440 & 383 interchangeable parts

[69wannabe]

Thanks for the good debate guys. I think it is constructive and helps me learn some. 

Can I expect to get a horsepower boost if I replace my stock 383 heads with 440 "906" heads? They are a direct easy swap; right?

They are a direct swap but in stock form all the big block heads from 68 to 78 are basically within 5% of each other if you are comparing flow numbers. The 906, 346, and 452's are very close to each other in hp and flow numbers and for all the work that goes into swapping out a set of heads you would be disappointed in the outcome I am afraid. I pulled a set of 906's and had a good port and polish job done and retained the stock valve sizes and they worked ok but really didn't feel the impact it had on my wallet and all the labor it took to pull them and put them back on. If you decide to have the oversize valves (214 intake 181 exhaust) put in and then a street port and polish done you will see and feel the difference and put a good eddy RPM intake on there you will be proud of all the work that went into a head swap then but keep in mind that for a little more cash you may can do a nice set of eddy rpm heads that will flow even better. I only had about $650 in my heads but that was about 2007 and prices in parts and machine work have went up a bit since then. They work fine and I don't really drag race so for the street these cast iron heads do fine for me. I didn't have to hurry on my heads so I bought up the parts a few at a time and paid the machine shop for a few weeks along as they worked on them so it wouldn't kill my wallet to bad. I have been doing business with my machine shop guy for 20 years so he works good with me on my slow moving projects.

[johnnycharger]

I have the opportunity to buy a set of so called "new" 906 heads for $400. I am not an expert enough to prove their condition before i buy them. My heads are not in great shape aka the threads are kinda good/ kinda stripped...  I am just curious if I buy them if I will be only fixing my thread issue or if I will be getting horsepower. Am I better off buying $2000 aluminum heads?

[BSB67]

I have the opportunity to buy a set of so called "new" 906 heads for $400. I am not an expert enough to prove their condition before i buy them. My heads are not in great shape aka the threads are kinda good/ kinda stripped...  I am just curious if I buy them if I will be only fixing my thread issue or if I will be getting horsepower. Am I better off buying $2000 aluminum heads?

Personally, I would not buy and use a $400 set of heads unless I knew a lot about them.  And I don't mean asking the seller.  You might have 906's now, as they came on 383's as well.   Probably the single best thing you can do for your engine's performance is to put on a set of aluminum heads, and only purchase them after you remove the heads and measure where the piston is at top dead center.  Buy the head that gives you 10:1 to 10.5:1 compression ratio.

[Cooter]

I'd seriously consider adding another $500 or so and go with Aluminum. Iron have their place, but new aluminum heads have come way down in price.

[johnnycharger]

Thank you guys. I really appreciate your input. I will hold off and get the aluminum ones but I will have a lot to learn before I order them I guess...