My heads flow.
.500----------274-------183
.600----------291-------193
.700----------295-------199

The old cam had peak lift of 0.578" with the 1.7 rocker.

That massive air box has a large K&N in it. The whole induction system was only down 2-3 kpa at 6,000 rpm including the filter. The opening into the airbox is 1.5" x 9" which is bigger than the 3.75" opening inside the box. The 3.75" opening is the choke point but I cannot do anything about it because that is where the filter mounts and seals. Not like it is a restriction anyway. That little ski ramp lines up perfectly with the hood gap and at high speeds the IATs are near ambient temp. I have considered adding some kind of sheet metal or fiberglass box/scoop to seal the air intake opening to the hood and block off heat from the radiator. I have a spare airbox to play around with when I have more free time. I have also considered cutting a slot in the leading edge of the hood, creating a functional ram air setup. I really do not think it would even be all that noticeable.

The filter is 12.5" long and 5.25" diameter. It has alot of surface area. I ran the new K&N filter close to 30K miles before I cleaned it. It looked terrible but was still not choking the engine at all.

 

I already have the Mercruiser MPI dual plane marine intake on the 383. I milled 1" off the plenum divider and it is ported and port matches to the heads.

I placed a few orders on Amazon today. The 1200cfm 4bbl progressive linkage throttle body should have a very nice feel to it. Not too jumpy around town but not too restrictive either. I would have loved to have gone with the 3.5" tall Spectre plenum but I had to go with the 2.25" tall one. The 3.5" would have hit the doghouse cover and firewall. I think she will be a beast when I get her back together and running and keep her perfect street manners. The cam will only be 212/224 @ .050 at low-rpm and its in a high compression 383 afterall. I will flip that 700r4 geometry correcter upside down and hook the cruise control cable up to the kickdown stud so that I can keep cruise.

 

I only even mention the air intake side of things because some people on here seem to believe the stock air intake works so well you will not find gains. Could not agree less. The stock GM crap is all about keeping the car quiet and making it easy to assemble at the plant. My Vortec 350 gained over 20 hp at peak and over 30 hp over peak ditching the crappy stock system for a well thought out pieced together custom 4" setup and 100mm MAF. That was running a 80mm throttle body even. The little 300 hp marine cam also stopped making power at only 5,000 rpm. Point is the smoother you make the air flow through the system, the more airflow you can get into the engine, the more power you can make. PERIOD. Your engine would make the most power if it did not even have an intake in front of the throttle body. Probably even more without the throttle blades or shaft in the throttle body restricting the airflow. Not practical but you get the idea.

 

I'm not sure if you've mentioned it or not but are these Factory iron Vortec castings?

 

Nope. Assault Racing 205cc castings off Amazon ported by Lloyd. With 2.02/1.60, 0.100" longer valves. Double springs. 7/16" screw-in studs and guide plates. Topped off with standard body Scorpion 1.7:1 7/16" rocker arms. Hardened pushrods. No self aligning narrow body rocker garbage in this engine. I had to get creative with the valve covers by switching to short perimeter bolt valve covers that are slightly taller than the center bolts and grind on the a/c bracket to get it to clear the taller covers. The assault castings were drilled and tapped for both center bolt and perimeter bolt valve covers.

 

Wow, that's an impressive set of heads! Did they come with the valves or were they something that Lloyd installed? Lloyd has told me of some of the cheaper Chinese casting (not sure what these are) that work damn good with porting! We had discussed it for a SBF build that I was thinking about once. I ended up getting a set of TFS TW heads for that and cleaning up the ports a bit myself but honestly for the money I may end up sending those to Lloyd as well before it's said and done. That's a lil .040 over 5.0 with an Anderson N51hr cam. Should be pretty stout for a little engine and it may end up as a 333 before it's said and done. That's about as far as I really want to push a stock 5.0 block.

 

Lloyd did a valve job on them but the valves were from Competition products. Seem to be holding up well in my friends race car with much higher spring pressure and rpm so I figured they would work for a street engine.