Re: Camshaft Help WARNING LONG
[Re: titan]
#1248309
06/10/12 11:40 AM
06/10/12 11:40 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Hello. I Am Doing A Rustoleum Rebuild On A '72 400 with 55,000 miles on it. It Will Be A Temporary Engine Until I Build My Stroker In The Future.I Do However Plan On Stepping It Up A bit By Adding A Fresh Set Of Big Valve Mildly Ported Closed Chamber Heads I Have, A R.P.M. Intake With 750 Holley & A Cam. The Cam I Do Not Already Have, But Was Looking At The Whiplash Grind From Hughs & Have Some Questions.On A Desk Top Dyno It Appears To Make Pretty Good Power With A Fairly Choppy Idle.I Do Not Really Care About The Choppy Idle As Much As The Power Output. So, What Aspect Of The Whiplash Cam Accounts For The Choppy Idle Quality? Can I Lower That And Retain Or Better Yet Achieve even more Power?Here Are The Whiplash Specs.
Lift .518 @ 1.5 Rocker Arm
DUR @ .050 229/242
LS 107 deg
IO 12.5 BTC
EO 53 BBC
IC 36.5 ABC
EC 9 ATC
LSA... if you go with a wider LSA it will smooth out...
it closes the intake later which gives you less cyl
pressure in low rpm
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Re: Camshaft Help WARNING LONG
[Re: MR_P_BODY]
#1248310
06/10/12 11:55 AM
06/10/12 11:55 AM
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Joined: Feb 2004
Posts: 6,257
acworth / N. georgia - south e...
cheapstreetdustr
master
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master
Joined: Feb 2004
Posts: 6,257
acworth / N. georgia - south e...
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the 107 number on your cam.. go to 106 for a more radical sound 110 112 for a smoother idle... just for reference. as you look at cams.. we are not talking/adressing performance in this answer...only idle quality.. Imho if its a street car..look for lower mid range power/increases and anything that increases cyl pressure on those dished low compression pistons that 400 comes with.. (in your scenario) increasing head flow at this point isnt going to give you a gain in low rpm performance. vrs money spent. but the right cam and intake sure will.... unless your 48k converter and 4.56 and planning on revving it all the time to find power. fwiw 
365" Iron J heads,,3480lbs best 1.39 60ft on SS springs.10.54,124 mph ...6.67 1/8th et.average 60fts 1.46 w/ small cam &.063 no2 pill tagged & insured
[image][/image]
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Re: Camshaft Help WARNING LONG
[Re: titan]
#1248312
06/10/12 04:05 PM
06/10/12 04:05 PM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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Quote:
So What I Gather From What You are saying Is, To Widen Lobe Sep. I Will Loose Choppy Idle Some, But Also Loose Cylinder Pressure? I Do Not Want That, Have To Just Keep The Choppy Idle.
No he means the camshaft installed centerline. The lobe seperation angle is ground in the cam and cannot be changed.
We run a .030 over 400 (406) in my sons Dart. Its a pump gas street car that he drives to the track like me. He uses the RPM intake with a 750 DP also and it seems to work real good on it as he tried an 830 and a 800 and the 750 still ran the best. It has EDDY RPM heads that are cut a little for 10.6 comp and it runs fine on 92 pump. We use the MP .557 solid cam in it on a 105 centerline and he really likes it. It weighs just about 3600 lbs with him in the car and uses 3.91's with a Dynamic 9.5 converter. His best ever pass was 11.45 @ 117 in good air. Normally runs 11.50's to 11.70's on hotter days. But for a stock stroke 400 it works pretty good as you seem to never see anyone run a stock stroke 400 anymore as all are always stroked. I think half the people dont believe its not a stroker. Good luck with yours. Ron
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Re: Camshaft Help WARNING LONG
[Re: 383man]
#1248313
06/10/12 08:18 PM
06/10/12 08:18 PM
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Joined: Apr 2006
Posts: 4,220
West Plains, MO
DrCharles
master
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master
Joined: Apr 2006
Posts: 4,220
West Plains, MO
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Quote:
Quote:
So What I Gather From What You are saying Is, To Widen Lobe Sep. I Will Loose Choppy Idle Some, But Also Loose Cylinder Pressure? I Do Not Want That, Have To Just Keep The Choppy Idle.
No he means the camshaft installed centerline. The lobe seperation angle is ground in the cam and cannot be changed.
Well, that's definitely true, but I think the post meaning is: cams with tighter LSA's tend to have rougher idles. So to get a smoother idle he would need to change to a cam with a wider LSA... right? 
I suppose advancing the installed centerline would help the idle too, but that's not usually why cams are advanced...
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Re: Camshaft Help WARNING LONG
[Re: DrCharles]
#1248314
06/10/12 09:29 PM
06/10/12 09:29 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
Quote:
So What I Gather From What You are saying Is, To Widen Lobe Sep. I Will Loose Choppy Idle Some, But Also Loose Cylinder Pressure? I Do Not Want That, Have To Just Keep The Choppy Idle.
No he means the camshaft installed centerline. The lobe seperation angle is ground in the cam and cannot be changed.
Well, that's definitely true, but I think the post meaning is: cams with tighter LSA's tend to have rougher idles. So to get a smoother idle he would need to change to a cam with a wider LSA... right?
I suppose advancing the installed centerline would help the idle too, but that's not usually why cams are advanced...
The 107 LSA cam has more over lap than a 112 lsa
the over lap is the roughness/choppy idle and if
you advance the cam that only makes more cyl pressure
due to the valve closing sooner but the choppy idle
will still be there
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Re: Camshaft Help WARNING LONG
[Re: DrCharles]
#1248315
06/11/12 12:16 AM
06/11/12 12:16 AM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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Quote:
Quote:
Quote:
So What I Gather From What You are saying Is, To Widen Lobe Sep. I Will Loose Choppy Idle Some, But Also Loose Cylinder Pressure? I Do Not Want That, Have To Just Keep The Choppy Idle.
No he means the camshaft installed centerline. The lobe seperation angle is ground in the cam and cannot be changed.
Well, that's definitely true, but I think the post meaning is: cams with tighter LSA's tend to have rougher idles. So to get a smoother idle he would need to change to a cam with a wider LSA... right?
I suppose advancing the installed centerline would help the idle too, but that's not usually why cams are advanced...
After I read it again I believe you are right. I think he just means different cams as I thought he was saying to advance and retard the cam in it. Ron
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