12/08/23 06:51 PM
12/08/23 06:51 PM
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Joined: Jan 2003
Posts: 14,498 So. Burlington, Vt.
fast68plymouth
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If you’re seeing .580 at the valve, with the lash set to zero, then the effective ratio is only 1.38. I doubt there would be a “ton” of power left on the table leaving them in place, but I think all things considered for your combo, having the net ratio closer to a true 1.50 should be worth “something”. Whether that’s 5hp or 15hp, there’s only one way to know.
At this point, you have to decide if you’re willing to spend the money for different rockers or not. If your heads have the TF SR spring package, and you’re going to try different rockers, I’d step up to the HS 1.6’s.
If you’re looking for an option that’s friendlier on the wallet, buy 8 Hughes 1.6’s and put them on the intakes.
You can always start with what you have and change them down the road too.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Rocker arms and actual lift at valve
[Re: fast68plymouth]
#3196138
12/08/23 07:03 PM
12/08/23 07:03 PM
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Joined: Jan 2003
Posts: 14,498 So. Burlington, Vt.
fast68plymouth
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Looks like the individual Hughes rockers would cost roughly $256. If considering that option…….I’d buy one 1.6 and one 1.7, and mock them up and check for true net ratio, and how they impact pushrod clearance. Then decide on which ratio to buy.
If the 1.7’s are close to 1.6 net……and the pushrods aren’t too much of a fit problem…….I don’t see any reason not to go that way.
Btw, the old MP blue rockers were Cranes. The few sets of those I measured(1.5’s) were in that 1.55 ratio range when using checking springs.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Rocker arms and actual lift at valve
[Re: fast68plymouth]
#3196189
12/08/23 11:20 PM
12/08/23 11:20 PM
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Joined: Mar 2008
Posts: 553 Kentucky
clovis
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I went through something kinda similiar. I was using ball/cup pushrods and Crane rockers, which require quite a bit of adjuster to show in order to get oil to the pushrod. With changing pushrod length you probably are already on one of the issues if using ball/cup pushrods, the push rod kick-out from the ball adjuster will take out lift, so the longer the pushrod the better. I was losing over .030. I went to ball/ball pushrods on my current build with the cup adjuster and have eliminated most all the kickout. I also went to a the bigger pushrod 7/16-3/8 taper, to keep down any deflection, and I am only using 400lb springs. I do think the deflection happens more than some think, from just what Dwayne described in going from check springs to your real springs you do see a difference. I will say that like Dwayne and Andy the lift loss may not be as big an issue. I would check the scrub on what you have to see where that is, as I think this can lead to some gains if you are measuring .100 or more. The bad part is, the only way to fix is to raise the shaft. I found sometimes the rocker you use can help you out as some are shorter. When the rocker goes up it also goes out on the valve tip, a shorter rocker can help out. On mine going from a Harland to the Crane allowed me to just use a .250 spacer to fix my scrub. The motor tended to carry rpm better after that change. There are plenty of threads on here discussing it-mine is below. https://board.moparts.org/ubbthreads/ubbthreads.php/topics/2891437/re-valvetrain-issues.html
'75 Plymouth Duster Phase I 451 906/590/2-660 10.75/126 Phase II 451 Stage VI/590/1050 9.82/135 Phase III 383 906/Victor-Pump gas 11.30/119
"For by grace you have been saved through faith. And this is not your own doing; it is the gift of God,"
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Re: Rocker arms and actual lift at valve
[Re: clovis]
#3196216
12/09/23 09:50 AM
12/09/23 09:50 AM
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Joined: Jan 2003
Posts: 10,714 North Dakota
6PakBee
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I'm not sure this is of any help but I live with valve lifts and springs where you can use the stock stamped rockers. I mocked up enough of a block that I could measure the lift of a stock rocker keeping everything else the same. I took a whole pile (literately) of lifters and measured the true lift. The lifts were all over the map. What I ended up doing was grouping them into groups with relatively close lifts. Racer Brown used to recommend using the higher lifts on the exhausts so that's what I did.
I wrote down all the results but for the life of me I can't find it. Some day.....
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: Rocker arms and actual lift at valve
[Re: boomerodell]
#3196219
12/09/23 10:22 AM
12/09/23 10:22 AM
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Joined: Jan 2003
Posts: 9,997 Frostbitefalls MN (Rocky&Bullw...
gregsdart
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master
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Frostbitefalls MN (Rocky&Bullw...
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Literally every piece of the valvtrain flexs, stretchs, bends, something! From the hold downbolts, to the shafts, rockers flex, retainers flex, and all this can be seen in the design of very high end valvetrain components that are stronger to combat this. My Jesel setup with a gross lift of .867 lost .040 versus checking springs that checked spot on. Even the cam flexes, hence the bigger diameter core cams used on some race motors. Ater seeing that .040 loss of lift i decided to go with a lighter spring, taking about 50 lbs of seat load off the spring at rest. That showed less deflection of .030, a savings of .010 in net lift.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: Rocker arms and actual lift at valve
[Re: boomerodell]
#3196315
12/09/23 06:21 PM
12/09/23 06:21 PM
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Joined: Aug 2003
Posts: 43,176 Bend,OR USA
Cab_Burge
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Last edited by Cab_Burge; 12/09/23 06:21 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Rocker arms and actual lift at valve
[Re: Cab_Burge]
#3196423
12/10/23 10:48 AM
12/10/23 10:48 AM
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Joined: Dec 2021
Posts: 1,127 Loudoun County, VA
Brad_Haak
super stock
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super stock
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Loudoun County, VA
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On the Edelbrock Victors I run, Hughes 1.6 rockers measure close to 1.60 when using a checking spring. When measured with the 600+ lb open-load roller spring, all the deflection in the valve train drops the net ratio to 1.54-1.55.
I checked out some Hughes 1.7 at the same time, although I use their 1.6 rockers. Unloaded they were in the high 1.6s, but against the roller spring they dropped closer to 1.60, losing more ratio than the 1.6 rockers. I suspect this may be the result of Hughes changing their design to include a "trench" down the backbone of the rocker body. I have the early style without the "trench" and believe it's stronger (less flexible) under a load.
FWIW, I passed on my measurements to Hughes and suggested they still offer the early design as a "heavy duty" option, but never saw any response from them.
One last comment is that Hughes rockers have a regressive ratio curve, meaning they start out much higher than the advertised ratio early in the lift, then the ratio drops off as the lift increases. Think of it as starting out at 1.7 off the seat and ending up at 1.5 near peak lift, so it averages out to 1.6 overall. Some rockers are linear, some are progressive, and some are regressive.
All this ratio stuff also depends on the shaft location with respect to the valve tip, the relative length of the adjuster screw, the angle of the adjuster screw, the rocker body fulcrum length, etc. Fun, fun, fun...
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: Rocker arms and actual lift at valve
[Re: Brad_Haak]
#3196587
12/10/23 10:34 PM
12/10/23 10:34 PM
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Joined: Dec 2021
Posts: 1,127 Loudoun County, VA
Brad_Haak
super stock
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super stock
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Loudoun County, VA
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Found a pic showing the new style Hughes rocker on the left and the original style on the right, for anyone who isn't familiar w/ them
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: Rocker arms and actual lift at valve
[Re: boomerodell]
#3196738
12/11/23 03:55 PM
12/11/23 03:55 PM
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Joined: Dec 2021
Posts: 1,127 Loudoun County, VA
Brad_Haak
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super stock
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All the stuff that David Vizard preaches, FWIW, is that the exhaust is more duration-sensitive than lift-sensitive. If, as Dwayne was suggesting, you can bump up the intake ratio to Hughes' 1.6 or 1.7 (advertised) to get the additional intake lift you want for under $300, that could be worth checking out.
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: Rocker arms and actual lift at valve
[Re: Brad_Haak]
#3196745
12/11/23 04:33 PM
12/11/23 04:33 PM
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Joined: Jan 2003
Posts: 14,498 So. Burlington, Vt.
fast68plymouth
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FWIW, my suggestion for swapping out the 1.38 net ratio rockers for something that’s in the 1.5-1.6 net ratio range ……in this application……..has almost nothing to do with my concern about the max lift change/increase.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Rocker arms and actual lift at valve
[Re: fast68plymouth]
#3196754
12/11/23 05:14 PM
12/11/23 05:14 PM
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Joined: Dec 2021
Posts: 1,127 Loudoun County, VA
Brad_Haak
super stock
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super stock
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Hmmm...
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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