Best Performance Heads for 340???

[Chryco Psycho]

the 308 is used on 360 trucks , they use the smaller 1.92 intake & 1.65 exhaust & have a reworked port for more velocity & swirl , you can go larger with the valve size I believe the chamber is about th e same cc as the earlier 360 heads  

[cudacody]

The reason that I ask about the chamber size is what if these heads are ported and polished will it lower the engine compression ratio as opposed to having the 340 heads ported?? Or would you notice much of a difference.
  I know that I've got lots of questions about head selection, but you guy's/gals always have the answers.  >>>Very Much Appreciated............."Tim"

Porting and polishing your heads will not change the compression on your motor.  What you need to do to get the compression that you want is buy the pistons that will deliver the compression that you are looking for.  When you go to order your pistons talk to the manufacturer about your setup and let them know what kind of heads you are going to use and they can make sure that you get the compression ratio that you want.  Either that or if you already have the pistons that you want or already have pistons in your short block then you can shave your head, to increase the compression.  Porting and polishing will just increase the amount of air/fuel mixture that you can get into the combustion chamber, and help that air travel to the combustion chamber more smoothly, which both help with the efficency of the head and help it make more power generally speaking.  If anyone would like to add to this or clear any of it up feel free, but hope this helps you some Woody.

[DodgeFreak]

And if he already has pistons and they sit below deckhight he can shave the block some and it will bump compression but then he will have to do something to the intake.......shave it?? or something to get it to match the different angle of the block.

[cudacody]

Something else you might want to consider is having your intake manifold and heads port matched.  It doesn't really matter how much your heads will flow if your intake ports are smaller than your head ports.  So if you don't already have your intake, think about getting one that has similar size ports as the heads that you want to use.   This is getting into the nitty gritty and trying to squeak everybit of power that you can out of your combo.  But if you are thinking about haveing your heads ported, possibly think about having the intake ported too.  It just goes to show you how you have to pick a combo that works together to make power.  Your cam will be a big factor in it also.  There is no use getting heads with a massive amout of flow, and then using a cam that can't take full use of all that air those heads can flow..

[Steve]

Yes, the 360 heads have larger chamber volume and will drop compression ratios, all other things  being equal. The '72 340s used 360 heads in order to drop compression.
Anybody have a good feel for max safe compression usinig Iron heads?

[cudacody]

On pump gas?  Probably somewhere in the neighborhood of 13.0 to 1.  Anything too much higher than that and you are pretty much looking at using the high octane race fuels

[Steve]

That seems a bit high, but maybe. I was thinking in the neighborhood of 9.5:1 on 93 octane and maybe 10.25:1 with aluminum heads on 93 octane. Too low?

[360 'CUDA]

I ran O-rings on the 10 second motor

(That's the old 340 pistons in the 360 trick)

With that much compression the O-rings and thick head
gaskets were the only way to go

Couldn't run the 340 heads because the 202 valves
hit the piston

[Chryco Psycho]

there are a # of factors , the amount of overlap & duration designed into the cam [this will bleed off pressure] , use of quench to resist detonaion ,  Rpm where the load is applied [it is more likely to detonate at low rpm , higher stall converters & lower gears will reduce the load]  
 Generally 9-5-10: 1 with Iron heads is max however with with 4.30 gears a 312 duration cam & quench I was able to use 11:1 with no problems , with alum heads you want 1-1.2 more compression to offset the heat loss to hte alum

[woody9512]

Mopar Performance sells the following two types of iron heads for a 340.

W-2 Heads........2.02/1.60 valves all flow about 260cfm @.600 with 185cc intake port...but the chamber size can be ordered from about 70cc down to 55cc.
>>>>Can these W-2 Heads be used on a stock 340 block or does it have to be a race block???

360 Ported Heads....2.02/1.60 valves flow at 275cfm @600 with 166cc intake port and 70cc chamber size.

Can anyone tell me what the major advantages / disadvantages are between them and which would be considered better from a performance standpoint??
Thanks.."Tim"

[Chryco Psycho]

the W2 fit a standard block , you can increase compression with the different chamber size , tthe larger intake port will flow better at higher RPM
 The 360 head has only 1 compression ratio available bu twill flow better at lower rpm due to the smaller port which gives higher veolcity  

[72hemi]

The problem with the W2 heads is that you cannot run standard intakes, exhaust manifolds or standard headers and they also require special rockers. I thought about going with the W2's but changed my mind because of all of the standard parts that cannot be used. (also even painted engine color the W2's stand out with race headers and a large single plane manifold). I suggest a good set of ported cast production heads, that seems to be the best choice that I have been finding, other than an expensive set of INDY heads.

[Chryco Psycho]

true W2s are a unique animal

[Follicly Challenged]

Some 308 Porting Techniques;

The 308 head retains the Identical chamber, and Intake port, common to all earlier "J" castings.

Noted additions from "J's" to the 308, were the introduction of a new exhaust port(with incresed short turn height), to promote better cylinder scavenging, and balance, and a "narrowing" of the entrance on the Intake port, where it passes the pushrod, by an increasing of the hole size/casting around it, to protrude into the port.(velocity/torque)

A piece of .500" copper pipe, from the plumbing store, makes a nice guide, to be inserted in this larger pushrod hole, for porting purposes, when widening the 308's port. Retain with "Titanium Putty", or, buy a Comp Cams lifter bore "broaching tool", to peen the interior of the hole for a "press fit". (more expensive)

 Remember to add volume in the port, behind the reworked open wall, proportionally, and blend through to the bowl. This allows the charge to "slow down" and make the Intake short turn, without crashing out the backside of the Valve.(Port goes "sonic" too early in the flow rate). Simply enlarging the opening, without proportional volume in the bowl, causes the charge to actually "speed up", rather than "slow down" as it makes the valve.

Do people still port Iron heads ?  No Wars wanted, just curious ?

Bob out.

[jvike]

Talking Aluminium, Does anybody have experience with the INDY-Edelbrock heads? They are $1000 more than the Edelborck Preformer RPM, I guess the Indy-Edelbrock falls between the Indy heads and the Pref.RPM both pricewice and in preformance.