Re: Big cam big miles
[Re: T-bar]
#3023465
03/13/22 07:16 AM
03/13/22 07:16 AM
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Joined: May 2008
Posts: 5,399 Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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Good question? On my Victor MW heads, the short valve spring install height, and weak rocker shaft pedestals cast into the head were problem areas. I ended up milling off the pedestals and using max wedge type rocker shaft blocks. T&D now offers paired shaft rockers that would be a better solution. If going to custom rocker system, I would use valves with longer stems to make it easier to get more spring install height, then relocate the rockers for best geometry. If looking for 0.800"+ lift I would use a 1.7:1 intake rocker arm, and for long life, a more gentle cam lobe profile that can be controlled with a lower rate valve spring. An aggressive cam profile is going to want a high spring rate, which makes things harder on the valve train. On my current setup, I believe my exhaust profile (Comp HXL) with 1.6:1 rockers is too aggressive. I have though of using a 1.5:1 ratio rocker arm, and a slower opening exhaust lobe profile to take strain off the valve train. I like the idea of the bushed lifter bores with keyway roller lifters, but have no idea on how they would do with many miles on them? The keyed lifters should be lighter in weight (than the taller roller lifters with the cross bar) making the valve train more stable. I'm running the PAC 1326 valve springs, but only 0.726" lift. It is 275 seat pressure and 663 spring rate. They list as 805 open pressure @ 0.800"
If you have room for a 1.625" diameter spring, something like the PAC-1328 installs at 2.100" with 280 pounds, and has a spring rate of 629, and at 0.900" lift the pressure is 847 pounds, if that will work with your cam selection?
You would want good oil cooling of the springs too.
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Re: Big cam big miles
[Re: T-bar]
#3023484
03/13/22 09:31 AM
03/13/22 09:31 AM
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Joined: May 2004
Posts: 12,391 Taxes & Virus's R-US, NY
Dragula
I Live Here
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I Live Here
Joined: May 2004
Posts: 12,391
Taxes & Virus's R-US, NY
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I have been pushing street car boundaries for years with a big cam and cubes, except I am only at .750 lift in a 605 Hemi.....But even there, it has its price. New Titanium lash caps every year cause they mushroom....Really have to keep an eye on the pushrod tips and oil spray...I used to burn up pushrods all the time. ...Hot springs is another issue...You have to have enough oil on the springs to not eat them up as well....A big pan and pump are really necessary when doing this. I have eaten more valve train parts than most race shops over the years..A wedge would be way better than a Hemi for big cube street engine.Preferably a Predator head on Hemi block... Good Vid https://www.youtube.com/watch?v=PptxPDvbWsg
Last edited by Dragula; 03/13/22 09:35 AM.
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Re: Big cam big miles
[Re: T-bar]
#3023556
03/13/22 12:12 PM
03/13/22 12:12 PM
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Joined: Jan 2003
Posts: 31,041 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,041
Oregon
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Hello, who does or knows someone that can do big highway miles with .800"+ lift and big spring pressures? What's the problems that will arise? Spring failure, lifters? Big cube mopar motor. Drag week style events etc. You'll wants lot of oil up there for freeway driving. I'm not sure what those guys do but something like adjustable spray bar oilers might be the trick. Turn up the volume for street driving, turn it down for high rpm drag racing.
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Re: Big cam big miles
[Re: AndyF]
#3023583
03/13/22 01:07 PM
03/13/22 01:07 PM
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Joined: Jan 2004
Posts: 4,566 Motor City
6PKRTSE
master
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master
Joined: Jan 2004
Posts: 4,566
Motor City
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I run a .805/.815 on the street in my 528" Hemi with Barton rocker system with spray bar oilers with no issues.
1963 Belvedere 440 Max Wedge Tribute 1970 Charger R/T S.E. 440 Six Pack 1970 Challenger R/T, 528 Hemi 1970 Charger 500 S.E. 440 4 BBL 1970 Plymouth Road Runner 383 1974 Chrysler New Yorker 440 1996 2500 RAM 488 V-10 4X4 2004 3500 Dually Cummins 4x4 2012 Challenger R/T Classic.
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Re: Big cam big miles
[Re: 6PKRTSE]
#3023599
03/13/22 02:09 PM
03/13/22 02:09 PM
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Joined: Jan 2003
Posts: 14,499 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,499
So. Burlington, Vt.
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I run a .805/.815 on the street in my 528" Hemi with Barton rocker system with spray bar oilers with no issues. With??
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: Big cam big miles
[Re: fast68plymouth]
#3023606
03/13/22 02:30 PM
03/13/22 02:30 PM
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Joined: Aug 2011
Posts: 2,861 Pattison Texas
CSK
master
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master
Joined: Aug 2011
Posts: 2,861
Pattison Texas
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From what I have seen is they put small ratio rockers on to make the street trips, like 1.2 ratio, & put the big ratio rockers on to race.
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: Big cam big miles
[Re: 6PKRTSE]
#3023629
03/13/22 03:24 PM
03/13/22 03:24 PM
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Joined: May 2004
Posts: 12,391 Taxes & Virus's R-US, NY
Dragula
I Live Here
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I Live Here
Joined: May 2004
Posts: 12,391
Taxes & Virus's R-US, NY
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I run a .805/.815 on the street in my 528" Hemi with Barton rocker system with spray bar oilers with no issues. That's what I probably need to go to...Better check your lash caps though..
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