I have been reading and saving posts that I find whilst searching the slant sites, I have some questions.

I am also hoping I can get some of you more knowledgeable on the subject to chime in with opinions/observations.

I will try and keep identical threads on this site and the A-bodies site as I know some of you do not visit the others sites and Id like all the opinions I can get.

Original poster asked..........'Im in the process of porting a 1980 p/u cylinder head. I was wondering what to do with the small emissions breather holes in each exhaust bowl.
Is there an epoxy that will withstand the temp. or is this mod unecessary?

Doc answered..........You can just grind down the tops of the air injection ports and then plug the main feed hole at the rear of the head. (tap it for a pipe plug or use the air tube flange and flatten / weld the tube closed) ..............

Here is a piss poor picture of that air injection hole on my own head, my camera is not the latest and greatest.

I plan to do as mentioned and grind away the top portion or the area where the casting is raised to eliminate that hump.

I am a little concerned that by doing so I will making the hole that is there larger and more pronounced.

Am I being overcautious?

Yes.
A 'dead-end" hole in that location has little to no impact on what we need to do on the exhaust side of a SL6 head.

The porting "goals" on the SL6 exhaust side is to have smooth flow out of the chamber, across the valve seat and into the port "pocket".

The flow is pretty good once the "fire" is past the valve head and in the pocket area / exhaust port.
You do want to "round-off" the sharp edges, especially around the valve guide, so you can minimize turbulance as the gases transition from the pocket area and into the port "runner".
As for the exhaust pocket inself... having some open volume, right under the valve seat, simply gives the "fire" a place to go and that little EGR "hole" and the indentation it sits in, helps create additional pocket volume.
DD

Thank-you Doc, more questions to come, getting late now.

I appreciate your taking the time.

I used a late model "447" head that has the ports as you have pictured on my last hi-comp engine, I just plugged the port at the back of the head and called it good...After some bowl work there wasn't enough meat in those holes to tap and install a threaded plug, and if it came loose I didn't want it falling into the chamber on an engine with a deck height in the .0x area.

With headers and the 4 barrels, it never skipped a beat (until the clutch started to die...and I threw the fan belt...but those weren't exhaust related...LOL)...

On "torque" and street porting, as Doc noted smooth out the sharp edges, take some of the restriction out of the ports, but don't go too overboard as you want to keep port velocity up...you don't have to polish the intake ports since you want something to break up the excess fuel that tends to ride the port walls. Do only minimal work to the floor (remove casting flash, don't reduce). Make sure to have a good large compressor and/or reserve tank and get an assortment of carbides from your local tool store (Long and short shank, I use balls, flames, and cylinder with the rounded tip for best bet). A fistful of modelling clay can sometimes be used around the areas you don't want to 'booger" up if you slip (valve seat area and milled surfaces are a good place to protect).

-D.Idiot

Thanks very much Duster.

One of the questions that I was going to post here was if any of you guys had a way of helping me with terms like FLOOR, CEILING, Bowl, Most of the in port grinding is done on the bump in the floor.

Its difficult to understand what needs to be done if I cant figure out what part of the head is being referred to.

I was hoping someone here could take the image of one of the cut-aways and use a program like paint ( that the one I have and the only one I know of ) and add some text with arrows showing where are these different areas were.

Maybe also where exactly the areas are that can be cleaned up/hogged out a bit.

I would be willing to pay someone for their time and experience.

Can anyone help with this?

[quote]FLOOR, CEILING,[/quote]

Look into head’s passageways the intake manifold butts up to called a Runner. Top of the rectangular opening would be its ceiling, bottom surface its floor…


[quote]Bowl[/quote]


It’s the rounded spherical space at end of runner and back side (stem side) of valve where valve stem passes through into its guide.

What one needs to do is just remove and smooth all casting warts and imperfections from these internals surfaces, and any sharp edges so air/fuel mixture and flow more smoothly over these surfaces.


Gasket matching:
This is where one smooth’s or ramps or aligns the surfaces between manifold and head so there is no place to stub one's toe so to speak as air fuel mixture passes along the two different runners.

All we are trying to do is get the air/fuel mixture to flow along the runners as smoothly as possible without removing too much metal and braking into water jacket which would turn the head into 80 lbs of scrap iron.

Another step in getting these heads to flow better is to install oversized valves.

Several years ago I ported and installed oversized valves in a shaved head. The first time I started the engine put her in “Râ€￾ backed out of the garage after all that work I could tell the engine was developing more power; it was that noticeable.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

My 2 cents:

One has to realize the slant six head was designed for the 170 ci than used unchanged on the 225 cid engine so it really needs some work to flow proportionately as a 170 in relation to displacement. I probably didn’t say that very well, so let’s just say the head need help to flow better on the bigger engine. You can easily improve flow into the back side of intake valve with aftermarket intake and larger carburetor, and from the back side of exhaust valve to the rear bumper is easy to make a better flow with headers or Dutra Duels and bigger diameter exhaust pipe. BUT---- if the valve size and its lift and duration are not increased a bottle neck persists limiting flow into and out of the combustion chamber; so oversized valves that open a little higher and longer help a poorly designed head to flow more air & fuel to the spark plug.

If you are going to invest in aftermarket cam, larger carb, intake manifold, and some sort of oversized exhaust why wouldn’t one finish the job with more compression, and oversized valves? You don’t have to build a mad-dog uppity high strung race engine to get a noticeable increase in performance in every day driving.

My car with 3.55:1 rear end runs the eighth mile in 10.3 seconds at 68.3 mph turning just under 5K rpm, and it never gets out of second gear doing it. Engine will easily turn up to 6000 rpm. On line calculator converts to a ¼ mi time of 16.06 sec. Not too bad for a fully dressed convertible with a 225 pounder at the wheel.


Others may have a different take on this...

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Yes alot of different opinion. What size valves are you running and where did you purchase? I have read many posts that mention engine builder valves and Ford 300 valves.

To be more accurate I have read about

Engine builder valves....no idea on what sizes are avail

*ford 300 six valves......doing an on-line search I am still not sure of these valve sizes, evidently there is a large and small

*BB mopar valves

*The common 1.70/1.44 valves

Apparently the first two choices above would possibly require some chamber work.........but I have also read that the Ford 300 valves are avail in two different sizes and the smaller one may not require chamber work.

Too be honest Im thinking that the since the stock valve size is 1.62 Intake and 1.36 Exhaust that stepping up to the 1.70/1.44 valves might be just fine and dandy for what I am after.

Have no idea where I can purchase them at this point and am thinking these might be the Mopar Performance valves offered at one point years ago that are now discontinued and made from un-obtanium but please correct me if I am wrong.

I am also reading about back-cut valves. Not sure what the means....backcutting a stock valve? I havent gotten this far yet to figure out what this is referring to.

I would like your opinion on these valve sizes. I am not trying to go the cheapest route by any means. Money isnt my biggest issue as this is a long term project, just trying to use common sense when looking at the big picture for what I am trying to do/where Id like to be.


I wish I had the option of removing my freshly re-built engine so that I could disassemble and hang the head on so that I could see how the combustion chambers lined up with the cylinder bores.

I cannot justify doing that at this point though cause I worked to hard at assembling the truck and then spraying it so that all the underhood nuts and bolts were pretty and I dont want to ruin that just yet.

Do you go with a standard 3 angle valve job?

Duster I am a complete novice at this sort of thing, I am reading and having to re-read posts but am slowly getting it.

You said in your post above ...........Do only minimal work to the floor ..........This has me a bit confused.

From other people posts the orientation seems to be that the head is described as if we were looking at it installed.

In other words if we were looking at the rectangular hole all the way back at the intake we would call the ceiling the area at the top of the rectangular hole and that extends into what is called the bowl area.

The floor as you mentioned above would actually be the bottom and I see no way doing any work to this area at all unless I am missing something.

Am I confused or is there just a difference of opinion of description.

BTW why do you describe the head as a 447 head. What does that mean? How do I tell what sort of head I have?

Thank-you again for your time.

I have read this being mentioned quite a few times..........A reminder to everyone on the OS valves. Dont let your machine shop get lazy and sink the valves into the head. Just enough for a good seat no more. .................


I dont get it, why would the machine shop sink the valves down in further? Wouldnt that in itself cause a shrouding problem if I am using the term correctly!

1930:
[quote]Yes alot of different opinion. What size valves are you running and where did you purchase? I have read many posts that mention engine builder valves and Ford 300 valves.[/quote]


I used Engine Builder Valves; they have correct stem dia & length, are back cut, and a lot of the folks use them; one size E = 1.44â€￾ & I = 1.70â€￾. Ford 300 valve needs more machine work to fit head, and 0.060 over bore; I suspect more suited for full race builds and big over bores.


[quote]Too be honest Im thinking that the since the stock valve size is 1.62 Intake and 1.36 Exhaust that stepping up to the 1.70/1.44 valves might be just fine and dandy for what I am after.[/quote]


If you can take the time to calculate the opening gross areas (space between edge valve & seat and circumference at full lift) between stock valve and Engine Builder valve one will find a nice percentage in increase in area when using same cam. This number is dependent on lift of cam, and if you were to increase lift, well the area gets larger.


[quote]Have no idea where I can purchase them at this point and am thinking these might be the Mopar Performance valves offered at one point years ago that are now discontinued and made from un-obtanium but please correct me if I am wrong.[/quote]


[url=http://www.enginepartsnetwork.com/valves.html]Non un-obtanium found here[/url], as well as springs, and lockers

Yup the above are back cut. All that means is at the back side of valve head the stem has a nice radius transition to a reduced diameter valve stem to help gasses and air/fuel pass by it more smoothly within the bowl area.


[quote]I would like your opinion on these valve sizes. I am not trying to go the cheapest route by any means. Money isnt my biggest issue as this is a long term project, just trying to use common sense when looking at the big picture for what I am trying to do/where Id like to be.[/quote]


I used them after following the advice of others on this site that have been building heads & racing for a long time. E. B. valves are high quality, and I haven’t heard anything negative about them since joining this site, there are a goodly number of folks out there using them. Others may want to chime in these valves.


Ahh, shoud’ah, could’ah mission creep; something I and many others suffer from here. I would just trust the head and block mating to be sufficient. My engine has a 0.030â€￾ over bore, and ground a relief around the side of head closest to intake valve to keep the flow moving. Check the porting articles under engine stickies.


[quote]Do you go with a standard 3 angle valve job?[/quote]

I did, as well as new hardened exhaust seats because the enlarging of holes to accept the new larger valve will often remove the factory hardness and my Machinest took the time to smooth up & blend the back side of the new seat into the bowl surface. This wasn’t his first performance build on a six, and he was onboard to build a nice running perky engine.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Why does anyone cut corners?

laziness, lackadaisical attitude, lack of understanding of a performance build, it ain’t a Chevy, this is a six who cares; what difference does it make…

Yes more shrouding right out of the box and more importantly an increase combustion chamber volume, possibly making combustion chambers unequal volumes all which will throw off your calculations for compression targets, and cause uneven cylinder pressures.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Mopar enthusiasts describe the car part by the last 3 digits of the part number...so if you had a set of famous 440 Commando heads from 1967 they would be a set of 915's....by 1975-1976 mopar went to the BL plug head in the slant six and there were two versions: the non smog port head (the "600"...kind of rare to find...I have one), and the others with the hole at the back of the head for the smog pump or charge tube was the "447" head...if you have a post 1981 it will have a different casting number, but the ports are still in the same spot and it will perform the same as the older 447 head.

Yes, that is the short curved stretch of the port that is on the bottom if the head is installed...and yes, you can get in there from the intake mating surface, and with a long shank die from the valve bowl...there are just not any gains to be made here, although if you gasket match the ports you may find this part to be up to an 1/8" out of tolerence to the intake depending on the casting quality that day at the mopar foundry...if that's the case, just smooth it so it forms a gentle ramp.


-D.Idiot

DI:

Me too. Never knew it was a scarce item. Was it a one year only design?

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC