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I have flat top pistons in my 468, along with closed chamber heads. I am just wondering if there would be any P/V problems with this cam, i know there is no way to be sure until you measure it, i was just wanting some opinions.


The cam i was wondering about is the 402A7LUN

* Advertised Duration IN/EX: 288/296
* Duration @.050 IN/EX: 255/263
* Gross Valve Lift IN/EX: .612"/.630"
* Lobe Sep Angle / Intake Ctr Line: 110/104
* Valve Lash IN/EX: .024"/.026"
* RPM Range: 3000-7000

Thanks Brian
 

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What size valves? Even if you have a enough depth, make sure you closely check the radial clearance in the valve pocket. 2.19's or larger get pretty cozy in lo-perf piston valve pockets.


JIM
 

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I have flat top pistons in my 468, along with closed chamber heads. I am just wondering if there would be any P/V problems with this cam, i know there is no way to be sure until you measure it, i was just wanting some opinions.


The cam i was wondering about is the 402A7LUN

* Advertised Duration IN/EX: 288/296
* Duration @.050 IN/EX: 255/263
* Gross Valve Lift IN/EX: .612"/.630"
* Lobe Sep Angle / Intake Ctr Line: 110/104
* Valve Lash IN/EX: .024"/.026"
* RPM Range: 3000-7000

Thanks Brian
What piston?
Flat top or dome has nothing to do with p/v clearance, it is the relief.

Check it.
 

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Easiest way to do preliminary checking - assuming motor is already assembled. Bring #1 to TDC. Take rocker off #1 intake, get measurement off of fixed point on head to retainer. Open intake valve until it hits the piston, take new measurement, this is your P/V clearance at TDC. Hopefully it is at least .250". For comparison, when I assembled my motor, I had .400" P/V using the above method.

Using A Comp XE as comparison, closest lobe is XE290 [290/252/.614]. This lobe will have .115" lift at TDC when installed at 106ICL. Backing out .024 lash and mult x 1.7 = .155" valve lift at TDC plus .060 clearance = .215" for this lobe. The Lunati may be a little faster and is 2* more advanced, so you will have to check. But my guess would be .250" or better and you will not have a problem. It is real easy to check though.
 
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