I currently run a set of unported 915s on my 440 (1970) which gives me a rather high compression (not sure about the exact number).

I have the chance to get a set of ported 906s (by Koffels place). Is it worth the swap? Unfortunately I don't have any flow numbers but I'll try to get pictures.

The ported heads will out perform unported heads even with the compression change. You could have all the compression in the world but if the heads don't flow that compression is wasted.

I think the compression difference is only about .6 a 906 will out flow a 915 by a bit anyways a well ported head will make a lot more power.
and make way better use of a bigger cam, intake and headers/exhaust.
and be a bit more fuel friendly.

Here are some pics of the heads:

port window size looks pretty big..

cam right now is a .509 but I'm debating if I should change it..

I'd run the 509 with the 906 heads. Those ports look pretty nice.

Depends on the price, for the same dollars I would port the 915s and run them with zero deck and a .038-.039 head gasket,that has always been a good setup. The 906 look like they still need work, if you end up with a grand in them I would buy performer rpm of 440 source heads.

With the 915's you capitalize on quench to run more compression without ping. I guess it depends on what you need? All out power or more efficiency? It depends on your deck height whether you are cashing in on the quench or not.

Sheldon

What kind of work would be needed before I can run these heads? obviously some valves and springs..

As said you'd lose a slight bit of CR but gain ALOT of flow going from the unported 915's to the ported 906's. I'm assuming you dont have quench with the 915's but if you do have .040" quench I'd for sure stay with the 915's. Why are you wanting to lower the CR? Is pinging forcing you to compromise the adv curve? I'd keep the 915's as the ported 906's wont be cheap & if I wanted to step up I'd go with a set of mildly ported/blueprinted eddy or source alum heads which would give way more flow & the alum would likely solve the pinging issue

I need 93 fuel otherwise it would ping when I floor it. Haven't openend the engine yet so I don't know if it's 0 deck or not or if i have quench.
I'm trying to get a good deal on the heads and the rockers.. if I end up not using them I could always sell them again.

When you pull the heads check the depth "in the hole" if they are zero great you had quench & it wasn't enough... Lowering it should help... But if they are .020 in the hole changing the a steel shim gasket might be your best option... sure it'll raise the compression slightly but you'll gain quench... To be pinging with a .509 cam & 93 octane you must be running some pretty good compression...

If you can get your quench to .035-.040 with the 915 I would stay with them. If the quench is .060-.080 it with ping like a SOB, if you cannot correct that then the 906, eddy 440 source heads would be the way to go. The 906 you show need $500 spent on them for valves, valve job springs, retainers, at least so if you get them cheap maybe. I would not waste my time for how cheap the eddys are, plus you get hardened exhaust seats, but that is your choice, do the math.

915s and 906s have basically the same ports. So ported 906s by a known entity like Koffels will make more power than the stock 915s. Do the Crane rockers come with the heads? That may make it worthwhile to buy the heads even if you don't use them.

As far as price goes, if they need $500 worth of work they have to be less than $500 for sure and I'm thinking more like $200, more if the rockers come with them.

R.

price would be around $500 including rockers..

a member here said that the casting is an f-casting which is supposedly better than other castings (I thought all 906s the same). what does that mean? F for 1970?

I Never heard of that. Everything that I have read until this moment says all 906s are the same.

R.

hi, all 906 heads are not the same!!!! there is a R, M ,F and rare C letter cast on underside of intake runner.on a flow bench, at .500 lift all are pretty close same flow.. in the mid lift area, -.100 to.400 is where the main difference is.the flow curve has a noticable hump in the curve. mopar race manual states, the head with humped curve will provide more air to cylinder.as for flow , the R is the least the C is the best. most are usually M or F. so it runs, R,M,F,C,
I have had all on a flow bench and used on various engines.