How much cam advance is too much?
#931129
02/17/11 02:38 PM
02/17/11 02:38 PM
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Joined: Jul 2006
Posts: 383
Essex, Ont., Canada
Fishmarket
OP
enthusiast
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OP
enthusiast
Joined: Jul 2006
Posts: 383
Essex, Ont., Canada
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I have a 418 sb with ported eddys, RPM Air Gap, Bigs 950, 10.5 to 1 etc etc. The cam is a comp custom; XFI Lobes, 242/248 on a 108 LSA. I want to get the dynamic compression close to 8.2 and have the cam installed 7 degrees advanced (engine has not been run yet). Is this too much? I hoping that the cam is small enough that it won't be a problem. The engine is going in my mostly street, 4 speed cuda with manual brakes. 
1972 Plymouth Cuda 340 4 speed
1971 Plymouth Road Runner 383 Auto
1970 Plymouth Duster /6 Auto
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Re: How much cam advance is too much?
[Re: MR_P_BODY]
#931131
02/17/11 03:06 PM
02/17/11 03:06 PM
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Joined: Aug 2008
Posts: 941
Texas, USA
ChrgrCuda
super stock
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super stock
Joined: Aug 2008
Posts: 941
Texas, USA
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Great question. My cam(254 int. 259 exh @ .050, .644 and .649 respectively) was ground on a 112 LSA and said to install to 110 degrees. I came up with 111, but was told I could increase my low end if I advanced it 2 degrees. I didn't because it's a 505 stroker BB, and it should need too much low end. Hope my reasoning wasn't too far off.
68 Cuda Notchback [Email]10.86@120[/Email]
69 Charger R/T 440/505
2009 Challenger SRT8
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Re: How much cam advance is too much?
[Re: 602heavy]
#931137
02/17/11 06:31 PM
02/17/11 06:31 PM
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Joined: Oct 2003
Posts: 3,698
NE Oklahoma
Von
master
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master
Joined: Oct 2003
Posts: 3,698
NE Oklahoma
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Quote:
the other problem is reversion through intake @ low rpms , not good for a street motor.
Sorry to jump in, but if cam is in early (Mine is at 101-102, ground on a 108) can this cause problems with idle quality..maybe due to reversion?
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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Re: How much cam advance is too much?
[Re: 602heavy]
#931138
02/17/11 09:30 PM
02/17/11 09:30 PM
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Joined: Jul 2006
Posts: 383
Essex, Ont., Canada
Fishmarket
OP
enthusiast
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OP
enthusiast
Joined: Jul 2006
Posts: 383
Essex, Ont., Canada
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Quote:
Tis a double edged sword when advancing intake centreline , obviously what this does is advance all valve events , too much advance can have the exhaust valve open too soon , especialy bad when running low compression engines with slow flame travel , sometimes the split pattern grinds just make matters worse , the other problem is reversion through intake @ low rpms , not good for a street motor.
That's what I'm asking about... my cam is in 7 degrees advanced. Would changing it to 5 degrees make that much of a difference? Doesn't comp grind most of their newer shelf grinds with 4 degrees built in? Wouldn't the "downsides" be exacerbated on a cam with 25 degrees more duration? 
Assuming piston to valve clearance is not an issue.
Thanks for your responses.
1972 Plymouth Cuda 340 4 speed
1971 Plymouth Road Runner 383 Auto
1970 Plymouth Duster /6 Auto
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Re: How much cam advance is too much?
[Re: MR_P_BODY]
#931140
02/17/11 10:04 PM
02/17/11 10:04 PM
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Joined: Jul 2006
Posts: 383
Essex, Ont., Canada
Fishmarket
OP
enthusiast
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OP
enthusiast
Joined: Jul 2006
Posts: 383
Essex, Ont., Canada
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Not sure of the weight yet, mostly street car, 4.10 rear, 275 60 15 tires.
1972 Plymouth Cuda 340 4 speed
1971 Plymouth Road Runner 383 Auto
1970 Plymouth Duster /6 Auto
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Re: How much cam advance is too much?
[Re: Fishmarket]
#931141
02/17/11 10:06 PM
02/17/11 10:06 PM
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Joined: Dec 2008
Posts: 1,200
UK
602heavy
pro stock
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pro stock
Joined: Dec 2008
Posts: 1,200
UK
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Quote:
Wouldn't the "downsides" be exacerbated on a cam with 25 degrees more duration?
& that's a good question...................you cam the motor for the application , a 440 street motor would be a dog down low when increasing duration 25 degrees , some guys like the sound of a lopey idle in their stock motors , take two stock 440s , both have the same duration #s @ .050 & both ground on a 110 lsa , only difference being duration #s @ .004"/.020" , the guy with more 'lope' will usually be leaving power on the table , overlap is a bad thing @ low rpm (street motors).
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Re: How much cam advance is too much?
[Re: Fishmarket]
#931142
02/17/11 10:17 PM
02/17/11 10:17 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:
Not sure of the weight yet, mostly street car, 4.10 rear, 275 60 15 tires.
A 72 cuda weighs a fair bit but that being said I
think I would put it in at 104 and try it... you
are running a stick and a decent gear so you should
be fine coming off the lights to impress plenty
of the people..... JMO
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Re: How much cam advance is too much?
[Re: Fishmarket]
#931143
02/17/11 10:30 PM
02/17/11 10:30 PM
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Joined: Nov 2003
Posts: 6,293
Rock Springs
Bob_Coomer
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master
Joined: Nov 2003
Posts: 6,293
Rock Springs
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Seems the older style flat tappets respond better advanced. I have run them as much as 102-103 ICL. Mostly the older MP cams anyways.
Im with the others. If the cam is advanced that much, its probably the wrong cam. Although I will say the old MP 590 runs well in at 102-103 ICL.
Most of the modern grinds I have run (flat tappets) maybe 3-4 in the past 5 years were custom pieces, they didnt need to be advanced as far, but the also had wider lobe centers than the older stuff. 106-108 ICL is typical. I can't see a custom cam needing advanced like the older stuff. Unless the cam builder just missed the profile.
I have never run a solid roller more than 107 ICL..Usually 108-109 is typical.
I had a few old Crane Pro stock Hemi cams I wanted to play with.. these cams have narrow LSA 104 was typical, I wanted to play with the cam's ICL, but found out I was out of room in valve margins. These designs are better suited for Stage V heads and Indy hemi heads that have the rotated exh valve...
But Ideally these old grinds are a good conversation piece....
A custom cam give a much better power range, just a over better cam.
I also have the small MCcandless Comp grind in a car (450cid Duster engine with)275 .575 and the old .650 comp grinds and these along with the MP 590 are about the only exceptions to the super advanced cams...103 or more is common.
I dont know how in the world these cams run like they do. I showed those specs to my machinist and he just laughed. I dont know why they run, but they perform very well for old grinds.
Last edited by Bob_Coomer; 02/17/11 10:33 PM.
[color:"red"]65 Hemi Belvedere coming soon [/color]
[color:"#00FF00"]557" Indy engine 1.07 60ft 144mph in the 8th 2100 lbs package [/color]
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Re: How much cam advance is too much?
[Re: Fishmarket]
#931144
02/17/11 10:53 PM
02/17/11 10:53 PM
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Joined: Jan 2003
Posts: 6,591
Canton, Ohio
Sport440
master
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master
Joined: Jan 2003
Posts: 6,591
Canton, Ohio
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With that size cam your fine! Your "lift events" are well within the norm of "lift windows" on both the intake and exhaust. Whats the Norm you say  In general as long as your advanced cams "lift events" falls within a 20* range, with the Window of cams, selected between 230* @ .050 and 270* @ .050 EDIT!EDIT EDIT!EDIT!EDIT! "Not to be confused with 20* of advance" You advanced yours 7* so your sitting at 20* BTDC and 42* ABDC on the intake. How does that compare to other cams "intake timing events. 10* BTDC, 42* ABDC 232* @.050 cam 20* BTDC, 48* ABDC 248* @.050 cam 30* BTDC, 60* ABDC 271* @.050 cam The exhaust events, yours, @ 7* advanced. 59* BBDC, 9* ATDC "yours" The other cams events. 47* BBDC, 7* ATDC 234* @ .050 cam 56* BBDC, 12* ATDC 248* @ ,050 cam 70* BBDC, 24* ATDC 275* @ .050 cam I think your good to go, the intakes shutting a little early but you still have its 242 dur.@ .050, it will still rev and pull, IMO Reread my post, as I first posted it , it was confusing. mike  
Last edited by Sport440; 02/17/11 11:50 PM.
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Re: How much cam advance is too much?
[Re: Sport440]
#931145
02/18/11 01:47 AM
02/18/11 01:47 AM
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Joined: Feb 2007
Posts: 1,025
Las Vegas, NV
dodgeboy11
super stock
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super stock
Joined: Feb 2007
Posts: 1,025
Las Vegas, NV
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It all really depends on the engine and what you want to do with it. Now for starters, throw out the mindset that advancing the cam increases bottom end and retarding it increases top end. While this tends to be true, it's not always the case(at least it's not that simple). The cam is going to produce the most power at a specific installed point. Case in point. The shop I used to work for had built a 468" pontiac big block. The cam had been installed straight up (110 ICL). When dynoed, this engine produced approximately 525-535 hp at its peak. Due to the shop installing the motor not understanding that the distributor needed to be engaged in the oil pump drive BEFORE cranking down on the distributor hold down, the drive split at the oil pump and the engine lost oil pressure. Long story short, the engine came back out and was sent back to us. This time I assembled the motor and installed the cam at 107 ICL with no other changes. Hp was up in the 560 range now and there was more bottom end power AND more top end power. My point is, the engine liked the cam being advanced those 3 degrees and while it did increase the bottom end, it also increased the top end and the peak numbers. Obviously the only way to know exactly where it needs to be is to have a dyno and be willing to move the cam around or to be much smarter with numbers than I am and/or rely on God giving you a little insight on what that particular engine wants the cam installed at. Or to answer your question simply, there's too much advance when the engine starts dropping power ... 
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