Some stage 6 stuff

This will be another one of those threads where there is only about 5 people who are all that interested....... But again, it's winter...... So I'm doing my part in providing "content".

This is sort of a continuation of another thread from about a year ago:
https://board.moparts.org/ubbthreads/ubbthreads.php/topics/2205545/1/mopar-stage-6-heads.html

These particular heads are a bit of a mystery.
They had about 10 shipping labels on the boxes, so they have definitely changed hands a few times.
They already had some cnc porting done, but I don't think it was done through MP channels.
These heads had a few ex seats that had been replaced, most likely as a means to correct some of the typical fairly substantial valve seat depth variation.
They also had 11/32 guides installed, but the ID's were unfinished and you couldn't even begin to slide a valve in.
The cnc porting ran over the guides, so they were installed prior to the porting.
After fitting the guides, the valve seat concentricity was pretty far off, so I think the previous "valve job" was done when the 3/8" guides were still in the heads.

Some of the other highlights are, the chambers are really quite large in diameter......so much so that they will require the use of a Cometic 4.600 bore gasket if you don't want the gasket fire ring hanging into the chamber.
The spark plug holes were cut too deep, and/or the chambers are cut too much, so the plugs hang way into the chambers. Plug washers can correct this.
I don't like it when the two small coolant holes by the dowels are so close to the chambers, so I plugged them.
The rocker shaft holes on one head had a raised burr around every hole, which was more pronounced than it looks in the pic, which could have created a place for oil to leak out instead of going where it needed to.

I wouldn't call the cnc work really "finished"....... But rather, more of a roughing job that resulted in a lot less time needing to be spent porting out material that shouldn't have been there in the first place.

A few more "before" pics:

Good luck with those! Looks like various people have tried to salvage them over the years but everyone to date has given up.

Since the guides were unfinished, and the seats weren't concentric to the guides, fitting the guides and recutting the seats would represent the absolute minimum work required to be able to run the heads.
Even though some ex seats had been replaced, the valve depth variation still wasnt great.
I got all the intake and exhaust seats on each head close to each other, but the two heads still had a variance of about .010-.015 between the two heads, which I planned on getting closer with milling later on.
After cutting the seats, the heads measured 92cc for one head, 94cc for the other.
These are going on a Mopar crate motor, and the part number for the service replacement head for those is 90cc, so no problem getting them into "spec" as far as chamber volume goes.
The cnc work on the intake port was fine. It got most of the big stuff out of the way, and left a little bit to work with and get into the final desired shape.
The exhaust however was not how I would have gone about it.
Way too much material removed from the short turn and floor, and too much left on the backside of the bowl.
I was pretty sure this lower ex port floor wasnt going to end up all that good...... But it is what it is.

Flow with as rec'd cnc work and seats cut, no additional porting-
4.375 bore, 28" test pressure, no tube on ex:

Lift------in/ex
.100---70.2/55.3
.200--133.6/112.7
.300--196.8/147.6
.400--248.7/165.1
.500--286.8/178.1
.550--293.5/183.0
.600--292.4/189.1
.650--291.7/192.7
.700--291.7/195.6

One of the first things I did was to plug those small coolant holes.

I tap them with a fine tap....... Then take a piece of 3/8 aluminum rod, turn it down to 5/16 so I can thread it up about 3/8" or so, then with green loctite on it, thread it into the head until it bottoms out at the end of the threads. Snug it up tight, then cut it off.

Of course since I own and run stg 6 heads on my 451 ci engine(now my spare) count me as an interested party!

Excellent tech info Dwayne. Thanks.

Don

Stage 6 heads of this vintage, which have pushrod tunnels for the intake pushrods, don't have the alignment of all the tunnels very even, and as a result, they often have a few holes that will need relieving...... Especially if 1.6 or higher ratio rockers will be used....... As was the case for these(the motor they're going on has Crane 1.6's).
So, I did some clearancing...... Hopefully it ends up being enough.

I also trimmed off that raised lip around the rocker shaft bolt holes.

Every set of stage 6's I've done have had some sort of issue that I hadn't seen with them before, and even though as a whole these weren't all that bad(in the grand scheme of things in the stage 6 world), they didn't disappoint in that regard.
I thought I had a good before/after pic of this, but I apparently didn't take an "after" pic.

I'm not sure why these ended up this way, and it's not really that big of a deal...... But something I hadn't run into before.

The massively deep spring pockets, which get modified for better drainage so the tops of the seals aren't submerged in oil, aren't a "normal" size.
They're too big to properly locate a 1.550 type spring if you only wanted to run a shim under the spring, but they aren't big enough to fit a spring cup.
And the guides don't stick out of the top enough to run a spring seat and still get full engagement of the seals.
So, they need to be opened up to use a normal spring cup.

On this set of heads, the spring pockets were no where near centered on the guides.
On some of the holes, it was cutting about .060 out of one side, and not even touching the other side.

The one before pic I have, you can see how one side of the spring pocket wall is much thicker than the other.
After recutting, they were much closer in thickness all the way around.

So, after the guides were honed, seats cut, pushrod tunnels relieved, spring pockets cut for spring cups, and modified for better oil drain back, coolant holes plugged, thread chase all bolt holes...... As well as checking to make sure there were no issues with intake manifold face alignment, or rocker shaft to valve spacing......... It was finally time to start in on improving the flow.
Nothing really too drastic was planned....... Just a basic cleanup and detailing of what was there.
A better final approach into the intake bowl along with trimming the guide boss a bit more, then knocking down the fairly course cnc ridges.

The exhaust also got the basic clean up work, but there wasnt much I could really do about the missing material from the floor and short turn.
The flow was steady on the exhaust, but pretty noisy.

Some before n after:

It would be interesting to know how much money has been spent on that set of heads over the years. Looks like the heads went to a few different shops for work but never got finished and now you are finishing them.

That picture of the exhaust port certainly violates the 85% rule!! Damn those things are big.

That's an illusion from the camera....... They really aren't that big.
I just cleaned up/squared up the cnc job, I didn't make it any "bigger".

It's well within a typical 2" header flange.

After I get the porting done, I'm giving them another little inspection and notice there is a gap under one of the intake seats.
Since its not uncommon for stage 6's to have the seats move around, or fall out, I figured it would be best to not chance it, and replaced it so I'd know it had adequate press fit.

These are supposed to be going on a MP 575hp(?) crate motor that already has stage 6's on it.
Those come with the 509 cam and he's running 1.6 rockers, and doesn't plan on changing the cam.
He also didn't want to have any intake fitment issues or replace the pushrods if possible.
As such, the heads were only milled enough to equalize the chamber volumes between the two heads, and get them under the 90cc spec....... I went for 88cc's.
I used the same springs that come on a set of Edelbrock RPM heads and set them up at about 145lbs on the seat....... Along with Comp Cams 10 degree retainers and locks.
Metal jacket Viton seals, spring cups, and SI 2.14/1.81 stainless valves.

Finished flow numbers:

Lift-------in/ex----ex w-2" tube
.100---71.3/61.5
.200--149.2/115.9
.300--211.2/157.8
.400--267.4/179.3
.500--306.7/193.2---221.1
.550--319.7/199.3---226.8
.600--318.6/205.4---236.2
.650--320.5/209.8---241.9
.700--321.6/213.9---248.3

If you look at the last pic, you can see that after milling the coolant hole plugs pretty much disappear.

As far as stage 6's go, these weren't that bad at all to do. They usually kinda need the guides replaced right ootb, the seat depth variation is usually around .060, with the chamber depths(and volumes) varying about the same amount, and when they have the monster sized guide bosses they require a fair amount of extra time in porting.

The date on the box for these was 12/96, so it took 21 years for them to be finished and ready to be used.

Very nice work!

Cool thread!

I was perusing ebay the other day and saw this:

B1 Head Package

I was thinking that the winner of the auction will be in contact with Mr. Porter lol.

B1's that flow 370?

Did you pressure test them before and after?

I didn't.

There isn't what I would call "extensive" porting.

I haven't seen leaking castings as an issue with stage 6's in general, other than the porous early ones...... But those actually look a little different, so they're easy to spot.

I've seen these damn things be porous in the bowls with no porting! Might have been super old castings but I could not believe it!

The earliest ones were pretty famous for porosity.

The ones I've worked on of this vintage often have plenty of issues...... But that hasn't been one I've come across...... Yet.

Very nice work. Thanks for the post.

I guess I don't understand why these weren't recycled into 1,000 Miller Lite cans long ago due to the other head choices we have now?!

Amazing work

look great, and looks like it was alot of work.

Nice work!!

Remember when those heads first came out and I wanted some. Saw a set up at summit on a motor and was so disappointed on how they looked port wise, especially the exhaust ports. The valve guides were so huge and port clogging.

They were definitely not designed for a bolt on app, lots of work was needed to make them work great as shown.

Winter project Dwayne.

Thanks for the post Dwayne! Your work looks awesome as always. I love seeing these posts even if it's something that I will never have to worry with (hopefully).

Very informative. I have a friend that runs these type heads. He's running 6.teens in the 1/8 so they can make power. I'm trying to get him to go B1 because he wants to go faster and I don't think he has much left in these heads. His flow about 310 per Muscle Motors.

Thanks Dwayne

Thanks Fast, I'd never own a set, but interesting post on them

Dwayne is the best!! no detail goes missed. He straightened out my old stage 6s years ago.

When I saw the subject of this t read, I didn't know if I should or and watch the story unfold.

If the owner is using the MP Stage VI RB 4150 intake manifold, he needs to look into getting it reworked to really see the benefits of the improved heads. Out of the box, it leaves a LOT to be desired.

Brad......refresh my memory.

Doesn’t the stage 6 manifold really have MW sized runners, and is shrunk down where it bolts to the heads?

That’s how I remember it.......but I haven’t looked at one in several years.

If that’s how it really is, and one was looking for the “next step” in improving the flow into the motor........I would think opening it up, and then making the heads MW size to match would make the most sense.
I think you’d probably have to make a step up from the 509 cam to really see much benefit though.

Right, MW-sized runner entries squeezed down to even smaller exits than standard ports as cast... and a sh!tty transition from below the carb mounting pad into the roofs of the ports.

The owner -- IMO -- needs to rethink the build while it's still apart to make the combination "happy". But, it ain't my car, nor my $$$.

FWIW, Dwayne's last test on my old hand-ported Stage VIs:

Stage VI test #1 cylinder:
Lift -- Int / Exh (no tube)
.100 --- 69 / 53
.200 -- 143 / 108
.300 -- 213 / 146
.400 -- 262 / 181
.500 -- 293 / 211
.550 -- 305 / 222
.600 -- 307 / 231
.650 -- 307 / 237
.700 -- 307 / 243

And these were good enough for 600+ HP on a pump-gas 440 w/ the right combination of parts. However, the subject heads are going on something quite a bit different, from the sound of things.