When I swapped from my 915 to the normal 440 source stealth heads my car picked up .2 in the 1/4. From what I've found online researching is the basic stealth heads flow around 268 cfm and the CNC version flow around 320ish. I have no idea what my old 915 heads flowed, they were pretty stock with a home port job done. Has anyone swapped from the reg stealth heads to the CNC version? Just curious as to how much I may be able to pick up with the CNC version heads. I'm looking to build a stroker in the future, but don't have all the coins at once to build it, so I thought maybe upgrading my heads now will be one less piece I need down the road.

I don't have an answer for you, but I would be interested in knowing, as well. I have a set of Stealths on my Bee.

I have the CNC'd Stealth Heads on my '69 RR. 4.30 gears, 3800 RPM converter. M & H 275-60-15 stickies, and SS springs. I had one track day at Maple Grove where I made 9 passes and a bunch of changes. When finished, the best pass was an 11.62 @115MPH. My 60' times increased by a tenth over the best pass ever.

The engine is exactly the same as the one I replaced, except it's now a stroker with the Stealth Heads. The first engine was 440 CI with Ported 452's that had 2.14/1.81 valves. That engine ran a best of 11.54. Don't remember the MPH.

I believe there is some more to gain with the new combo and some tuning, but the overall gain was not what I expected. The good news is the heads look stock when painted. The bad news...if i had spent some additional dough on better heads, I'd likely have a 10 second car instead of an 11.60 job. Since i have no roll bar, it's not a big deal. Ultimately, the Stealths are a good intro head. If you're looking to go all out racing, there are likely better alternatives.

I too am interested in a direct comparison of the CNC's vs unported. Good luck.

What cam in the 440 and in the stroker Tommy?

find some info on stealth lower lift flow numbers. from what i've seen that's the problem.

Maybe the valve job?

From my bench last Friday.... New head, ootb, stealth valves
and valve job. 4.375 bore, 28" test pressure;

Lift........ In/ex
.100----65/50
.200---144/104
.300---207/139
.400---235/168
.500---247/183
.600---250/192
.700---253/197

I've had a few sets of these come through the shop over the
past few years, and on my bench, mid-250's on the intake is
pretty typical for them in ootb form.

Rule of thumb is 2 hp per 1 cfm increase. So if the ported heads flow 50 cfm more than the unported heads you would be able to see up to 100 hp gain. I've run this test a few times and the rule of thumb is accurate as long as everything else on the engine can support the power increase.

are the new edelbrock rpm's much better?

Same head, same port as above, but with seats recut, mild
back cut on valves, and the bowls and short turns blended.
No rework on the pinch area or around the guide boss.

Lift------in/ex
.100----70/56
.200---146/105
.300---207/142
.400---244/168
.500---267/186
.600---271/201
.700---272/214

Ootb RPM head, ede valve job & valves
Lift-----in/ex
.100----67/50
.200---141/106
.300---209/144
.400---245/170
.500---269/186
.600---275/196
.700---278/201

Just keep in mind, not all ports on all heads flow the same.
These numbers are what these particular ports flowed on
these particular heads.

good to see you posting, don't be a stranger

For comparison, here are some numbers for an Ede E-Street
75cc head. The 75cc chamber definitely has more valve shrouding
compared to the 84cc heads, and has a noticeable impact on
the low and mid-lift flow numbers.

Ootb head with ede valve job

Lift-----in/ex
.100----62/52
.200---122/100
.300---183/137
.400---230/167
.500---262/185
.600---275/195
.700---282/201

From the same flow bench, here are some numbers from some
MCH CNC ported stealths. Stealth valves with back cut, MCH
valve job, full CNC ported, std port size. Average flow for one
left and one right cylinder.(#1 & #7)

Lift------in/ex
.100----70/60
.200---161/113
.300---222/143
.400---263/169
.500---289/189
.600---305/205
.700---309/215

We just ran a 438 inch low deck motor with 75 cc Edelbrock RPM heads and it looked to me like the heads wouldn't flow as much as the "classic" RPM heads. The power numbers were down a bit too. The flow numbers on the Edelbrock website are identical, but it didn't look to me like the 75cc casting would flow as well. Your post is the first set of numbers I've seen though.

i have run both stock Source heads , home clean up , and now CNC Source heads .
On a 440 ci RB +0.055 bore . Solid flat tappet cam 258@050 - 540 gross lift (0.020 lash) , 10.75ish:1 comp
Best ever pass on old heads was a 10.994@120.66 . Only ever ran 1 10 second pass mostly ran 10.10/18 range
With the CNC best pass is in my signature - 10.88's . In fact at a street meet last night with no track prep I ran a 10.893 with a PB on the sixty of 1.497.
Currently has a Eddy Victor manifold , gasket matched only , with Prosystems HP1000 carb .Mostly ran a M1 single plane and sometimes a BG 825 on older Source heads - BUT I had also run the Victor and HP1000 for minimal gains . On the chassis dyno there was about 30RWHP gain . This was all in flow - as the gain was in the swap from the 825 to the HP1000 . Timing needs did not change and only needed I think 1 more jet size in the rear .
I know I need more cam but I am not legal for sub 11's and I do have a another block that is calling out for a 4.25 crank kit
I am very happy with the result . are they a race head NO are they a good performance head YES with the proper prep . The straight plug is really nice too .

Tex

Here's some numbers from a random port on the standard stealth that Brian from IMM flowed for me. This is a home port work that I did.

What he said!

Matt, Both engines ran the Comp Cams .557" lift street roller (23-742-9) is the part number. I love seeing the real world numbers for flow on these heads. They confirm what I thought was the case. Does anyone have flow numbers for 906/452 heads, ported with large valves? It would be nice as a comparison.

i have a set of iron stage 5's that fast68plymouth tuned up.

lift-----in/ex
.1------72.5/57.2
.2-----148.2/117.1
.3-----212.2/168.2
.4-----256.3/200.0
.5-----278.7/202.5
.6-----290.2/204.9

Great seeing you posting Dwayne.