Has anyone put over size valves in the 2-valve PI heads? All I can find are Manley valves in 45.5 mm. I'm no pro but, the heads look like they can fit up to 1.90" intake-and 1.50 exhaust in them. Does anyone els offer bigger valves, or am I limited to these Manley sizes?

 

45.5 mm is only 2.8 mm smaller than 1.90" though.

 

Yes but, 45.5mm is only 1mm larger than stock, I believe. which means I'm not ceartain but, I know I'm pretty close. $$$ on a valve job for 1mm? Weak.

 

If I increace my valve sizes, I should still be able to use my stock cams and some slightly larger fule injectors with no computer modifications, right?

 

Check out the Mustang sites, mucho info with the mod motors there.

Many manufacturers (unfortunately no major ones) already sell the heads with the larger valves. You can use any modified PI head, as long as you have the intake for it.

IMO, if you're gonna enlarge the valves you should also get different cams and upgrade the ECU programming to match. The injectors may be subjective, but I'd go with a larger injector as well.

I have read it online in some forum or magazine (how's that for specific, I read a lot) that when you upsize the head (porting, polishing, et al) you should recalibrate the ECU. If you mess with the head you should upgrade the cam to match.

-Kerry