Heads, how much gain?

mopower440 said
The engine in my dart is a 1975 440:
.030 over
Trw L2355 six pack pistons
MP 284/484 cam installed 2 or 4 degrees advanced. (cant remember, been a while)
Bone stock 452 heads
Compression is 9.4:1
Stock intake
Demon sizzler thermoquad
Hooker 1 7/8 fenderwell headers
3000 stall convertor.

Thinking of getting some heads. I would not be able to afford any porting to the new heads so they need to be good flowing right out of the box compared to my stock 452 heads. SO, if i got a set of new edelbrock heads or something similar, what kind of HP and torque gains could i expect? They say the edelbrocks and all these other heads right out of the box outflow the stock heads ported to the max...Is that true?

First, nope, Edelbrock RPM heads do not out flow stock heads ported to the maximum. But for your purpose that should not matter.

To your question about horsepower and torque improvement. I do not have a stock head to an OOTB RPM head test but the following dyno results would be similar. Here we have a low compression 440 using a MP 509 camshaft where we switch from a pair of stock 906 heads to a pair of mildly ported 516 factory heads. The 516 heads out flow the RPM head a little in the lower lift ranges but the horsepower increase in switching to the RPM should be similar. Post line #43 shows the dyno run previous to the head switch and #44 shows the increase with the head switch.

http://www.forabodiesonly.com/mopar/showthread.php?t=249866&highlight=low+compression+dyno+440&page=2

Here is a 440 shortblock very similar to yours with cylinder head and camshaft changes done on a dyno.

http://www.forbbodiesonly.com/moparforum/showthread.php?64775-Pop-s-440-is-near-ready-to-dyno&highlight=pop%27s+440

As others have cautioned, the Edelbrock or any other head should be checked and prepped before use.

I can email you OOTB head flows of stock heads and RPM and Stealth heads and compare them to ported iron heads but for some reason I can't download them on the forum.