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

The 104ICL is going to open the intake early. No way to know unless you measure. You can get lift at TDC info from the cam manufacturer to get a good benchmark and measure P/V before you ever assemble/disassemble anything.

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

According to the cam card,

IN opens BTDC @ 23.5
IN closes ABDC @ 51.5
EX closes ATDC @ 15.5
EX opens BBDC @ 67.5

The valve sizes are 2.065 Intake, 1.88 Exhaust

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.

http://kb-silvolite.com/images/spiston/L1448.gif

these are the pistons that are in my motor. hope the link works.

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.