MustangWorks.com : Ford Forums - View Single Post - SystemaxII intake and Box stock RPM heads

Rick 91GT · 01-17-2002, 04:51 PM

The Holley lower is just about a 1262 Fel-Pro, so if your heads are not ported to a 1262 there will be a step, this will create turbulance and cause a loss of some power..how much, I really don't know. However you should see a gain in power switching to the Holley over the GT-40.

I know I needed a 1" spacer with my fabbed alum valve covers and I had to grind down one of the bolt heads to get it not to rub...

01-17-2002, 04:51 PM	#2
Rick 91GT Procharged! Join Date: May 1999 Location: Hanover, PA Posts: 1,539	The Holley lower is just about a 1262 Fel-Pro, so if your heads are not ported to a 1262 there will be a step, this will create turbulance and cause a loss of some power..how much, I really don't know. However you should see a gain in power switching to the Holley over the GT-40. I know I needed a 1" spacer with my fabbed alum valve covers and I had to grind down one of the bolt heads to get it not to rub... __________________ *D/R 10108 NMRA Drag Radial, 25.5 chassis, F1R* *Check out RNH Performance Performance Engines and Custom Fabrication.* *From Mild to Wild we can build what you want, when you want it.* FOR SALE Stainless Steel Torque Box Supports