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Old 04-28-2020, 02:05 PM
Steve C. Steve C. is offline
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Personally I would check valve springs at their actual verified installed height and with their intended retainers in place, both new and used. I've had my engine builder check brand new springs out of the box and have found them to be way off. Measured on the high side, so much they were unusable for the intended application.

Comp Cams suggests after the spring has been “broken-in”, it is common for it to lose a slight amount of pressure. Once this initial pressure loss occurs, the spring pressure should remain constant unless the engine is abused and the spring becomes overstressed.

Related, on one build years ago I asked my engine builder to remove a few springs after the dyno session. We found one had lost 11 pounds pressure and another lost 14 lbs !

Valve springs are probably the most stressed components of an engine.
Yet they are also one of the most oft-overlooked parts in the entire engine.


.

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  #22  
Old 04-28-2020, 07:58 PM
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I’ve personally run that voodoo 704 cam in my previous 400ci combination with a 4-speed and 3.36 rear gears. I installed the cam straight up and there was no disappointment anywhere from 1500-5800. My car pulled very hard and I wouldn’t hesitate for a second to run that cam again in a future build.

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  #23  
Old 04-30-2020, 07:05 AM
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The RAIV cam never disappoints in a pump gas 455 build and you can run at or a bit over 10 to 1 compression on pump gas w/o issues. The long seat timing, wide LSA and 87 degrees overlap become your friend at that point.

Topped with high ratio rocker arms and Rhoads lifters it will mimic the power from a very well chosen hydraulic roller cam at much less cost.

That's not regurgitated BS or Googling up someone else's test results from a very generous dyno. We actually did some back to back cam testing with my last 455 engine. We didn't set our to test camshafts, my engine was simply out to be "freshened up" as it really started to loose power and the car was slowing down at the track. That simply turned out to be a stretched all to chit Rollmaster timing chain(yes, that's not a typo, but I had a LOT of time on that timing set by then with many hundreds of track runs and thousands of street miles) so would have been a much easier fix but since the engine was out I wanted to install a "modern" cam to make more power.

I also wanted to go with a flat solid cam to take the hydraulic lifter action out of the equation. We had Comp grind a 240/248 @ .050" cam for us on a 112LSA. It not only had 10 degrees more duration than the Crower RAIV clone it also had a lot more lift. Everyone involved thought it would be a good replacement for the RAIV cam making more power and still idling pretty decent.

The ONLY part that ended up being true was the idling pretty decent part. It idled better making over 2" more vacuum at idle than the RAIV cam with Rhoads lifters on it. I knew we were in trouble before making the first pull on it and I was correct. The engine LOST 10hp/22ft lbs torque and quit just past 5000rpms instead of peak power at 5600rpm's. Bummer. Tried just about everything and the only improvement was found by "tight lashing" the big solid cam and even then the numbers only jumped slightly. This clearly showed us that we chose the big flat solid too small, another lesson learned with these things. We could have EASILY went another 8-10 degrees @ .050" and most likely would have got to where we wanted to be and the engine would have behaved well at idle and down in the normal driving range as well....IMHO

Anyhow, out it comes and in goes a custom ground HR cam with XFI .361" lobes, 230/242 @ .050" and over .600" lift with the high ratio rockers. It only had 284/296 seat timing so I thought for sure it would outrun the old/antiquated RAIV cam everyplace. Well, that didn't go as planned either.

It did make more power but barely and it took several pulls and a little tuning to see it. Even after pulling out all the stops we only saw 3hp/4ft lbs improvement and it was done at 5400rpm's instead of 5600. Hum, over $1000 on a "modern" roller cam set-up to only see a few HP and ft lbs torque and pulled peak power down some.

Anyhow, the engine goes back in the car and I went back to racing it couple of times a week. At the track the car was now close to a tenth quicker and 1-2 MPH faster. I averaged hundreds of runs and did pick up some. Best ET obtained with the RAIV cam was 11.64 at 114mph, the HR cam managed a best of 11.52 @ 116. So the $1000 investment was worth something. However, depending on your point of view, we ran very well with the "old" flat cam/Rhoads lifters/high ratio rockers for considerably less money spent.

So it really does work as advertised.....you can choose a pretty hefty flat cam, tame it some with Rhoads lifters to improve idle and power in the "normal" driving range, top it with high ratio rockers arms, and make great power with one of these engines..........Cliff

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Last edited by Cliff R; 04-30-2020 at 07:11 AM.
  #24  
Old 04-30-2020, 07:41 AM
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Quote:
Originally Posted by gtofreek View Post
Either cam will run fine, but my preference, of course, would be the Voodoo. I think it will be more explosive when you step on the throttle. Never been disappointed with the 704 Voodoo in a 455. Install it on a 104-106° ICL.
X2!!!!! The only thing I will say is it does NOT like to go slow.. The 5 speed I have in the car has a 3.27 first gear, and at the time I needed that. Now I have 3.5 rear gears and way more HP. First is kinda useless. I plan on changing to a different transmission in the future to cure that.

But the cam is a great choice. Its sweet spot for me is the 60-100 mph range. Wicked fun.

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  #25  
Old 04-30-2020, 01:10 PM
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Anyone install Rhoads lifters with 1.65 rockers on their engine BEFORE Jim Hand? I recall Jim did it in the 90's

  #26  
Old 04-30-2020, 02:13 PM
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Does anyone have Cam Dr files for the any version of 041 and / or the Lunati 704?

These numbers are based on simulated / generated lobe lift files and calculate valve lift using a constant rocker arm ratio.

Stan

Simulated 041 w 1.65:1
VALVE_____Lift______Opens___Closes__Duration
_________________Deg_BTDC__Deg_ABDC_____________Ar ea
_________0.00600____30.16_|__96.87_|_307.04_|__42. 08
_________0.05000_____9.56_|__60.06_|_249.62_|__41. 45
_________0.10000____-2.83_|__45.82_|_222.99_|__40.47
_________0.20000___-20.97_|__26.81_|_185.85_|__37.73
_________0.30000___-38.32_|___8.83_|_150.51_|__33.21
_________0.40000___-58.94_|_-11.96_|_109.10_|__26.18
_________0.45000___-72.54_|_-25.45_|__82.01_|__20.22
_________0.50000___-93.99_|_-46.78_|__39.23_|__10.19

Simulated Lunati 704 w 1.5:1
VALVE_____Lift______Opens___Closes__Duration
_________________Deg_BTDC__Deg_ABDC_____________Ar ea
_________0.00600____29.95_|__69.95_|_279.90_|__40. 45
_________0.05000____12.85_|__52.85_|_245.70_|__40. 01
_________0.10000_____0.91_|__40.91_|_221.82_|__39. 10
_________0.20000___-18.40_|__21.60_|_183.20_|__36.25
_________0.30000___-37.00_|___3.00_|_146.00_|__31.76
_________0.40000___-59.22_|_-19.22_|_101.56_|__23.67
_________0.45000___-74.01_|_-34.01_|__71.98_|__17.26
_________0.50000__-100.49_|_-60.49_|__19.02_|___4.78

Simulated Lunati 704 w 1.55:1
VALVE_____Lift______Opens___Closes__Duration
_________________Deg_BTDC__Deg_ABDC_____________Ar ea
_________0.00600____30.09_|__70.09_|_280.18_|__41. 80
_________0.05000____13.30_|__53.30_|_246.60_|__41. 39
_________0.10000_____1.60_|__41.60_|_223.21_|__40. 51
_________0.20000___-17.22_|__22.78_|_185.56_|__37.66
_________0.30000___-35.12_|___4.88_|_149.76_|__33.12
_________0.40000___-55.96_|_-15.96_|_108.09_|__26.08
_________0.45000___-69.25_|_-29.25_|__81.51_|__20.13
_________0.50000___-88.37_|_-48.37_|__43.26_|__11.05

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  #27  
Old 04-30-2020, 05:30 PM
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Quote:
Originally Posted by Stan Weiss View Post
Does anyone have Cam Dr files for the any version of 041 and / or the Lunati 704?
No files but I have some more numbers on these Voodoo 704 lobes from Harold.

VooDoo--------.100"---.200"---.300"
Intake ----------203.9--146.4---74.8
Exhaust --------211.9---154.4---88.0

  #28  
Old 04-30-2020, 05:48 PM
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Quote:
Originally Posted by pastry_chef View Post
Anyone install Rhoads lifters with 1.65 rockers on their engine BEFORE Jim Hand? I recall Jim did it in the 90's
HO Racing 🤔

  #29  
Old 04-30-2020, 06:01 PM
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Quote:
Originally Posted by pastry_chef View Post
No files but I have some more numbers on these Voodoo 704 lobes from Harold.

VooDoo--------.100"---.200"---.300"
Intake ----------203.9--146.4---74.8
Exhaust --------211.9---154.4---88.0
Mike,
Thanks. I will generate a new curve and see what that looks like. This is from my present curve.

Stan

CAM_______Lift______Opens___Closes__Duration
_________________Deg_BTDC__Deg_ABDC_____________Ar ea
_________0.00600____28.00_|__68.00_|_276.00_|__26. 96
_________0.05000_____6.50_|__46.50_|_233.01_|__26. 42
_________0.10000____-9.10_|__30.90_|_201.79_|__25.22
_________0.15000___-22.96_|__17.04_|_174.08_|__23.60
_________0.20000___-37.00_|___3.00_|_146.00_|__21.17
_________0.25000___-53.04_|_-13.04_|_113.92_|__17.34
_________0.30000___-74.01_|_-34.01_|__71.98_|__11.51

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  #30  
Old 04-30-2020, 07:20 PM
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I think the duration at 0.006 lifter rise is not accurate in those files. I think the voodoo 704 is actually 281 degrees not 276. Also iv measured a 60919 cam and it is about 286 at 0.006 so I’d guess the raiv is similar. These are the results I got from measuring a new 60919 intake lobe and the durations I believe a 704 actually are.
60919 704
.006. 286 281
.050 231 233
.200 140 146

  #31  
Old 04-30-2020, 09:24 PM
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From what I understand having read some of UD-Harold's writings. His lobes were symmetrical with a small amount / section of asymmetrical at the very end of closing. Which makes not real difference when talking about its duration. It would look something like this but not identical.

Stan
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  #32  
Old 04-30-2020, 09:45 PM
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Real meat and potatoes. I’m loving this data mining. Thanks everyone. Super cool!


Sent from my iPhone using Tapatalk

  #33  
Old 04-30-2020, 10:04 PM
Steve C. Steve C. is offline
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Some of harold brookshire cam thoughts compiled:

https://www.tapatalk.com/groups/clev...ed-t17161.html


"Every cam I design is designed the same way, unsymmetrical, with a delayed, fast-opening, and a delayed, gentler closing side."

More on the hows and whys of the unsymmetrical cam by Haold in post #31 Here:

https://forums.maxperformanceinc.com...cal+cam&page=2

.

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Last edited by Steve C.; 04-30-2020 at 10:12 PM.
  #34  
Old 05-01-2020, 07:16 AM
jamaca85 jamaca85 is offline
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what ever you decide, make sure the springs are set up for the cam you go with. if in doubt just buy the cam lifter and spring set and have a machine shop install the springs on the heads, just make sure you give him the cam info. this way you wont have any issues. with the 1.65 you will have to modify the pushrod holes on the heads too. with the 1.52 you wont. this way you have it all done right with no surprises when you run the car at WOT.....good luck

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  #35  
Old 05-01-2020, 07:23 AM
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Also note also that in terms of push rod to guide hole clearance that with a hydro lifter if you do the normal adjustment of 1/2 turn down of preload that you are changing the geometry some and also changing that guide hole clearance some too boot!

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