I think you're making a mountain out of a mole hill here. Any aftermarket head (along with ported E7's and GT40's) is going to give you more than you experienced from those D8OE's. Stop procrastinating and just choose a set of heads, you'll be happy with whatever you choose. You could buy the 180's,run em, then spend another $1000 on the 200 or 215's and if you never put it on a dyno, you'd be hard pressed to feel the difference in the torque curve.

 

Yeah I was in a hurry and messed that one up, less valve overlap is higher LSA.

 

If you really want to see how all the different combinations behave get yourself a copy of Desktop Dyno and spend some time with it. The program is based around chevy motors so unless you input the actual head flow numbers it'll come up with relatively high output numbers, but nonetheless you will still see the relative difference in how the cams behave and such. Every engine displacement has what I'd call an ideal combo that produces a fat torque curve and somewhere around 1hp/cu-in, with bigger cams and heads the powerband starts to shift towards more HP at the expense of low rpm torque, and with smaller heads and cams the motor is just choked down to some lower output level. All these old Ford motors come from the factory in this latter state, the heads and cams are way too small to just let the motor breath and produce the power it should from idle to 5000rpm... which isn't an extreme performance level it's just something you would use if it was available. All the cam and head parameters have an effect on not only the shape and size of the power curves but also drivability and idle quality, so as usual the bigger and more radical you go the less streetable the engine becomes. EFI also has a harder time idling cams with lots of overlap so you may want to consider 110deg LSA the limit though that too depends upon the 0.050" lift numbers, at 200deg the motor should idle pretty good but up around 230 deg you're gonna have a problem obtaining stock idle speeds and will likely need to jack it up to 1000rpm... which affects the torque converter.
And the same goes for heads, with 351odd cubic inches under them you see increases in both TQ and HP all the way up to the 230-250cfm level, and after that the results start favoring high rpm horsepower.. though the negative impacts on low rpm TQ aren't as significant as it is with cams. But still if you're not going to configure the motor for big topend numbers then why spend more money on bigger more expensive heads. I'm sure that's what baddad is saying when suggesting GT40 heads and he's got a point, my argument is it might cost $600-800 to get a set of these ready to go so why bother when you can have brand new Dart or RHS heads for a couple hundred more. Of course if you can score a good set for $300 then it's a no brainer, these things work much better than any of the stock heads so you'll probably be happy with the results.

 

I'm getting the AFR 185s.


I called AFR and spoke with a technical represenative. The 165cc cylinder heads are for 289/302 on the street. The 185cc cylinder heads are for 350s on the street. If I were racing and needed the torque curve to extend beyond 6,000 rpm then the AFR 205s on a 350 cubic inch V8 would be a match.

 

I like Detroit iron.

I don't remember hearing if your engine has zero deck. If it does, I'd look for some good quench heads. I have an 86 Mustang with the E6SE heads and they make awesome torque.

On a 351, I'd be looking for C90E, D0AE, or D5AE heads. Especially the D5 heads. Install some Chebby 1.94/1.60 valves and do your porting magic and you're good to go.

Fergetabout shrouding. Ford actually designs some heads to deliberately shroud the valves. They had a patent on that concept. By shrouding the valve, it forces the fuel in the air/fuel mixture toward the center of the cylinder, giving a more even air/fuel mix in the cylinder. Otherwise, you could end up with a mixture that is rich on the intake valve side, and lean on the already hot exhaust valve side.

 

Those are all great cylinder heads but they are rare.

My camshafit guy at Schneider steered me into Edlebrock Performer/RPM 1.90"/1.60" valve cylinder heads.

If I came across a set of early 351W cylinder heads like you listed I would likely buy them.

My block has been decked. The previous re-build consisted of running one cylinder head with a few cc more of combustion chamber on the lower deck and smaller combustion chambers on the higher deck. I did not approve of that. I had the block milled straight and for the best consistancy of quench across the cylinders.

I have been playing with small block Fords inconsitatly for about seven years which is not very long. I have com across lots of '60s 289/302 cylinder heads and mostly late model 302 cylinder heads found on 5.0s and 5.8s.

I really like that idea about shrouded intake valves directing the mixture into the middle of the combustion chamber rather than it being mis-guided to the sides.

 

shrouding is bad, fords shrouding days were a band aid and mistake. modern head designs try to limit shrouding as much as possible. 4 valve heads have minimal to no shrouding. Early performance heads did the same, like the hemi and cleveland. shrouding causes restriction and turbulence limiting cylinder filling. anytime flow has to turn it slows down. It is hard on a inline 2 valve heads to eliminate shrouding and manufacturers must work within the engines design (unless starting an engine from scratch) proper swirl is accomplished by proper port and combustion chamber design.

 

The concept behind the shrouded valves on the E6 heads wasn't to force the mixture to the center of the cylinder (good luck doing that as you're not dealing with a static environment here with the piston moving down, then back up before the mixture is ignited) it was to force the mixture to swirl as the piston was drawing it into the cylinder, thus getting a better mixture. It worked to a certain extent at low rpms as these engines gave a better torque output at lower rpms than the others. Now the spark plugs in these are located closer to the center of the cylinder, that may be where the confusion about the "center of the cylinder" comes in.

 

I have a set of worked over E6 heads that were on my 5.8 for a while and when I took them off the swirl pattern was clearly visible in tan colored deposits in the combustion chamber. The design works as advertised because that motor made great TQ but even with the ports hogged out as much as I dared it didn't make exceptional HP. The pic below shows the E6 chamber on the right and an E5 on the left which is similar to the E7, the bottom series of pics shows the intake valve at 1/2" lift in both heads and you can clearly see how much more shrowding there is with the E6 design.




If you look at any of the newer performance heads they all have irregularly kidney bean or figure 8 shaped combustion chambers now, they're getting away from the open D chamber which really doesn't do much besides not shrowd the valves. The pic below shows a Dart Iron Eagle with 2.02/1.60 valves on the right next to an E7.