Anyone here used Howards roller cam in the 400m engine ? and would the 2v heads handle 600 in lift on the ex valve with maching springs ? how much lift can i go with these heads they have been milled about 2.mm and the block milled about 0.25" i am going to use 351c flat tops in this motor

 

2V heads flow drop off above 0.550, however since your valve wont be at max lift all the time, you'd probably want to gasket match port heads, minimal 3 angle valve job (research throat cut), and blend the VJ to the chamber to keep up with the cam. What cam did you have in mind? If its the 225/229 @0.050" you'll want a stout drivetrain.

 

yes it is the 225/229 @50 cam my heads have alredy been port matched with the edelbrock manifolds and the exhoust manifolds but im going to use headers im just worried if the valve to piston clerance will be to little ..

 

...so don't try to taste it - it's real salty too. A little trick that I've read about would be to mock the heads up using the locating dowel pins, but without head gaskets, and assemble the intake valve with tester (weak enough to depress manually) spring and measure from 20 BTDC to 20 ATDC and record your measurements. Remember add in the amount of final head gasket thickness to these measured clearances. The advantage of doing this measurement in clay is you'll be able to evaluate the P-V clearance of the valve relief of the piston. Fortunatly you'll only have to measure the piston-valve relief clearance once as long as you use the locating dowels. Then you can move on to your crank sweep (20BTDC to 20ATDC) measurements. I'm curious to what piston you're running - as far as the pin diameter goes.

 

Im curantly running dished trw pistons 0.30 with the original wrist pin but im going to use flatt top trw pistons with the .912" pin compression dist on both sets is 1.647