Cam grind thoughts

[jdscofield]

So I read this article from car craft, "hemi power from your Chrysler 400 for half the cost".  Reading through the article, I realized their build was pretty similar to mine, with the exception of shaving the heads/intake and cam grind.  As it sits, I'm at 8.75:1 compression.  I spoke with the guy from 440 source and he said if I pick up a set of their heads, it will raise it to 9:1.  The current cam grind is 235/235 475/475.  The one carcraft installed was comp cam k21-600-5, 279/296 486/473.  I'm wondering what your thoughts are if I install this cam.  Would it rob me of vacuum to where my brakes are useless?  Would it function well with stock heads or would I need the stealth heads?  If I need the stealth heads, should I get the cnc ported heads?  All input is appreciated

[Challenger340]

Magazine articles are all fine & dandy, but it's not so much what they DO tell.... as what they DO NOT, and typically there can be at least "some" marketing bias involved.
NOT saying there is in the particular article you mentioned as I have not read it, just say'in.... it is good idea when reading ANY such article to keep it in mind ? but I am guessing if the article is a few years old it may be CompCams "Thumpr" series Cam related ?

IMO, depending upon tire/gearing/stall speeds and the rpm range you are targeting.....
A .25 point gain with the Aluminum Stealths at 82-83 CC's "as cast" to 9.0:1 will do very little, versus 8.75:1 from your current cast iron heads, and potentially may feel like a step backwards due to the aluminum heads greater dissipation of heat during the combustion process versus cast iron, down at low 9's:1 compression ratios.
In my experience, aluminum heads just don't work well at low 9:1 C.R's with std gearing and street rpm's.

I feel(just my opinion), when switching to an aluminum head from cast iron, a mininum C.R. increase of at least 3/4 point is highly adviseable for best results, and even that number assumes retention of the same Cam events to maintain pressure.

Edelbrock E-Street have a 75 CC head that may provide a more conduscive C.R. bump when moving from cast to aluminum heads, and an overall power increase where your 235* @ .050 Cam can exploit the enhanced flow potential mid-upper rpms.

As far as any Cam "switch" from your current Cam to the CompCam 21-600-5, it would be nice to know your gearing/tire ?, Auto/stick ?, Headers ? etc., etc. how you are calculating your current 8.75:1 C.R. ?) so Firefighter2931( Ron) or BSB67 can chime in with some real world experience, those guys are really good.

[jdscofield]

Magazine articles are all fine & dandy, but it's not so much what they DO tell.... as what they DO NOT, and typically there can be at least "some" marketing bias involved.

Your quote is exactly why I posted.  It never said if the motor was installed when on the dyno.   So it can pull those numbers all day long, but if I can't stop, that hp and torque isn't going to do me any good.

As to my build, I can't verify because the douche engine builder never supplied me figures on paper.  Took him five months to just give me figures over the phone.  The build should be as follows:
400 bored .30 over, hypereutectic pistons, the above mentioned cam, stock 400 heads, edelbrock dp performer rpm, Holley 750dp, long tube headers, flow masters. He told me the compression was 8.75:1.  However, I don't know how to verify.  Currently, backed by a 727 with shift kit  and stock 8 1/4 rear end. 

The plan is to install locker or posi , 2700 stall, and either 3:55 or 3:91 gear.

[jdscofield]

Tires are L60 -15  rear
F60-15 front

[dual fours]

this one?  http://www.hotrod.com/how-to/engine/ccrp-1207-chrysler-b-series-400-hemi-power-at-half-the-cost/

[jdscofield]

Yes, that one

[Challenger340]

If you are bound and determined to make changes looking for a power upgrade on your 400, I would strongly suggest pulling a cylinder head to verify just what you are working with in a Piston(actual C.R.), prior to any decisions and parts purchases.

Planning, is far more important than just reading a bunch of "propaganda" in a magazine, bolting stuff together and expecting "results"?

For example:
Here is a 383 bored .030" over we did as a Performance Engine Machine Shop for a customer a few years ago.

This is a BONE STOCK aftermarket rebuilder kit using stock cast pistons, Valves, Gaskets, etc.
Upgrades were as follows:
ARP Rod Bolts
H.V. Oil Pump
Comp 274H Cam
Johnson Hylift Lifters
Torker 383 Intake W/750 cfm Holley
Ductile Iron Rockers & Pushrods.

Labor:
Block and Head Milling to "set" C.R. @ 9.2:1
Bowl Port & Intake match on the stock cast iron heads(using STOCK 2.08"/1.74"Valves)

From the above, you should gather that we have easily "equalled", or even "bettered" the magazine articles output results, given
* they used a larger 400 vrs our 383
* They used new SS radius Valves(see article pics)
* they used a larger Thumpr Cam than our "274"

Does this mean our Engine Shop should do a magazine article ? Absolutely NOT !
What it does mean, and the point of my being here.... is that good power is attainable through knowledge and planning with ANY engine...
IMO,
..... slow down, and verify your STARTING point, BEFORE you move forward.
It's real easy to just go buy stuff, much harder to know beforehand how it will work. Don't "assume" anything.

Get a Head off and measure how far down the Piston is at TDC, it is very important.