Porting ? for cuda66276 are anyone

[23T]

In the pic's DartGT66 posted to my 456 porting job it looks like the valave guide boss in the ex port has been lowered.

My ? is do you leave the intake boss the same hight and lower the ex boss, lower both, or leave both the same hight?

If any or lowered how much?

[Nightri1]

It is best to leave as much guide as possible for an intake valve. It needs the oil and the stability. The exhaust guide can be less but not all the way off to the roof of the port.

[6 packin]

Hey T!
Here is a port of a 516 head closed chambered that no one here likes. As you can see they open up nicely. I did not try to cut on the guide much just rolled and blended, but in the process it was shortened a little.

[23T]

Hey 6packin that is what my ports look like. first head I tried to port like the pic's I refered to in the post I got into the water jacket where it was cut down by the boss to make the ridge.

THe price of the heads not that bad, but the shipping + time makes me :flip: when I ruin a head.

If you get a chance look on page 4 post "452 P&P pic's" and tell me what you think. I'm not looking for raves on my job just ideas.
This is a mild 400 engine in a 1900# car( shooting for 400+/- HP in this engine @ 6200 RPM max)

[6 packin]

I compared the 2 pics on that post to my pic. They look good. Did you do the valve guide boss work yet? That alone opnens the bowl up more than one would think. Did you grind on the short side much? I bet thats were ya hit the water jacket. There isnt much there. The flatter the short side makes a big differance. The bowl and the short side is the main parts. Even gasket matching unless off big time wpould hardly be noticableon the street. I am hoping that with the bowls, short side work (minumal), and the opening with the gasket matching will be worth a little. But still not much maybe 30 Horses or so. Oh yea the exhaust valve in those heads are 1.88 inch and 2.14 exhaust. People on here has dogged the 516 head from day one,...........but loves the 915's.... and there the same head. The only advantage a open chamber head has is lower emissions. I dont think anyone with a 60's or 70's Mopar is worried about that.

[23T]

Have not cleaned up the boss's yet, doing that right now, did a gasket match. Your right about were I met the water. When I get through am going to the shop/ mill .60, 4 angle Manley SS 2.14/1.810 valves with 30' back cut.

If the heads give 30 hp I think the .60 heads, new cam & intake will get me in the 400+/- range.
Thanks 6packin

[Kevin Garceau]

Well I really have no idea except what I have been told by very knowledgable people.... but

They all have told me not to touch the short side radius. Yes you will open it up and will seem like it would work better because it is more area to flow......but'

you will critically kill the velocity of the head, top flowing cfm is not everything the velocity is also important.

It has been about 8 years since I had to think much about BB mopar heads but that was the thought then, who knows though lot changes. They might have been smoking crack back then and had it all backwards.

[6 packin]

The short side is were most flow occurs. When the valve starts to open the air/fuel barrels down the intake and fkows along the short side or floor of the head. If you look at a cut away of Indy or Edelbrock heads you will see the diff in the short side or floor of the runner. Thats WHY they have raised runners and exhaust opening. By raisng the other parts of the head is were the try to flatten out the short side. Alot of people may say not to touch it there, but they dont acctually know why. Yes the head can fshow no improvement and water can be had there very, very easy. Just ask me how easy, or 23 T for that matter. Its best to practice with a old junk head to see what limits you have, but due to core shift even that may not prevent turning a good head into a high dollar boat anchor. Reguardless of what people say most flow improvements will come buy way of short side mods. Think of air/fuel flowing through the head like pouring water down the intake with the valve open. The flow will have very few differances between them. The water will flow along the floor of the runner and very little if any on the roof. You can see why its important to the bowl area.

[DartGT66]

True, but it's also the point where you can do the most damage and basically ruin the head. Laying the short side back too much will really do harm, so without experience and a flow bench I would suggest being pretty moderate with it.

[cuda66273]

Yup, porting and blending of the short side on any Mopar BB head can be tricky and once you blow a hole it's a boat anchor.

This still doesn't mean it can't be done, huge gains can be had from careful work on the short turn. The problem most home porters have is they have a tendency to look at port size rather than air management through the port and valve opening, this combined with too much lift will actually make the flow go backwards.

About 4 hours per head of machine work and hand blending will get you about 75% of all the gains you'll see in a BB head, the other 25% comes at 4 hours per port and high risk to the casting.

$1000.00 will usually get you the full meal deal, supersized with Biggie ports, 11/32 stems, big valves, polished out chambers, ported, gasket matched, surfaced and cut for compression, cc'd ports and combustion chambers, a Comp valve job, all parts, assembly and a coat of black Krylon.

It also includes a recommended cam profile based on car specs, flow curve, compression ratio, carburetor and intake.

Extras would be Titanium retainers and valves, SP springs, valve massaging, thread repairs, spark plug hole repair and excessive chamber and port balancing to exact cc's.

A balanced package with good parts and top notch workmanship.

This is a head program designed for Hot Street and Bracket Racers wanting to run in the high ten's low elevens.

[6 packin]

Man...........That sounds so sweet............ If only I had more $$$............


.........Do I get fries with that?

[cuda66273]

Start saving your allowance up, you'll have it in no time...

Sure I'll throw in some fries...did you want ketchup and salt?

[sundrop_440]

say I got a question for 6 packin or 23t I heard that the 516's have smaller ports than the 915's and thats why they supposedly flow less I 've got a chance at a pair locally for 100 bucks I really want that closed chamber for the comp increase and sqeese .I have those trw 2266 pistons and I'm going to port whatever I get but I'm just not quite sure which way to go 906,452 and mill a bunch or 516 and mill alittle

[6 packin]

Is the runners smaller? Well, yes and no! The have smaller exhaust valves compared to the later heads. 1.6 vs 1.74 The area under the valve (bowl) is smaller also. just cutting and installing the bigger valve is no help also. The bowl must be opened up at least 75-80% of the valve. Or they will be a bottle neck effect. It would not matter iif you had a 2 inch valve there if the port and bowl will not substain the extra flow it is pointless. The runners are all almost identical from about 67 to the last years of production. Very little differance. I would not stop there though. Blend in the guide boss and flatten out the dog leg turn and the valve guide boss hump will help alot. Do a good port match on them to the intake. Those heads can be made to out flow any of the stock 452's and 906's very easy. Fact is factory BB Mopar heads (excluding Hemi) are not that great of design Compared to Chebby and Ford BB heads. But as said many times before hogged out ports are not always the answer and bigger is not always better. Flow velocity is the key to making good torque which has made the Big Mopars what they are today. But simple mods like that can really take advantage of cams with .500 inch and higher lift cams. These heads can be made to flow around 300 cfm if done right. Also note 1 advantage of the open heads I never thought about is that the closed heads tend to shroud the valves for flow. This holds more water for heads with over size valves like 2.14 & 1.81 Since I posted my pics I have polished the chambers and done some minor deshroud work in the chamber area. Its Important here and with any port work is to remove the same amount of metal in the same places. Thats why the need CC'd. You can mill of what chamber volume is lost fairly easy. I have all my heads deck just for squarness and cleanup any way. It doesny cost more to have them take of a extra .020 inch.

Good luck

[cuda66273]

Well said 6Packin'.....we take a plunge cut on the combustion chamber side of the valve to open the area up and allow for the air to get into the chamber with as little disturbance as possible.
Like you said, whatever is lost in the chamber rework can be brought back with a surface cut to maintain desired Compression ratio.

Don't discount the 516 casting, with the right piston you can make big compression numbers and control the flow to .550 lift with pretty basic port, chamber and valve work...300 flow....that's possible but a tough goal, I would say 260-270 numbers are more achievable unless you want to spend big $$$ on excessive port work and flow bench time. Also note that the management of the air and quality of the burn are even more important than huge flow numbers.

Jim McFarland, the Performance Professor wrote an excellent paper on this subject after doing extensive research, I'll give him a call and see if I can get a copy of that article and permission to post it here.

[6 packin]

I would love to read that man! Post it if you can.
Thanks Cuda66273!

[DartGT66]

Here is a short comparation of the potential of the different castings by Dwayne Porter: http://www.moparts.com/ub/ubb/Forum4/HTML/000054.html

[cuda66273]

Excellent post...well researched..and alot of work!

Now you can see all the the time involved in a race port job on iron heads.

32 hours plus another 6 hours to polish the combustion chambers..38 x $50 hr=$1900.00 now we do a valve job, guides, machine for posi seals,surface and assemble.....Now you've got $2500 in them.(If you can find a machine shop to work for $50/Hr.)

We've found that a basic bowl hog and blend with some time spent on the short turn produces numbers in the 260-270 range on the 906 at 550 lift for less than 1/2 the time and money, it really depends on how much you want out of the cast heads and at $2500 are you better to go with a Indy SR with the CnC port job?....I believe they run about the same dollars.

[23T]

Don,

All of the cost factors you stated are true, but when you do the P&P youself you get more, you get to buy lots on new tools, learn new curse words, stay on line asking DA ? like me, have a life time supply of boat anchors and if you do the P&P on the kitchen table you get to look for a new cook. LOL

[cuda66273]

New cook!!...hell No!! it took me 30 years, 4 wives, 9 live-in lousey cooks, 3 houses and a perfectly good Pick-up to find the one I got...of course with a name like Holley and a .540 RT at the lights how could I not love her.....LOL

I'll keep the port work out in the shop...