I'm doing a mild 5.8 build this summer and my plans are: under drive pulleys, gt40p heads, intake mani, headers, and custom 2.5+ exhaust. My main question is when I install the gt40 heads, do I use headers made for a 5.0 truck? Also do I need a mustang intake mani? I'm trying to use as many mustang parts as I can cause I can find them used and cheap.

 

A 351 block is 1" taller so you need 351 headers.

If you want to use as many mustang parts as you can than build a stroked 302.

 

5.0 shorties will probable work, the bbk shorties or summit brand. Any headers that would fit your truck now will still fit with those heads, only difference is with the p heads you may run into spark plug to header clearance problems. Gt40s are te safer bet

 

Skip the underdrive pulleys you're not building a 6000rpm motor, you want truck specific longtubes and you don't need or want a Mustang intake, a Typhoon would be the most cost effective replacement to make the best of those heads, but you'll need 24-30lb injectors to feed it and a tunable EFI system to manage it.. which means a MAF conversion is in your future.

 

Con, do you know what the box code is on the computer for speed density? I just got my motor in, 351w, world windsor jrs, 1.6 rr's .030 over and i didnt seam to get much power from it... I think i needa tune...im really itchen to almost go carb, hate on me all you want. The shop i was talkin to a little bout a tune said theyd need the code to see if thy could tune it or not... regardless im sure itll be outta my price range. Im definately not going mass air, and i dont know if the sd will really get me where it should be and the quaterhorse seamed a little to complicated for me to be playin around with. Ive got no o2, carbon can, egr, smog pump, cats, etc etc etc. sorry to but in on your thread here but it kinda goes along with the tuneability of your sd if you were to keep it with your mild build. All i did was a real mild build but i really didnt get much power...

 

You didn't get much power because the bottleneck in that motor is the stock cam.

 

I was under the impression theres no point in changin the cam in sd motors because you really cant do much with it. Id considerring takin the radiator out and sliding a crane 444232 in there but i dont feel like orderring and paying for another set of hardend pushrods and cant afford to have the truck down for any duration of time... Daily driver.

 

What gave you that impression and who told you hardened pushrods were needed?

The cam is the single best upgrade you can do to any of these trucks.. SD or MAF, and there's no need to change the pushrods at all when changing cams, with a flat tappet you do need new lifters however but they usually come together as a kit.

 

hardened pushrods were needed for the guide plates for the roller rockers and i thought that the cams lift may change the pushrods length i'd need to keep the valvetrain geometry in spec.
If your saying that changing the pushrods would definately not be necessary from the lift of the cam could i leave the preload adjustment the same as well? SD friendly? http://www.lunatipower.com/Product.aspx?id=2513&gid=309

 

Do those heads have stud mounted rockers? I thought they had pedestal like the factory head.
Cam lift won't affect pushrod length, the base circle for different flat tappet cams is supposed to be the same.

 

GT40 heads, even the GT40X or Y aluminum heads have pedestal mount rockers. No need for hardened push rods.

 

My rr on my world windsors are stud mounted and use guidplates.