Guys, looking to run a ms4 or ms3 on an lq9 stock bottom end with ls3 heads, will there be enough ptv clearance with a factory gasket? has anyone tried this yet? will be a carbed motor in a light *** sn95 mustang.

 

No LS3 heads have valves that are so much larger that I am completely sure the MS4 won't work with out alot of fly cutting. and pretty confident the MS3 will need to be cut for also.

 

How much fly cutting would we be looking at? not scared of it at all, some fly cutting and a thicker gasket should do the trick

 

I am running a l92's, ms3, flat tops with small reliefs with no issues. planned on milling them .030 too without hesitating

 

Do the L92s have the same 2.16 intake valve as the LS3s do? if so, how much of a guestimate do you think woulkd need to be fly cut as the MS4 is .649 on the intake side. Thanks for the help guys

 

yes the only difference in the 2 heads are the valve weight, id make sure id have the ls3 vales as they are lighter, anytime youre wanting to bring up the rpms for gains, its good to pay attention to valvetrain weight,the lighter the better, l92 valves are known to break.. if it matters i used to run the ls3 heads milled .015 with a .040 head gasket, on a lq9 this gave me a compression of 11:1. cam was a 235/239 .624 lift, i was border line on ptv clearance but the heads were setup with spring heights and spring pressure being dead on to what i am ( was ) looking for.. the exhaust side of the ls3 heads are whats important.. they definitely need a good porting

its not so much the lift as important to the duration!

 

Yes i do have the true LS3 lightweigth valves in these Skeet. does anyone know what is the max amount that CAN SAFELY be cut from the pistons?

 

When we make flycuts we usually try to go around .080-.090" and no more just to make sure the piston stays strong enough. We have cut more then that in extreme cases and been alright but I would try and stay safe with it.