Lift on cams.

[gafletch]

Let's say a cam has an intake lift on a hydraulic flat tappet cam .510 and exhaust lift .525.
  What characteristics are different than a .525 lift on both intake and  exhaust?

[Chryco Psycho]

Odd usually the intake has the higher lift , the intake valve is much larger & could touch a piston without reliefs
The intake side relies on vacuum & therefore is less efficient so usually the duration will be a bit longer & lift higher to aid intake flow , the exhaust side relies on pressure to move the air & is much more efficient so the valve is smaller & duration can be less & still remove all of the exhaust

[gafletch]

http://www.lunatipower.com/Product.aspx?id=4002&gid=363
  Senior Neal, this is what I was referring to. The int/exh gross valve lift is  listed here as .520/.547.
Intake is lower,  or am I reading it wrong?    Anyway, why not just match the high lift numbers for int. and exh.? What does the lower number do?
Thanks, Greg.

[1 Wild R/T]

Your reading it right... Actually higher lifts & longer duration on the exhaust lobe is pretty common anymore.. While the logic of exhaust being forced out seems to work dyno testing & cam tests have shown that the exhaust on a BBM is a weak point so increasing the lift can balance the flow... 

[gafletch]

http://www.lunatipower.com/Product.aspx?id=2339&gid=362
Neal, what do you think about this cam for my 440?
I'll have rpm heads and intake, .040 over bore, Doug's Headers, 410 Dana, MSD ignition, Holley 750.

[Chryco Psycho]

That or the 10230704 should work well with what you have , I assume you have enough stall or a 4 spd ?

[Strawdawg]

Carb is smallish for that cam.  Otherwise looks good to me

[Chryco Psycho]

I agree , a Proform 850 would be my next upgrade

[gafletch]

Auto with 2800 stall.

[gafletch]

I'll call the Lunati-cs today about the ...704 cam. Do we get any discount there? Gratias, Neal.

[Chryco Psycho]

I would use the 704 cam , you do not have enough converter for the 705 , the problem comes in when the converter locks too early before the engine is into the power band & has to struggle to get into the powerband .
 You can can ask about a discount , I have been dealing with Steve Slavik for years , or jeff , all they can tell you is no !!

[gafletch]

I spoke to Mike. No discount but he agrees about the ...704. I'm getting lifters and timing chain too. Thanks.

[gafletch]

Hey, Neal and peers. With these heads, rpm performers,  Edelbrock's SITE recommends Champion rc12yc plugs. But one of their techs asked what compression I'll have and recommended rc9yc plugs at 10.5-1 comp.
Can you offer your suggestions? Thanks. Greg

[Chryco Psycho]

Alum heads can pull a lot of heat away from the plugs so generally you need a hotter plug but it is a balance between fouling a cold plug & detonation& other problems with a hotter plug , so trial & error I guess

[Chryco Psycho]

This should help , higher # champions are hotter so 14 is hotter than 12
http://matchlessclueless.com/mechanical/ignition/spark-plug-temperature/