Head Porting

[440Charger]

Hey guys,

I'm curious about head porting and when it's needed.  I know there are multiple levels, from mild to complete porting.  Could anyone give me an opinion on when it's needed, and how much?  In my case, my cam spec is 480/292.  I think the cam dictates the level of porting (correct me if I'm wrong).  Does valve size matter? Mine are 2.14 intake & 1.81 exhaust.

I'm currently using stock '78 440 heads (with the larger valves).  Any speaking of heads, I can't find a resource to tell me what heads I have.  They're off a '78 New Yorker 440....any ideas?

Thanks,
- Doug

[Chryco Psycho]

good ?
basically Any engine will respond to good port work , most stock size , mildly built engines do not Need a huge increase in port volume but in engines with more air flow , high RPM , strokers ETC you simply need more air flow to feed the increased demand . I n cases like your where the larger valves are used you simply have to bowl port the heads & whilel you are at it gasket match the intake & heads & open the exhuast port
 I have witnessed 41 RWHP gains on a dyno just swapping heads , no cam change or tuning on a 340
  I port the heads on every engine I build including /6s , with carefull shaping the flow around the valve guides is cleaned up dramtically & you can enhance swirl too which inncreases the overall efficiency of the engine

[Chryco Psycho]

these are big block 915 casting that I finished porting today

[Chryco Psycho]

more, the second pic shows the intake Above the the 1st below  the left one is ported the right is not
 the bottom 2 pix show the ported & unported exhaust

[440Charger]

Yeah that's an obvious difference, looks nice.  I wanted to port our heads from the git-go but the guy who helped us said it was a waste of money.  I'll probably push for the bowl porting as you suggested. 

I don't know what gasket matching is.  In regards to "open the exhaust port" are you suggesting more than 1.81 exhaust?

[Chryco Psycho]

Gasket matching is placing an intake on the head & intake manifold & opening the port to match the gasket size
opening up the exhaust is raising & widening the exhaust port tp increase exhaust flow
 I flowed a similar set of heads & the ports were ported identical to this & the flow was still increasing at .700 lift & the amazing part is no flow was lost at the low lift #s , so it increased all the way up 
 the other thing to remember with porting is that increasing flow does NOT = increased power , with bigger ports you lose response & velocity & there is a balance between more flow & velocity  this is why the Hemi runs the way it does the Huge Hemi ports lose response & as was discussed in another thread the Hemi will hunt you down in the 1/4 mile even if it is 3-4 car lenghts behind simple because it takes RPM to make the ports efficient , this also applys to after amrket ALum heads for the wedge engines , you can buy heads with HUGE ports & high flow #s But they are designed to work at 7000 rpm Not at 1500 rpm on the street , the other end of the scale is if the port is too small & the velocity is too high it will not completely fill the cylinders 

[Chryco Psycho]

78 440 Heads would be 452 castings they had industion hardened exhaust seats for unleaded fuel but with the large valve you will have cut through the hardening , these are an 88 cc open chamber head

[440Charger]

Is there a good way to find local machinists that do this kind of work?

[Chryco Psycho]

tough to find & everone has their own ideas on what is right , a lot of them over port & I have seen some that actually have damaged alum heads to the point where they flow less than if they were untouched

[440Charger]

Does anyone know of any good Minnesota shops?

[moper]

Your best bet is to tell them to "bowl blend and gasket match"...Dont let them enlarge the ports unless they have two things. A working flowbench, and experience with mopar heads. The first $250 gets more results than the last $800 in porting. To be honest, if you dont know who to use, dont bother. Any engine will respond better, but if your guy isnt good, they will take your money, show you some shiney stuff, and it wont mean much at all.

[440Charger]

CP do you usually smooth and polish the bowl/chamber for better swirl ect??

[Dave-R]

Good work CP.

Here are some photos of my 906 heads. Initial porting on these heads was done by Dave Hughes so I can't take credit for that. Although they are strikingly similar to the last pair of heads I did myself.

On these heads I have just worked around the valve reliefs a bit more (matching notches cut into the tops of the cylinders) and worked the bowls a bit more too. I smoothed the chambers into the valve seats and gave the chambers just a little smooth to help keep heat in the chamber more than anything.

I did smooth the exhaust ports more than anything else.

Notice there is very little material removed from the port runners. In particular never remove material on the short radius. You can still see casting marks there if you look closely.

[Chryco Psycho]

I smooth the roof & sides of the ports but leave the floors rough, on the intake port a rough floor will trap liquid fuel that drops out of the air stream & force it to evaporate before going into the cylinder , liquid fuel will not burn in the cylinder , on the exhaust side a rough floor will push the flow upwards making the floor seem higher which is what makes power in most aftermarket heads . I do widen the intake port by the pushrod & i measure each port to keep them equal & the exhaust port is substantially widened to make the outer wall away from the chamber virtually straight . as for the chamber I do remove any casting flash that could create hot spots & detonation & slightly polish the surface

[Dave-R]

I smooth the roof & sides of the ports but leave the floors rough, on the intake port a rough floor will trap liquid fuel that drops out of the air stream & force it to evaporate before going into the cylinder , liquid fuel will not burn in the cylinder , on the exhaust side a rough floor will push the flow upwards making the floor seem higher which is what makes power in most aftermarket heads . I do widen the intake port by the pushrod & i measure each port to keep them equal & the exhaust port is substantially widened to make the outer wall away from the chamber virtually straight . as for the chamber I do remove any casting flash that could create hot spots & detonation & slightly polish the surface

All good tips. I like that one about the rough floor on the exaust port in aftermarket heads. Is there any benifit to that in stock heads at all?

I generally take some off the pushrod area but I don't like going too big in the intake port volume as the car is 95% street driven and I worry about keeping the intake volocity up at lower rpms. Typically 3000-4000rpm is my normal driving range. Which now I have written that is not that low an rpm is it?