[Half-Inch Stud]

Documenting the mods made across 38 years of "learnin" on a set of 48s. Heckleing and abuse is expected. Eye-opening too. Something for everyone here. Cast Iron Heads Rule in Reliability.

What you see here are 48s gotten for $40 in 1982-83 during my Penn State days. A Local took his 69 Judge apart and was selling stuff, so a notoroius former PY member & I were always on the hunt, and stopped-by for a looksy.

Another enthusiast at that time&place recently bought my 5Cs, so now i am left with these buggers for my Spare 462. These 48s started out in the 13s, and eventually ran the 12.2 ET in the signature below.

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The 5Cs were going to be the heads for my 462 Spare. They measured 98cc whereas the 48s measered 78cc. The Pipet is handy, and you can get one for $44 from Thompson
Scientific.

I used a 1-cup Pyrex to fill the 50cc pipet, then drained into CYL twice. You could check all 8 if you are uptight that way. Technique: break surface tension zones for best result.

Who cares; i do so the Spare can be ping-free on 87 Octane, just like the 68 GTO is with Ram Air IIs..

455 +030 .005" proud. 0deck .023" in the hole
5Cs 98cc __11.93:1 __ 11.79:1 ___11.19:1
48s 78cc __9.88:1 ___ 9.79:1 ____ 9.39:1. per wallaceracing.com

5Cs would be excellent but i slod em: they are like the RA IIs; no mistakes in porting. More on that later.

[Half-Inch Stud]

Mistake1:
In the mid 80s i bought new NOS Ram Air IV valves (Intakes are 9794021) and took the heads to a "Machine Shop". I wanted a valve job and spring pressures set. Well, they finished and called me. I lool and see the shop STAMPED the CHAMBERS and VALVES.

Piece of my mind went loudly to the shop owner for stamping the valves, and the Chambers: the valves are hard steel, like crystalline, and the Chambers are actually delicate, not even GM numbering Super Large Font in the Chambers and DEEP.

Luckly the font used on the valves is tiny. Eventually, the Exhaust valve tossed in the creek and replaced with Ferrea 5063.

Lesson: Tell Machineshop to NOT stamp any valves or Heads surfaces: use a Sharpie.

[Half-Inch Stud]

Mid-80s "Drag Racing" at Maple Grove and scored 13.2s with rather stock stuff, and probably over-rev'd. time for porting! ( really it was time for an electric fuel pump ).

Mistake 2: Got a Sears hi-speed Grinder and a Roundtree bit, and removed iron. 48 head photos can reveal grinder marks ( chatter, bad bearing, delerium, etc ). After a few Roundtree bits, no more. No such grinder& Bit for over a decade now.

Lesson: The tools shown below are soo much better to achieve better results. $39 each these days at Harbor Freight. I got a 2nd grinder because of the Value there; not Mikito but...China! 60 & 120 grit Belts from McMaster-Carr in 25 QTY for cheap.
A "Racer" will go finer than 120 grit. Not me.

[Half-Inch Stud]

Along the way, i had a set of 48s ported by Tom Slawco while at BCHS ( Brandywine); no epoxy no leaks, and fantastic quality. those went 11.00 and 12.00 in Signatures below. I mapped the heads out, and sold the car ��. Those heads had large intake runners beyond RA IV bigly, minor EXH bowl cleanup, and no chamber mods evident.

Rest assured the R 96 A heads, and the 5C heads would receive a MINIMALIST treatment. Hmmm, a few photos on tools;

Washers for checking the Short Turn AREA: Exhaust and Intake. Note the diameters.
Rods for checking the Intake Runner (Heads and Intakes) WIDTH and HEIGHT

The 2 checking-Rods are very important and a "Best Practice"; short rod to guide belt-sanding the Pushrod Buldge down. The Pushrod Buldge is the first CHOKE in flow. The Long rod is for getting Runner Height just right. Never broke through a casting, and sure don't want eggshell results.

A set of Excel Calcs will help YOU see the original Factory size for CSA, vs the goals needed to make a CSA improvement.
A set of precise FelPro 90123 (old number) gaskets help (i will show Counterfeit 90123s from China! EBAY as evident by the lack of precision). $6 China 90123s are good for belt-sanding to match the Cast iron openings.

Pushrod buldge and Bowl shaping is the only Porting needed for dramatic Street/Strip improvement. Any extra porting must have purpose or it is just to feel better.

Valve Guide cutting tool for 0.50" OD guides. Also cuts the ID location for Inner Spring from Butler in 2010. DONE on R96As but not done on these 48s. SPOTTS Performance provided Springs and Shims with inner spring Locator for these 48s...from Paul in 2010.

Geeky Flow Bench parts shown. 3HP electric motors: 1 with 5" vacuum Cleaner Impeller, 1 with Turbo compressor Impeller. I actuall ran these in series for 2-Stage air supply. Pair of 300 Amp controllers remained reliable with about 130 Amps at 32 VDC. So these heads were "Ported for lowest Noise" and run to 12.2 ET.

The R96As got the "low noise" treatment and also ran 12.2 ET but were stock Runner height. r96As were Tall-Ported to the Slawco 48 size, and the 1/4 mile data is pending.

[694.1]

Good stuff. And what kinda dumb arse would stamp chambers & valves??

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Man oh Man. Here is the 10 foot Manometer used to observe flow depression, or "flow".

I think 8' is sufficient for at-home efforts. Can ever start with 4' and upgrade if you max-it-out. The geeks can go with a digital mamometer. I didn't. Maybe an Analog Man afterall.

The prior Post showed the Calibrated Orifice Plate; a flat plate with 2.000" hole centered within a 4" PVC pipe. Excel file is used to document the design for the "beta" chosen, but you can just build one and use it. Famously accurate but has inefficient flow compared to a Venturi version ( innacurate until carefully profile-calibrated). COP is used when you have plenty of air flow with plenty of depression. Venturi is used when you got plenty of flow but precious little depression. I went for flow numbers by reading the Manometer and use Excel to see the flow as told by the 2" COP plate.

Also helps to have a known quantity. A flow-tested item to act as a single-point calibration check. I have a 455+060 size Cylinder adapted to 2 1/8 ID pipet that checked out as 400 CFM @16" and 396 CFM @14" (1/2 PSI). Measured by Chris "blacktopr" long ago.

Frankly, i grew tired of "Flow Numbers" and aimed for least turbulence (choking) INDICATED by least noise. Turbulent Noise during the valve event is completely indicative of a bad runner. Geez, when you undo the turbulent noise the flow is there. I figured the Excel calcs using CSA (likely the CSA at the pushrod buldge for Street/Strip readers), the min CSA. Racers will want acceleration.

THEORY, Perhaps Half-Baked; 350 fps is a great room-temperature runner velocity goal. Assuming a fella has attained Uniform velocity across the CSA. Then, 78 CFM for every 50 HP is a metric. Perhaps thee metric for 2-strokes. so a 4-stroke metric might be 78 cfm for evety 25 HP. Regardless of the exact metric, the flow goal can be related to HP. Existing 1/4 mile performance and the HP can generate the metric for realized CFM. Then gin-up the neded CFM for the desired improved 1/4 mile. The inhale minimum CSA with 350 fps flow attains the HP result.

NOTE: i strongly encourage that if you try flow-testing; design for an absolute quiet arrangement ( motor outside with straight pipe to COP or Venturi ) then test away at bench height, for noise reduction, not flow numbers. Methods to inspect flow can be discussed

[Tom Vaught]

MORE COMMON THAN YOU THINK. I ran across two "speed shops", in the Detroit area,
that did the same thing. Hack Jobs. Very easy when you are doing the valve job and cylinder heads to know that the passenger head has the water nipple (65 and later), and
the drivers side head can only go on one way once you realize which head is the passenger side head. I used masking tape on the stems of the valves after they were ground and checked for the specific cylinder in the head.

Tom V.

[Half-Inch Stud]

Originally Posted by 694.1

Good stuff. And what kinda dumb arse would stamp chambers & valves??

That Machine Shop (Phoenixville Machine Shop) was outdated and went outta Biz about 2-years later circa late 80s-early 90s. They rebuilt Starters, Alternators, Heads, Blocks and sent the Cranks out. Since then i discovered excellence Machine Shops.

Is amazing that automotive Machine Shops can just about go on "verbals" for very precise Crank/Block/Head wants. Whereas, the DoD military programs gin-up ANSI-STD Drawings to describe a stupid-easy part and the Machine Shop charges higher fees. Do machinist doing precise work leave the automotive shops to do largess work at a Shop dedicated to DoD work?

[Tom Vaught]

So your home built bench can flow at 120 inches of water depression?

Ford Motor Company's research bench tests at 67 inches of test pressure and they need a massive electric motor to spin the blower to create the test pressure. That bench cost 3.5 million dollars.

Post up some pictures of this bad boy flow bench.
What did YOU use to create the flow depression across the head?

Tom V.

[Half-Inch Stud]

Stamping...geez. How much easier to sharpie the numbers, like onto the stems.

The 48s first got the Red Paint treatment long ago. Something I figued back then with OHC6 Cam Towers and engines. Touched-up the letters last night.

Awaiting valve Seals from Bulter's. Comment away.

[Half-Inch Stud]

Originally Posted by Tom Vaught

So your home built bench can flow at 120 inches of water depression?

Ford Motor Company's research bench tests at 67 inches of test pressure....
Post up some pictures of this bad boy flow bench.
What did YOU use to create the flow depression across the head?
Tom V.

Yea funny. Good catch though. 120" at like 7 CFM or something, and as you know the depression goes down as the flow goes up. I have a plot of depression vs CFM when flowing through the 2.000" COP, (will check the folder soon). The bench went pencils down until a venturi could be made-and calibrated.

Edit update: The Plot shows;
the House Central Vacuum can attain 45" to 70 CFM then droops to 10" at 200 CFM
One Turbo Volute attained 50" to 100 CFM then droops to 18" at 230 CFM.
Series 2-Stage Turbo Volutes did NOT get plotted for flow because the COP is stupid restrictive to cause early over-current. and I desire a venturi. The 2-stage would draw excess current (> 120 Amps at 32 Volts when run into the COP. 67" @ 60 CFM or 64" @ 70 CFM is the only interesting high-depr datapoint before current limiting. Whereas the Intake Runner is less restrictive yet no COP, so no measured depression to report there. Happy to test through a cal'd venturi having round CSA on the order of whatever 2.3" x 1.2" calcs to.

As you know, real combustion engine depression vs Intake valve lift is quite a dynamic depression for the dynamic flow. When porting for least noise any depression in the teens is darn plenty for valve lifts from 0.3" up to a headless valvestem.

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Just remembered. The turbo volute motor evals were done with my Bench supplies (Acopian, near Allentown PA) with an artificial 70 Amp motor current limit chosen, with supplies capable of 120 Amps. Since then, i put a lead-Acid in series for ~43 VDC and did brief runs (wow to say the least). Then decided that 3 lead-acids in series would do be the better source at about 36 VDC and the motors could safely draw 140 Amps and brief runs to 170 Amps.
Plenty of "supply-side" flow.

For Tom; I think the 4" PVC pipe to house the 2.000" orifice plate was a poor choice for efficiency; the intense effort to develop velocity in the turbo got lost with expansion in the 4" COP. I got convinced that the flow "bench" ought be made from a constant CSA pipe system to preserve supply velocity. Preferable completely straight too, up to the measurement item. Perhaps up to my cylinder cup (2.18" to 4.21") which may represent a piston in mid stroke rather well.

CSA _____r^2 __radius Pipe ID item
2.405 sq" 0.76__0.875"_ 1.75" TURBO volute outlet dia
3.398 sq" 1.082_1.04"__ 2.08" PVC Pipe ID
3.55 sq" 1.13___1.13"__ 2.18" Steel exhaust pipe
4.16 sq" 1.323__1.323"_ 2.38" PVC Pipe Sleeve union

A 1.75" steel pipe system might be best, but somehow I worked with 2.08" ID PVC pipe for cost, compatabilities with the Turbo shells, the COP, and at-home activity. A 1.75" Steel pipe system might be best. But what venturi max-min dimensions?

Simple Intake runner schedule ( actual runner values in some excel file)

CSA_____Height x Width
1.89 sq" 2.1" x 0.9"
2.1 sq" 2.1" x 1.0"
2.2 sq" 2.2" x 1.0"
2.3 sq" 2.3" x 1.0"
2.53 sq" 2.3" x 1.1"
2.76 sq" 2.4" x 1.2". (i"m loosly aware of the taller/wide ports, but i'm also stuck to iron heads for Street/Strip)

[4dblnkldude]

Mark, you are doing and have done a lot with what you had/got. With the knowledge here you should be able to keep your boiler going for another 40 years.

[Half-Inch Stud]

The Flow "Bench" drama is a necessary side-story for Head work, and is based on performance need, and an interest in efficiency qualities, but other interest like wife, kids (now 6 grandkids), good times and that assumption called a career had put a pause to the "Next Steps"; the Venturi Tube. Darndest thing is i happen to enjoy our hobby. Part of being a retro introvert.

Last night: was able to sketch a venturi tube with dimensions, materials, and design performance that assures "lowest noise" of all delta-pressure flow dression devices. And i remembered doing a rabbit-hole pursuit using the Mass Air Flow assemblies by FORD/Lincoln. Being an EE, i figured the MAF assembly was "too electrical" for at-home play. There you go.

Turbulent flow in PMD Heads: Everyone that ports Heads for a living have known WHY flow numbers stall to 210-225 CFM on Pontiac Heads, around 0.35" lift give or take a little. Otherwise they'd fail in their craft.

My opinion: the Short-Turn with Bowl manifests the turbulent choke. The fix is upstream at the Pushrod buldge, or/and the floor shape. The air needs to be laminar, or " attached" to the wall shape. Soon as air hits a "shock surface" that air bunches-up and cuts into the mainstream air and BOOM, the huge sucking sound of stalled flow.

Aero-design is all about making the incoming air flow along the surfaces you want. "Control Surfaces" need the air "attached" otherwise the control "stalls". "In-Pipe" air flow versus external air flow is a dramatic subject for me where In-Pipe is deadly-accurate in Simulation ( flow, pressure, modes, thermal transfer, shock, noise). Yet external (airplane stuff is utter fake, phoney, and false: because the Simulations all move the air and keep the aircraft still. Every reasonable person wants the air still and the aircraft moving.

Air is a brazillion little springs in equilibrium, mildly sticky too due to the 14 PSI around. Move the air and the air is "energized" with momentum, and elastic properties (energized PSI) keep the air together. Whereas, move a wing through Still air and the impacted air pushes on other air ( under natural PSI). Energized PSI is known as "Dirty air" and natural PSI is called "Clean air". All external SIMs known to me use "dirty air", except 1 set of code which under propriety i cannot share.

My biggest point for showing false SIM results occurs with Biplane wing stagger (2-wings). All SIMs predict Positive Stagger and modest lift improvement, whereas real life favors Negative Stagger and increased lift, versus 1-Wing. A fiesty fella can make money and a biz getting that.

But i digress, CYL Head porting is all "In-Pipe" flow, so the SIMs are deadly accurate. Good luck entering the port shape, and making design changes. Those design changes happen better-faster in the lab under flow observations (ear, velocity probe, little cotton string on a 16-18 gauge copper wire, and spray paint if you must. The lab flow work "live porting" is the fastest route to an optimized design. Boom, there you have that.

Enough Flow drama, from mee.��

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Flow motor tune: when building your own flow motor (vacuum motor is a good start, brushless is a resonably better result);

The impeller will pull towards the suction surface side during high depression. So is completely worthwhile to avoid the 120" depression performance at 0 CFM, and increase the suction-side gap for low-flow suction limit around 60-70". A uniform depression will result from 0 CFM to about 70-100 CFM and dramatically increased reliability when the Intake Valve is shut. no penalty to the depression at high-flow CFMs.

Note: we ordered Central Vacuum for every home i've owned. The Central Vacuum is a win-win for home and hobby. Just do that, because the CVac is sufficient to incite the Intake runner stall at 0.35" lift. Yet know that stall can come and go with depression level, and Intake Manifold runner angle.
Note: Central Vac hoses can be quiet or self-turbulent and mode badly into a whistle noise. So feel free to return a noisey hose for an upgrade. I did and the Seller agreed that whistle noise happens and shouldn't be accepted. (was the cheap hose for my garage hose ��)

Hmmm, I strongly suggest that some Manifolds induce 4- choked CYlinders, and 4 flowing Cylinders. Particularly evident with aftermarket Dual-planes. Factory Dual-Plane can succeed for all 8 unchoked due to pre-conditioning the flow before the pushrod buldge.

What is to say for Heads where the Pushrod buldge is taked down! Has the least CSA with the most deflection into the mainstream! Makes the Short-Turn a minor deal.

[Shiny]

Good education, thanks!

I'm curious how much the mixture of fuel vapor and air affects both flow and testing. Do your software tools allow simulating mixtures of air and gas?

I know water vapor is highly influential around surfaces. I suspect there is a high saturation vapor pressure for gasoline so the mass of the gasoline and localized condensation are probably big factors inside manifolds and heads.

[Half-Inch Stud]

Wet-Flow is done in the lab setting. blacktopr posted youtube videos long ago when wet-flow testing was in its infancy.
Wet-flow can be Simulated In-Pipe. usually 100%air or 100%fluid, not sure about humid air ratios in-pipe. 1:12 ratios for in-pipe SIM sounds flakey but perhaps insightful if possible. And not SIM'd by me.

Fuel gets into the air flow just fine with a carburator, hit or miss on fuel injection. But the serious problem for carbs would be the Intake valve shutting which causes that fuel to cradh into the valve backside. We all run a tad richer than theory there.

Both FI and carb'd also have the fuel drop out of "suspension" upon impacting the Piston. The hope there is the hot piston re-vaporizes fuel on the upstroke for Spark-ignite. Coatings or bare aluminum are waaay better than carbon-coated. Chmber and CYL wall wetting aftertheLong-turn" in the bowl isanother inefficiency. PMD may have kept a high-brow on the chamber scallop-cut to keep the CYL wall and chamber dry. These 48s would have ruined that if so.

[Tom Vaught]

A Superflow 1200 Flow bench carb/head flow bench like Wilson manifolds uses has 16 of the best Ametek Vacuum Motors out there and required over 80 amps of 220 power to perform tests. And it still is not perfect vs the Ford bench by any means.

Your simple flow bench gives to general "suggestions" on what to do.
Even a simple Superflow in the right hands can give you good info (bench has TWO vacuum motors).

Tom V.

[Half-Inch Stud]

@Tom, sounds about right for 16 motors at 220 VAC. I had 7 motors gaggled and ran it. I shifted to the 3 hp brushless jobbies with turbo shells.

Imaging those Amateks turning 22,000 RPM or so versus 1 of my brushless jobbies turning the same vacuum impeller 58,000 RPM or so. No comparison.
.