Home porting a set of 516 heads ?

[Brandy]

Opening up the runners and smoothing the pinch is a good way to gain HP and flow.

 

[PRHeads]

Some ex work:
I- grind seat
J- rough in bowl and guide
K- sand roll finish bowl and guide

 

[Jcharger]

Amazing work. Appreciate the posts and information.

 

[BSB67]

Thanks Dwayne.

A few questions. For discussion, lets use the up to 0.500" lift numbers for reference. For for all of the gain in "A" over stock, how much is attributed to the high quality competition valve grind and valve back cut verses how much due to the porting. I understand it's not linear (low lift gains from grind/valve, high lift gains from porting) but if you could estimate the overall percent gain from one verses the other up to the 0.50" numbers.

Then again between "A" and "B". How much from the port window opening verses opening the pinch?

 

[PRHeads]

L- port exit as cast
M- port exit opened up to the size of metal gasket that’s used with ex manifolds, and blended into the work done on bowl side.

Test C- valve job, guide boss, bowl.
Test D- add ex port opening work

Tested with a 1.74 OE valve with back cut, 4.375 bore, 28” test pressure, no tube

Stock heads flow mid-150’s

Lift——C/D
.100— 56.1/56.1
.200—103.7/106.1
.300—137.1/140.8
.350—151.2/156.6
.400—162.7/170.0
.450—170.8/178.6
.500—177.3/185.4
.550—182.2/189.1
.600—185.4/193.2

 

[PRHeads]

Russ, for the most part(in this type of application, with this type of head) the valve job affects mostly up to about .200-.250 lift, from there on up I’d say 90%+ of the gains are from the porting.

On the port entrance side of the intake....... the gains are probably at least 95% the pinch and smoothing that curved wall.

The as cast openings aren’t very uniform, so if you make them all the same size, you eliminate that variable.

A later casting(346,902,452) head that flows over 225@.500 lift with nothing but valve and seat work(zero porting) is a pretty rare thing(and I’ve never seen one break 230).

But, a nice valve job, back cut, and a very good use of 4 minutes with a carbide can get you over 240+.

 

[PRHeads]

Let’s be clear, I have what I would say is an above average amount of experience working these old stock iron heads.
What I’ve found, with the mildly reworked efforts in particular, is that I get more flow out of this type of job than heads done by several other sources, that have had a similar amount of work done to them.
Based on what I’ve seen come into my shop and onto my flow bench.

As an example, I just recently had a set of 452’s on my bench that were done by an experienced Mopar shop.
These have what I would call a “basic full port and polish”. The entire port has been reworked and sand rolled, along with the chambers, which have also been relieved adjacent to the 2.14/1.81 valves.
They flowed:
Lift—— in/ex
.100— 67.5/56.7
.200—142.8/111.0
.300—207.6/150.0
.350— x x x/x x x
.400—241.2/167.1
.450—252.4/170.0
.500—256.1/170.8
.550—256.9/173.2
.600—260.6/174.4

The intake flow is very similar to my 346 test head, but this 452 had more porting, and the bigger valve.
The ex port actually flows less than the 346 test head with the small valve and only a nice bowl port.
If I added a 1.81 valve to the finished 346 test head ex port, and relieved the chamber adjacent to the valve like the 452 is, it would easily be over 200cfm.

Looking through my notes, if I did an “equivalent” job to what was done to these 452 heads, the flow @.600 is more like 270-275 on the intake, and 200-210 on the exhaust with the 2.14/1.81 valves.

 

[PRHeads]

I realize not everyone lives close enough to a machine shop with a flow bench, or even one that has a decent reputation for their porting services to make it feasible ....... but....... if you do, and you’re serious about making a noticeable improvement in the performance of the motor(instead of just hap hazardly doing some grinding on the heads to say you did something), I suggest you bring three heads to that shop.
Have the two “good” heads cleaned and prepped. Make sure the guides aren’t all worn out, and have the valves and seats touched up.
The third head, which doesn’t necessarily have to be the same casting number, have it cleaned as well.
Have the shop port one cylinder on the third head to the level of work you’re going to try and replicate.
If you’ve never done this type of work before, have the shop do a pretty conservative job.
Now you have three more cylinders on the third head to practice on, trying to replicate what the shop did, and get a feel for working with the porting tools and honing your technique.
Then, when you’re more comfortable using the tools, start in on the two “good” heads.
If you’re not quite ready after doing the 3 cyls on the test head, or don’t feel you’ve done a good enough job of duplicating what the shop did....... get another head and keep practicing until you’re ready.

If you’ve never done this type of work before, you’d be surprised at how much better your work is after several hours of practice(if you have any real aptitude for it) than what it looked like during that first hour.

 

[PRHeads]

A few more numbers...... from heads supposedly done by shops who were “good”.
I say supposedly since there wasn’t first hand knowledge that who I was told did the work, actually did the work.
These are both 906 heads, both are “fully ported”, meaning the entire port had some degree of work done to it.
And, they didn’t look too bad either.
Both were to be used with 440 based strokers, where the owners were hoping to make some pretty good power.

Test 1 is a head with an unknown brand 2.125”, 11/32”stem valve

Test 2 is a head with a Ferrea 2.14”, 3/8” stem valve.

Lift—— 1/2
.100— 65.4/65.4
.200—133.7/133.8
.300—200.5/198.0
.400—242.6/238.1
.450—253.4/230.4
.500—252.2/236.2
.550—250.3/240.8
.600—238.0/240.0

Both of these examples seemed to follow the direction of the MP engine book/porting templates of not reworking the short side radius...... and the results kinda speak for themselves.

 

[PRHeads]

To add a little perspective to the previous numbers...... I have some new Stealths in the shop at the moment.
Here are some ootb numbers......
4.375” bore, 28” test pressure, radius plate air entry

Lift——in/ex
.100— 67.2/51.2
.200—144.0/102.4
.300—207.6/135.4
.350—230.0/148.8
.400—244.9/159.0
.450—256.1/168.3
.500—259.9/174.4
.550—261.8/178.6
.600—258.0/183.0

 

[Brandy]

To add a little perspective to the previous numbers...... I have some new Stealths in the shop at the moment.
Here are some ootb numbers......
4.375” bore, 28” test pressure, radius plate air entry

Lift——in/ex
.100— 67.2/51.2
.200—144.0/102.4
.300—207.6/135.4
.350—230.0/148.8
.400—244.9/159.0
.450—256.1/168.3
.500—259.9/174.4
.550—261.8/178.6
.600—258.0/183.0

View attachment 711273

Why does it make any difference who did the supposed work? Are you not in the business of testing heads, and or porting ect? They either flow or they don't, and you either get the job correcting them, if possible, or not. What difference does it make who worked on them? Just curious. in an earlier post you mentioned something about owners doing their own work ,
(instead of just hap hazardly doing some grinding on the heads to say you did something), which struck me as an odd thing to say when your wanting owners to give you work. It almost seems like your on a campaign to disparage all other shops, and or owners who do their own work.

 

[PRHeads]

You can take it how you want.

My point was that getting fairly substantial improvements out of these heads requires you go about it a certain way, and that just grinding on them and making them pretty doesn’t necessarily equate to big improvements.
And, that sometimes even shops with good reputations, who have charged a premium price to the customer for the work performed, may not be providing the kinds of gains that were anticipated.
That’s why I think it’s worth noting who did the job.......a “shop” or a DIY.

If it’s a DIY job and the owner gets the heads to 240+cfm for a few dollars worth of tools and some elbow grease..... that’s great.
If he just spent $800 in porting and ended up with heads that flow less than 250...... not so great.

My point is....... work smarter, not harder.
Port where it matters.

I like getting the most flow for the least amount of work.

I posted the pics to give a visual aid as to what I did, and posted the flow numbers to show how that work performed.
The comparisons with the other heads are to show that what I did was pretty effective, even when compared to other heads that have had more time and effort spent on them.

And, I specifically don’t mention any names or shops as to not disparage anyone.

For a positive reference of another shop........ the best flowing 906’s I’ve had in my shop were the CNC ported offerings from Muscle Motors that had 2.19”, 11/32” stem valves installed.
MCH also has a very effective CNC program for 906’s.

 

[Brandy]

Hmm...I see what your saying. Well. I don't know what other DIY guys have done but personally I read everything I could and watched everything I could and practiced on a set of 452's for a week. While I am in no way experienced at it I feel I did a decent job. At least I feel I didn't make them worse anyway. I don't intend to race this set up, and, it's .030 over with a heathy single plane, Crane Cam etc, I didn't want to strangle the flow with stock heads. The numbers you suggested to me are where on a chart of gains? Very little gain, medium, good? Thanks.

 

[PRHeads]

Judging by the pics, it didn’t appear you took much material out of the areas that give the best initial “bang for the buck” in terms of effort expended vs flow gained.
So, again......judging by the pics...... it looks like there’s some fairly easy to extract cfm left on the table.
But...... when you really wanna know..... you have it tested.
If the number is as good as you hoped..... you’re done.
If they’re not, I could give you some pointers on what I’d do to glean a few more cfm out of them.
Then, you can still decide you’re done...... or you can go after it.

One thing is certain....... the flow bench doesn’t care what anyone “thinks” they’ll flow.

Many years ago, when the bought my first flow bench....... I spent a ton of time on some big valve 906’s. They flowed like 260.

I can get them to flow that now in less than 1/4 of the time it took me back then.
In the 26 years since then, I’ve learned how to get there more effectively.
————————————————————
I was just thinking back to that set of big valve 906’s from 26 years ago.
Prior to me buying a bench and reworking those heads..... again.... I was working at a performance engine shop...... this was like 1990.
I did the heads and ran the dyno there, but we had a guy we used to have do the porting jobs.
I prepped my 906’s with new guides and cut the seats for big valves, and I had the porting guy give me some pointers on what to do.
I had done some rudimentary bowl work in the past, but I wanted these to be pretty “good”.
I did a couple of test ports, he’d critique what I did, give me a few more pointers, I’d do more work, etc.
I finished the heads and was satisfied with how they came out..... they looked nice, and the car ran pretty well.

It was these same heads that I reworked again to get into the 260’s after I bought my bench.
I tested all 8 cylinders before I dove back into the porting on them. The 8 cylinder avg was 239cfm.
Even then I knew that wasn’t a very good number for as much time as I’d spent working on them.
I probably had 15-20hrs in them to that point........ and it was at least another 20hrs figuring out how to get them to 260 and not nose dive after .500 lift.

Nowadays, 260 out of 906 is a piece of cake, and I wouldn’t even rework the whole port to get it.
It’s like many things....... you don’t really get good at it without practice.

I’ll add this.......
If one is fairly serious about trying to get significantly more flow from these heads than they have in stock form, the principles discussed in the David Vizard book on porting SBC heads can be applied with good results.

The articles Dulcich did in 98/99 are also worth re-reading as a guide on where to grind and where not to.
That’s back when the articles had a little meat in them.

 

[Brandy]

Thanks, and I insist on reading up on stuff before I dive in. like piloting an Apache Longbow attack chopper...it's not something you can just go and do. I would be interested in pointers. I was kinda leery about fooling around next to the guides...

 

[Cranky]

Tear drop (both sides) the guides and stay off the seats!

 

[HEMI-ITIS]

Porter has been doing this for a long time!! Porting,specing cams.setting heads up and flow testing.Ghost,you are fortunate to be so close!!!

 

[Brandy]

Tear drop (both sides) the guides and stay off the seats!

yes, staying off the seats is a trick to be sure...lol.

 

[Brandy]

Porter has been doing this for a long time!! Porting,specing cams.setting heads up and flow testing.Goast,you are fortunate to be so close!!!

I AM thinking about dropping by. It's only about 45 miles or so. I was unaware of him till now...

 

[HEMI-ITIS]

One of the best guys out there!!How many gents that do this work would come on our forums and share all the years of he experience weather you give the work to him or NOT!
I know dozens of guys that send their heads,got them completely set up with valves,the right springs,retainers and locks! He is also an expert on choosing the matching cam!
I back him 100%