kitfoxdave

This is a compilation of the data Cutlassefi has posted on the forum. If you do a thread search under Cutlassefi, you will find the original data used to put this together. Hopefully this will help understand different heads and work done to them. (I do not have data on a standard OEM head that has not been cleaned up, If someone has that data I would be glad to edit the spreadsheet to add it in.) Base line for percentages is a cleaned up 7a cast iron head.

cutlassefi

Thank you for compiling my info and essentially doing my job!!!!

A word of note. Some of you are concerned about the loss of velocity thru the port on a BBO head (or aftermarket head) vs a SBO.
Notice one thing, at no point does the "larger" port lose any velocity. How do we know that? Simple, low lift flow. Even though there are significant gains from a blended 7a to a CNC'd aluminum at .300 and above, the low lift flow (.100, .200) never suffered. In fact it even picked up flow there as well on top of using a 2.125" valve vs a 2.00". I think this says it all.

Imo if you need to spend more than $500.00 on a set of irons you're wasting your money. I think this is indisputable proof of the potential in an aftermarket head vs the stock irons.

kitfoxdave

Glad that I could help out! Again a BIG thank you for getting the data!


Having the info in this format really helps to see what improvements you can get.
If there is any more cost guestimates for the "cost" row, we can get a better idea of bang for the buck.

kitfoxdave

here are the links to the original threads:
Knowltens:
https://classicoldsmobile.com/forums...head-flow.html
ProComp and Edelbrock:
https://classicoldsmobile.com/forums...edelbrock.html
7a heads:
https://classicoldsmobile.com/forums...w-numbers.html

Kyle's 77 Cutlass

So the 7a's, is that ported?

kitfoxdave

The 7a head just had the bowls blended, valve job and dividers welded in with a little bit of clean up. Not ported.

Kyle's 77 Cutlass

So if they were ported to the nine's, would be comparable to edelbrocks out of bock?

f-85

Do you have any stock flow numbers from a BIG block head big valve head a, b , c ,e ,g?

I'd like to see a straight up comparison on your bench with a big block port.

Old chamber edelbrocks or new?

67 Cutlass Freak

J-(Chicago) posted this on an older thread-


Stock flow numbers according to midamericaperformance:
BIG BLOCK PORTS (STOCK)


Valve Lift
A B C D E F G&Ga H J Ka

.100 84 85 85 92 89 92 91 87 81 85
.200 159 159 162 164 156 165 158 159 144 157
.300 208 209 211 207 215 210 205 209 206 209
.400 233 232 233 228 243 227 225 232 223 224
.450 243 244 244 233 246 234 231 239 225 231
.500 250 250 250 239 250 240 236 243 227 236
.550 254 253 253 243 252 242 237 245 227 237
.600 259 258 259 245 253 244 239 248 227 239


BIG BLOCK PORTS (STOCK)


Valve Lift A B C D E F G&Ga H J Ka

.100 54 50 49 50 48 49 47 50 49 47
.200 101 99 99 98 92 99 96 98 89 94
.300 135 133 133 133 127 129 129 131 121 126
.400 151 146 145 147 147 144 145 147 125 144
.450 154 152 151 153 153 148 151 153 126 149
.500 160 158 158 157 158 154 156 158 126 156
.550 163 161 160 162 162 158 158 162 127 150
.600 169 163 162 166 166 162 161 165 127 161

kitfoxdave

OK, I did some searching through the threads (using j-(Chicago)) and found some data, also found a few posts saying do not believe Mid America Performance flow numbers... So. Let me play with excel a bit more and create a second sheet with that data... Also there was some data for a stock 7a head posted by j-(Chicago)... any more detail on that test? location? date? temperatures?

f-85

Yeah those numbers are way high. I think his flow bench was alittle happy. I would like to see some stock BB flow numbers from marks bench.

cutlassefi

I have an old set of E's lying around somewhere. I'll see if I can get Champion to flow those as well.
The Procomps are the old style chamber, the Edelbrocks are the new style.

f-85

Thanks Mark. Im pocket porting a set of big valve Cs now. Im just doing 2 ports. Then having the 2 stock ports flowed and the 2 ported ports flowed. I want to see what the baseline is and then what alittle port work does.

cutlassefi

Flow wise yes, overall performance potential? No.

Kyle's 77 Cutlass

So they made edelbrocks, bigger valves, bowl size different, spark plug location?

cutlassefi

It's just a better cylinder head, all around.

Kyle's 77 Cutlass

You would gain 10% to 20% more power with those heads?

kitfoxdave

I wish we would have thought about flowing my 7a's before and after... Oh well...

cutlassefi

There's some flow info on a set of stock 7a's on ROP. The figures seem consistent with what I've seen in the past.

cutlassefi

Depends on the combination of pieces.

J-(Chicago)

Yes. there has been some debate over midamerica's flow numbers. I would take take those with a grain of salt. I have no affiliation with them, it was simply the only rough baseline online info at the time that i could locate When I posted them.

I would trust numbers from a real olds guy such as J&S machine on jim's website, because i'd doubt he inflated his numbers before I'd trust a random internet source. You never know though. I'm sure he's in the business of staying in business as well. lol.

J-(Chicago)

Also, not to stir up any crap, but flow numbers may be inflated by designated dealers of certain head brands, so take those with a grain of salt as well.

I deal no brands of parts, and only post real, original OLDS iron numbers when I obtain them nowadays.

I have no aluminum heads at my shop, and still firmly believe that unless you are trying to make more than 500 horsepower with a big block, the aluminum heads aren't even worth the bother IF you can find a decent porter for a good price. Out of the box, the aluminum heads may need machine need work anyway......(Depending on the goal.) In fact, Everything depends on the goals. PURPOSE BUILT machinery is the most import theme for any car.

J-(Chicago)

Here's some #4A head flow numbers that I personally have no reason to doubt. That Jim at J&S machine did.

Again, I wasn't there, but since field data seems to be one of the goals here so far.... Here they are. He is an iron head modifier and dealer however, so believe what you like. here's the link and the numbers...
http://www.jsmachineoldsmobile.com/4As.html
lift int. ex.
.100 56.7 43.9
.200 117.4 82.8
.300 160.3 102.6
.400 184.8 110.9
.500 190.6 115.4
.600 194.8 119.1
Avg. flow #'s
int. 150.7 ex. 82.1
lift int. ex
.100 70.2 55.5
.200 134.4 102.6
.300 180.3 129.8
.400 219.6 149.2
.500 235.7 156.8
.600 237.2 163.8
AVG. flow #'s
int.179.5 Ex. 108.2

cutlassefi

I couldn't disagree more. To spend more than a few hundred bucks on outdated, inefficient iron heads is ludicrous. Especially when you can get ready to run aluminums for $1100.00 to your door.

kitfoxdave

Were your 7a heads flow tested at J&S Machine?


Thanks for the data!

olds 307 and 403

Even if J+S numbers are high, at least he has a baseline. The exhaust flowed what I expected on the 4A but the intake better stock than I expected. I hope to hit around 200/150 on my #8's. I would rather do the basics being my first set ported, then going nuts and losing flow.

kitfoxdave

I added in J&S Machine numbers for 4A heads and J-(Chicago) 7a base heads info data that I have.


The 4A heads data is a before and after comparison,


The 7A data I used as a baseline to compare the heads to the right...
Keep in mind the data is from DIFFERENT sources, so expect variation!


I did NOT include the Flow numbers from Mid America on the BB heads as they do not seem to correlate well with other data... (happy flow bench?) When I get some good data for the BB heads I will include it in the comparison chart.


Dave

Smitty275

Well, this is the fourth time I've tried to post to this thread. For some reason I cannot do it from my phone and the last time Internet Explorer decided to stop working and toss my info in the stratosphere. So this time it's word pad and then cut and past. So it might be longer than planned since I can take a break if I want to.


The Mid-Am site is a joke. They will publish what ever information someone gives them, yet they won't correct it when you ask them to if it about your specific name and product. I finally had to take other steps to get the info removed about the heads I have offered over the years because the info they published was not even close to being correct. They also could not tell me where the info came from, which I though was a bit careless on their part.


Now with that said I'll try to post up some constructive information from my experiences. I'm sure there will be other opinions and that's fine. But my 30+yrs building these Oldsmobile beasts, and a lot of other makes also, should be worth something. Even if it's just a different point of view.


I somewhat agree with not putting a lot of money into a set of iron castings. Sometimes it is a better way to go depending on circumstances and results desired. Before the release of the ProComp heads I felt differently about that. The Edelbrocks just add another layer to the offerings that we have and a good one at that. The only problem with either of these heads is the use of a stock style fuel pump on the SBOs. It's either electric or cut an area out of the head and patch it back in so you have clearance for the pump.

With the ProComp heads they make rebuilding a set of irons about obsolete unless your building a sleeper. I feel that these heads if purchased assembled are nice for a mild 350 build. Why, because the runners are small and the pinchpoint very small. THat makes teh velocity wicked fast. Another thing I have found with them is that the chambers are usually huge at 84cc. So cutting the decks to make the chambers useful is just about mandatory for almost any application.

The Edelbrocks are a fine head. Not two ways to look at it. While they recently changed the chamber design and slightly changed the intake runners I don't see much performance difference between the two versions. They are well suited for mild to hot SBO builds and mild to warm BBO builds, just the way they are supplied from Edelbrock.

Once you get beyond basic engine building and are going for that really hot build be it SBO or BBO I'd start with a set of bare ProComp castings. They are every bit as good of a casting as the Edelbrock from what I have seen and once ported it doesn't matter what the original configuration or manufacturer was. So you may as well have an extra couple hundred bucks to put into the porting and hardware or cam/lifters or wherever you could best spend it.


My best advice for having aluminum, or iron heads for that matter, ported is to give your porter BARE CASTINGS, or buy the bare castins from him. Let the porter size and supply the valves as he is the one making the head do what you want it to do. Don't be hung up on something you read somewhere as being all the rage. Valve size and shape, and how the valve job is cut on the seat have an amazingly big effect on how the port work done will respond. Take two otherwise identical ports and change one thing, valve, valve job angles, seat angles, etc and you can have differences as much as 30cfm. So let your porter make those decisions. Besides, should the head not make power, you don't want him to come back at you with a handful of good reasons because you took it out of his hands when it was most important to leave it in his hands.

As for trusting infromation about what heads flow: For the most part, only trust those who "OWN" a commercial flow bench if your going to be looking at numbers. Also don't trust numbers from a head flown at 5" and converted to 28". It's just not comparable. Many times I've had people bring me a head to test that they got from porter X that had these awesome numbers at low lifts. Well, the reason they have awesome numbers is because the porter didn't have a bench. When he had another outfit flow it they didn't bother to put a spark plug in it. I would flow the head with customer standing there in my shop and spark plug in place and get very normal average numbers. They pull out their sheet and say my bench must be wrong because that head flows XXX at .100 lift. So I tell them what I think the difference is. Yep, the spark plug was missing when their sheet was made. I pull it out and the numbers jump right up to where their sheet says it should be. Well, I tend to run my engines with spark plugs in the holes where they belong so I figure I should test them that way also. Anytime you have a porter tall you their heads flow over 100cfm at .100 lift and a valve under 2.500 OD be overly cautious doing business with them. Not even the absolute best world premier porters in the business achieve that. Also don't fall for the low lift is more important line. .100 lift is not that important at all. I really don't even like to bother with it. The cam goes through the low lift ranges so fast that they have very little effect on total flow through the lift curve. Examples; With a .500 lift hydraulic cam you need to be worried about .200-.500 flow. With a .700+ lift solid roller .350 or .400 up to peak lift is what will make the difference.

So there is my two cents worth. Now to go upstairs and see if I'm still married after being on the 'puter typing along with playing with the dogs for the last hour and a half on a Friday night.

P.S. The numbers "cutlassefi" posts are pretty much the same as what I get here on my bench. I know we have both had heads from the same source to be able to compare my numbers to his posts. So I would believe his numbers on head flow.

cutlassefi

Hey Dave,

I just posted these numbers over at "Aftermarket vs Ported Irons". You can add these to your spreadsheet if you like.

Ported "B" Heads done by Mulder Machine in Idaho Falls Idaho. 2.07/1.71 valves, 12-15 hours to port and fill crossover etc.
Intake
.200 141
.300 196
.400 235
.500 247
.550 256
.600 264
.650 269

Exhaust
.200 113
.300 154
.400 171
.500 184
.550 191
.600 193
.650 197

Done at 28".

Thanks!!

J-(Chicago)

No my 7a heads were sent up to Rocket Racing in Wisconsin. Whether they flowed them in house, or subbed out that job, I am unsure of. It was just a part of the punch list that I gave them.

Good post, Mark.

J-(Chicago)

Also, nothing was done to the exhaust dividers on the 7a heads.
Just wanted to see what a simple big valve install and simple bowl blend would pick up.

The goal was to make a lot of throttle response, so it would be easier to catch a good light, and hopefully a good 60' as a footbrake street car.

The only thing I would change probably, would be to mill the exhaust side down flush with the divider instead of debating which one to mess with (all those clips , goop, and welding and what not). My headers still have plenty of room to have done that.

Good work on the chart, Dave.

kitfoxdave

Cutlassefi, I am out of town until next weekend, I will add the data then. THANKS!

J Chicago, I'll update the info to reflect Rocket Racing... I appreciate the info!

I just hope it helps people make up their minds as to what they want to do and a rough guess at cost to do it.

Smitty275

Jim of J&S does not have an in house flow bench. He verified that on ROP not long ago.

J-(Chicago)

We need flow numbers of complete head and intake setups now to make this worth a hoot.... do we not? That would be a lot easier to use with Meaux's calculators.

olds 307 and 403

Here is a question, what about the plugs that come with the RPM intake? Do they do any good or just eventually come loose and rattle? Also what about a bowl hog when doing a valve job? I know a Mopar magazine did an article on stock head flow, when they installed larger valves they did flow with and without the cut. The heads with the cut picked up flow and less porting was needed to reach full potential.

cutlassefi

[QUOTE=olds 307 and 403;639830]Here is a question, what about the plugs that come with the RPM intake? Do they do any good or just eventually come loose and rattle?[QUOTE]

Imo I think they're useless. They block off some of the heat to the intake but do nothing to help scavenging in the center cylinders as they don't totally isolate those exhaust ports.

midrange

They come loose and rattle. I had the passenger side come loose after only 50 miles on the rebuild. The engine builder fixed it for me at no cost.
The driver side came loose 2 months later.
If I would have had the extra money when I had the engine built, I would have never put the irons back on.
I'm pulling the irons off and installing aluminum heads this spring.
I'm monitoring these head threads closely in order to decide if I go with Procomps from Mondello or Edlebrocks.

76olds

I'm also monitoring the thread as well. I will be adding more upgrades this spring to my sbo

Fun71

Many years ago I put the info from the MidAm site into a spreadsheet. Not sure how valuable it is, but if you want it let me know.

kitfoxdave

Updated spreadsheet:


I already have data for mid America entered in my spreadsheet... It is hidden because it is way out of whack by comparison to other data from many sources. Thank you though for the kind thought!