Archer

Guys -

Looking at the 440 Source Stealth heads, std casting vs. CNC ported.
Currently running 906 heads with mild porting and good valves.
Cam is an old ISKY grind, 280 duration/465 lift (I/E), and about 10:1 compression (TRW pistons).
RPM range, 2500 - 5800, with 3.91 gearing. .

So, how do I know if the CNC ported heads will offer any benefit over the "as cast" heads.
More worried about loosing low end torque with the larger runners, than any high rpm gains.

FYI, when I spoke to Edelbrock about their heads, over what I currently had, they said, it wouldn't make much of a difference (ie don't waste your money).

Thoughts?

Archer

RacerHog

Kind of depends if the short block foundation part is adequate? Flat Tops, Zero Deck, .040-.048 quench, and cam somewhere in the neighborhood of 208/221 Duration @.050 / 450/458 lift and a Lobe separation of 115 and if i recall that was with a 75CC Head Chamber... I think that put it somewhere around 10.5.0 on the compression ratio. But I'm getting old... lol
Keep us posted..... And Like I said,,,, This is only my opinion... But I noticed no one else jump in here and gave any input yet...
Cheers

Iowan

Unless you need work on the 906 heads I couldn’t justify the expense of the 440source heads as cast. Depending on how much work you put into porting your 906 heads but I'm thinking power increase will be minimal at best….

Archer

Iowan -

Yeah, that's basically what most guys are telling me. The 906s, are in good shape with what used to be called "street" or pocket porting.
I was thinking the CNC'd heads would give me more top end, which I really don't need these days. The only benefits I could see would be the smaller chamber, bumping up the compression and a weight loss.

So yeah, there's no valid reason for the head swap, except for "playin' around".

Bob -

They are flat top, notched pistons. I can't find the cam card, and it's an old grind, so ISKY s\doesn't have specs on it.
IIRC the specs at 50 were a little higher and the lobe separation a little less than 115.
But yeah, we're both getting old(er).

Thanks guys,

Archer

RacerHog

I did forget to add... More than likely it will mover the power band higher and knock out some of the low end up until after 2500 rpm if you just put the heads on with no other additions.

Archer

Bob -

That's kinda what I was thinking, and what I don't need.
Thanks.

Archer

RacerHog

Did a little poking around and found a little reading and comparison for you to mull over... Just some food for thought just in case you get the itch..... Cheers
https://www.motortrend.com/how-to/ho...hp-street-440/

Archer

Bob -

Nothing really new there. While the Edelbrock Performer RPM heads do seem to offer the most bang for the buck, they're just fugly. (I do like the angled plug holes for header clearance...) That's why I was curious about the 440 Source Stealth vs CNC'd heads.

The dyno results on that article are questionable (to me anyway), since a lot of the components used should favor a higher RPM range, and yet, the max TQ and HP were within factory spec.

Even with the 3.91 gearing, most of my street driving is under 3000 RPM, so even a 20 HP gain at 5600, isn't going to get used much.

Thanks, your help is always appreciated.

Archer