.60 point of compression isn't much. I'll give you 5 hp for that. Now take a look at the Holley 17 degree heads that gives up .25 point of compression and still makes more than the Can'tfields. Bottom of the barrel.

edit- calculations of adding .60 to the Canfield numbers came to 378 hp.

 

On a 347 you might wanna go bigger than an AFR 165. The RHS heads are good, but the smallest head is a 180cc intake port, so they're almost a bit big for a 302, but will work very well on a 347. AFR 165's on a 347 will make excellent power, but that longer stroke and a smaller head will make a crapload of torque at very low rpm, and traction may become an issue. Sometimes there's a good reason to soften up the bottom end just a little bit, so you don't spin at 1,500rpm. Small heads ona 347 with tall gearing would work well though, or lower gearing and some big tires and good suspension

 

a stock 5.0 intake is extremely restrictive anbd theres a substantial boost in power over the stock efi setup i believe the stock 5.0 ho cam is about the same specs as a 289 hipo cam so really the number wouldnt be too far off and most claim the 5.0s were under rated but quite a few ponies. plus thoose little cars scoot to begin with. theres a 5.0 user named quik he was on pinks with a 240sx or something like that? he was running a 13.38 with a stock cam,head,a short belt,k+n headers flows dumped and 3.55 gears granted it was a coupe and it was either an 87 or an 88(they were faster stock than the 89+cars but its not to shabby for a 225hp car now is it?

 

rmodel, the problem i see with that article is that you get a huge boost in power with the AFR's, some headers and a carb but...you gotta drive it to 6200 to get it. Torque curve is also higher in the rev range.

I'm just not a fan of trying to bolt power onto an engine that hasnt had appropriate preparation elsewhere to handle it.

to dcohen, IMO the choice of heads depends on the desired outcome (where you want the power, how hard you intend to drive it etc) and the combination of all the other components. I have no brand preference...all the ones listed are good (they have to be because its so competitive in that market now)

 

Call me crazy but Jeg's has some heads for the small block ford that are pretty darn good for the price, great flow numbers, partially CNCed, 7/16 studs, 2.02 intake that work with stock pistons up to 550 lift. I've used these before and they are SOLID! Did my own port and polishing on them... turned out awesome! I have zero dyno numbers to back this but i felt i had noticeable better torque with them then i did with my old edelbrock rpms. And oh yea, AFR are art, can't ever go wrong with them!

http://www.jegs.com/webapp/wcs/store...52888_-1_10187

 

What do you guys think about Hollley heads? I have a set on my race car and seam to work pretty good.

 

Crazy?? nah,, it's all about "bang for the buck" John...

 

Holley heads are decent, but not the best out there. It depends on the head and what you use it for though, like AFR's heads are good for street, Edelbrock's heads are good for race etc