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At risk of being retarded #228558
02/18/09 11:57 AM
02/18/09 11:57 AM
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gulfport, ms, west mi
rowin4 Offline OP
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It seems that every magazine article on cam installation they seem to advance the cam 4 degree's . I've always set them straight up per manufacturers spec. What power potential would be gained by advancing the cam.



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Re: At risk of being retarded [Re: rowin4] #228559
02/18/09 12:01 PM
02/18/09 12:01 PM
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Romeo MI
MR_P_BODY Offline
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Quote:

It seems that every magazine article on cam installation they seem to advance the cam 4 degree's . I've always set them straight up per manufacturers spec. What power potential would be gained by advancing the cam.






More torque, the intake valve closes sooner and makes
more compression

Last edited by MR_P_BODY; 02/18/09 03:58 PM.
Re: At risk of being retarded [Re: MR_P_BODY] #228560
02/18/09 12:09 PM
02/18/09 12:09 PM
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New York
polyspheric Offline
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Typo?
Intake valve closes sooner.


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Re: At risk of being retarded [Re: polyspheric] #228561
02/18/09 12:43 PM
02/18/09 12:43 PM
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Bend,OR USA
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Quote:

Typo?
Intake valve closes sooner.


Both valves open sooner and close sooner in relation to TDC of the intake and exhaust strokes, if I am remembering correctly Either way advancing the cam, moving the intake lobe center closer to TDC makes more torque at a lower RPM and moves peak HP lower in RPM also, you gain bottom end and loose a little top end. A lot of the cam grinders will spec a cam with four degrees advance built in, say the cam is ground on a 110 lobe seperation angle and they will have you install it with a 106 intake lobe center So straight up off of the cam card could still be 4 degreees advanced


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: At risk of being retarded [Re: polyspheric] #228562
02/18/09 03:57 PM
02/18/09 03:57 PM
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Romeo MI
MR_P_BODY Offline
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Quote:

Typo?
Intake valve closes sooner.




Sorry about that... I just seen it... thanks for the catch

Re: At risk of being retarded [Re: MR_P_BODY] #228563
02/18/09 06:23 PM
02/18/09 06:23 PM
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Ont. Canada
10.90 Racer Offline
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Most recommend 4 deg advanced because everyone wants a cam that is too big!!!

Re: At risk of being retarded [Re: 10.90 Racer] #228564
02/18/09 06:48 PM
02/18/09 06:48 PM
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Newark,De
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hemi471 Offline
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Also alot of cams are ground 4 deg advanced, so when you install it straight up its advanced 4 deg. I called Comp Cams and found this,at least on the one they sold me.

Re: At risk of being retarded [Re: hemi471] #228565
02/18/09 07:15 PM
02/18/09 07:15 PM
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Shopping @ HoBo Fright
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Quote:

Also alot of cams are ground 4 deg advanced, so when you install it straight up its advanced 4 deg. I called Comp Cams and found this,at least on the one they sold me.


both my engle cams soild and hdy were ground 4 degree advanced.


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Re: At risk of being retarded [Re: 340SIX] #228566
02/18/09 10:10 PM
02/18/09 10:10 PM
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gulfport, ms, west mi
rowin4 Offline OP
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Thanks for the info, I've got a comp cam, maybe i should check with them on there specs. Thanks again



it's ok to butt heads, just don't do it with a butthead
Re: At risk of being retarded [Re: rowin4] #228567
02/18/09 10:18 PM
02/18/09 10:18 PM
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Romeo MI
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Yes alot/most cams have 4 degrees of advance ground
into them, I still advance them another 4 to 6 degrees
on top of what they say for the installed degrees,
specially on small blocks that need the added torque

Re: At risk of being retarded [Re: rowin4] #228568
02/19/09 11:28 AM
02/19/09 11:28 AM
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Oregon,USA
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RAT PATROL Offline
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Every motor is going to be different. I talked to Comp Cams cause my car won't 60' with the other Hemi's. They told me to leave it alone, of course I didn't listen. Advanced it 4 = 60' same (1.32) but MPH went down 2 and slowed a tenth. Cam is going back in straight up. Have cleaned the wax out of my ears. Still learning.

Re: At risk of being retarded [Re: RAT PATROL] #228569
02/19/09 11:55 AM
02/19/09 11:55 AM
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Eighty Four, PA
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Cam setting is based on the overall combo.From the engine build to drivetrain gearing,chassis and desired power range,using weight,HP&torque,gearing,tire size,shift rpm,trap rpm and calculated MPH.Other reasons maybe for piston to valve clearence and cylinder volume pressures.That a cam should be advanced or retarded,you must analyze your complete combo and calculate where your power and torque curve will best benifit your antisipated performance.

Re: At risk of being retarded [Re: MR_P_BODY] #228570
02/19/09 12:33 PM
02/19/09 12:33 PM
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emarine01 Offline
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If I have intake valve clearence to advance a 280/284@ .050 107 on 103 to 107 to 99 ,thats going 4 more advance for 8 total , is that better than retarding this cam 260/262 106 on 106 going to 108 2 degrees retard with 12 to 1 comp witch one is better , big cam lifts ,030 more> or should I just get another cam that falls around 270 on 108 or 110 and advancing it 4?

Re: At risk of being retarded [Re: emarine01] #228571
02/19/09 06:11 PM
02/19/09 06:11 PM
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Posts: 1,200
UK
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602heavy Offline
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Advancing the ICL will fool the motor into thinking it has a smaller cam , considering most cams have more duration than necasary (big is not always better) , then in most appliications advancing the ICL will yield more power as the motor will build more cylinder pressure.

I advanced the ICL 8* (108 lobe sep)& went from a 1.6 to a 1.5 60ft , fitted another cam (112 lobe sep) on the assumption the 108 lobe sep was dumping most of the nitrous out the tailpipes @ overlap , picked up another 2/10ths & got me into the 10s.

Last edited by 602heavy; 02/19/09 06:12 PM.
Re: At risk of being retarded [Re: 602heavy] #228572
02/19/09 08:04 PM
02/19/09 08:04 PM
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emarine01 Offline
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Thanks for the info, trying to get a good grasp on valve timing for my rig, I have been running 2 cams small and large and trying to figure it out by seat of the pants, Seems a lot of guys are running wide lsa with a lot of advance , still trying to get a feel for cyl preassure,lsa & advance, the simple thing is go with a 108lsa on 104 lots of cams built that way but not looking for much power under 5000, still dont know if 108 lsa in on 108 or 110 on 106 , which one is better for me? Sorry if I stomped on someones thread but the questions are closely related

Re: At risk of being retarded [Re: emarine01] #228573
02/19/09 09:05 PM
02/19/09 09:05 PM
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Posts: 1,260
Las Vegas NV
moparmanjames Offline
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Just a quick explanation of camshaft lobe separation, The tighter the lobe separation, the more peak torque you will have for a camshaft with otherwise all other specifications identical.
For example, say you have a basic cam, 230 @ .050"
and .500" lift with 1.5 ratio rockers.
If this cam were ground on a 114 lobe separation angle, you would have a relatively flat torque curve with good vacuum and idle behavior due to minimal intake and exhaust valve overlap.
Now take the same cam and tighten the LSA to 112*,
the torque curve has become somewhat hill shaped compared to before, with a higher peak torque but it drops off quicker as the rpms increase there is a slight lope to the idle.
Take it to 110* and now it's getting peaky and higher torque with a definite drop off not far past peak torque, a very noticable lope and idle vacuum is falling.
Now we go to 108* and the graph now looks like a mountain with torque climbing to a large peak fast but falling off fast as well, choppy idle from excessive overlap and we are needing to up the idle rpms to keep it running in gear with a stock converter.
This is due to closing the intake valve earlier and earlier as the lobes get closer together, this increases overlap so idle vacuum goes down but midrange power skyrockets. To compensate for losing power in the higher rpm range, we just increase duration to keep the valves open longer.
so you have to decide on an engine compromise between manners and barbarism.

This is a very basic explanation and wider lobe separation does have its place in performance, it's all in the application and what you are trying to do, but just remember the rule of thumb is the wider the lobe separation, the flatter the torque curve across the rpm range, so if you want a flat torque curve but also alot of torque then you must raise the cylinder pressure either with compression or forced induction or nitrous.

Re: At risk of being retarded [Re: moparmanjames] #228574
02/19/09 09:32 PM
02/19/09 09:32 PM
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Akron, Ohio
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I have always installed my solid cams a couple degrees advanced with great results. My new short block came with a roller cam by CamMotion, I called CamMotion and he said my 705/661 281/283 cam is on a 104, he had me degree it in at 106 as he thought 104 with my 500" 440-1 headed combo would be all bottom end and less top end so I put it in at 106, especially since I'm running a true 10.5" tire. We'll see how it goes.


1970 Challenger, all aluminum 528 Hemi, HDK suspension, Tremec 5 speed manual
Re: At risk of being retarded [Re: moparmanjames] #228575
02/19/09 09:48 PM
02/19/09 09:48 PM
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emarine01 Offline
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Nice post, thanks- My goal is to carry as much torque to 7k as possible with 12 to 1 comp my comp solid roller 260@.05 106 on 106 is a little too peekey , good @ 55 to 6k but falls flat by 6500 with big mud tires , the 280@ .050 107 0n 103 doesent have enough @ 5500 I think its too much duration for 12 to 1 trying to pick a cam in between around 268@.050 but cant get a grasp on lsa the 108 will still be peekey I think so I was looking at 110 and advanving it 4?

Re: At risk of being retarded [Re: emarine01] #228576
02/19/09 10:52 PM
02/19/09 10:52 PM
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UK
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602heavy Offline
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A cam ground with a 110 lobe seperation angle will in most cases be installed 4* advanced , this puts the intake centre line @ 106* & the exhaust centre line @ 114* , some say the reason for this is to allow for chain stretch , the cam card will say @ what CL the cam should be installed (if 112 lsa then they want it installed @ 108), is this what you're asking?

Last edited by 602heavy; 02/19/09 10:55 PM.
Re: At risk of being retarded [Re: emarine01] #228577
02/19/09 11:58 PM
02/19/09 11:58 PM
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Las Vegas NV
moparmanjames Offline
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Quote:

Nice post, thanks- My goal is to carry as much torque to 7k as possible with 12 to 1 comp my comp solid roller [Email]260@.05[/Email] 106 on 106 is a little too peekey , good @ 55 to 6k but falls flat by 6500 with big mud tires , the 280@ .050 107 0n 103 doesent have enough @ 5500 I think its too much duration for 12 to 1 trying to pick a cam in between around [Email]268@.050[/Email] but cant get a grasp on lsa the 108 will still be peekey I think so I was looking at 110 and advanving it 4?




So first, you say you want to carry as much torque to 7000 as you can, so does this mean you want your HP to peak at 7000 or do you want to shift at 7000?
I think you are on the right track with the 110-112 lsa with 270* or so @ .050".
If you can give me a run down of your engine I will throw it on my dyno program and see which cam will be best.

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