heads

I would say it depends what you are going to do with it. I have a 240ci motors in both my WC and do fine as far as my rules go and i have ported 3'' heads. There are good things about both heads. Alot of guys like the 4'' heads of the 45's and up but i had all the small hed and i made them work for me. If you are building a big RPM.... or Big cube motor the taller head has more  room for porting before getting into trouble..Just my opinion Im sure more people will correct me and give their opinion but this is what i know and it works good for me.

if you can get one I would use the 4'' head. That's way you have room to port. Depending on how big your going put bigger intake valves in. I also have heard that the big head the spark plugs pockets in the bottom of the head are not as receded in the 4'' head as well.

Im sure you can get away with a 4'' because even some late WD had the tall head... if I remember right. May be wrong...

I've got various old heads cut apart to see the internal coreing and how they're made.   I've spent more than a few hours of time porting on these heads and on the flow bench.

jpankey wrote: heres a wc head numbers stock with exception of valve job 28 inches on a 4.600 bore fixture. valve lift       cfm .100             67 .200              88 .300             107 .400             108 a z code gleaner same bore fixture same valve grind at 28 inches .100              68 .200              114 .300              129 .400              144 exhust no pipe wc head valve lift    cfm .100           62 .200           118 .300           140 .400           144 z gleaner exhaust .100           58 .200           105 .300           145 .400           172

You should take this as an opportunity to learn something pankey, not to argue. I'm going to explain why these numbers are not accurate, why you pay for a flow test and someone takes your money and gets you out of the shop as fast as possible. The man you are paying is probably quite good at this kind of work, but is in a hurry to get your $100 and get the "TVA clowns" out of the shop as like many others they simply do not know the difference.

Lets look at your .100" flow numbers for example. You say that of the two heads they flow 67 and 68 CFM at .100" lift with a 28"H2O depression which is pretty much standard when comparing numbers.

How big is the intake valve in these heads? Well you say it's stock heads you are comparing with a simple valve job. 1.688" is the intake valve diameter. Now lets look at the effective seat diameter you can have on a valve of this size. Say a 45 degree seat and even taking full advantage of that valve still leads to a throat diameter of X.XX"    Valve lift X valve seat area = valve curtain area.

Pay attention because this is important. Valve curtain area X 141 will = your potential valve flow. Now where does the 141 CFM per sq inch of curtain area come in? Research it. Though the valve seat and angles can be a very efficient orifice, quite often flow can exceed this number it's only by a small percentage. But flow through an orifice with a poor discharge coefficient such as a flat head like the ones you are testing will not. Now put a well shaped chamber around those valves and the flow can increase for all other things the same.

Why are your results showing about 40 CFM more than what they should show? Like I said earlier it goes back to getting someone out the shop as quick as possible, or simply not giving a hoot. Where's the leak? There's a lot of very well designed Chevy heads with 2.02" intake valves that flow in the low 60 at .100" lift, the 2.08" that flow in the higher 60's at .100" lift. These heads have a well shaped port and a well shaped chamber, a much better valve bowl to seat area than the old 226 Allis head. Actually these well designed heads when looking at the flow numbers will flow verry close to 200 CFM per sq inch of curtain area for the valve seat orifice. If we used that same ratio to your poor designed and shaped Allis head we would still only see just a tad over 40 CFM. How in the world do you get 67 and 68 CFM? When something doesn't make sense, figure out why. Are the valves being sucked open during the test? Head bolt holes exposed? Where's the leak? is the bench set correctly? Often a quick check will find the problem.       

Now as the valve lift is increased the flow numbers increase, we start to see how the port effects the heads flow, the more air moving through the port the more we can see how efficient a port is. Take the .400 lift numbers for example, if .400 is 4X .100 for valve curtain area and potential flow then why do we not see 4X the flow? The port restricts it, the shape of these Allis heads is terrible. That corner in them pretty much kills any flow improvements past about .350-400" valve lift. Start cutting the corner back and rolling the floor into a well shaped valve bowl and the numbers will increase.

Last but not least, exhaust ports should ALWAYSE be tested with a tube attached at least the port diameter. Otherwise the test simply isn't accurate. You wouldn't test an intake port without a radiused entry, those tests would not be accurate and the numbers would be useless. Exhaust flow testing is no different.

When I work on an engine, I figure how much air it will need, figure an estimate of what the carb and manifold being used will support and start to size a valve from there. Then is the valve way to big or to small for the port? From that point I start to make a compromise to make the best possible package with the given restrictions at hand.

Get some accurate results from tests, maybe put the head on your imaginary Superflow or Saenz in the corner opposite of your imaginary Gleason. Take some pictures and show us, when you learn something go build a real engine and go compete to show us what you know. Untill then run some numbers and scratch your head. Some of the numbers you have in your flow tests above are accurate and close to what I've seen, though some of them are very far off, not just a little off as in to be the difference from one head to another head, one day to the next.



Edited by wi50 - 12 Sep 2013 at 8:22am

The valve diameters was stock the valve angles weren't they were the same 5 angle job though.   If you test a good double hump sbc you will find the intakes flow 180 and the exhaust flows 140ish   . The allis head is reversed which is bad cause exhaust should only flow 80 percent like the sbc head .   This is why brother Ml has posted several times changing the cam so four straight exhaust ports were now intake ports would be a advantage but realize one should test the exhaust ports as intake ports before making the decision. A fellow once asked brother what a 1 3/8 inch port would potentially flow you can still find that post where brother replied . Ps when you start doing work for drag racers like Brian Mitchell let us know.

Edited by jpankey - 12 Sep 2013 at 6:37pm

One question, what does any of this have to do with the original thread?! I just wanted to know if there was any advantage to using one head over their other!

The purpose of my post mufflerbolts was to mathematically show that there are some people here who simply have no idea what they are talking about and that their information is as useless as the bandwidth taken up buy it.

Nothing against you WI or anyone alike, the thread was headed towards an argument that would have traveled far from the point. I appreciate all your input and intend to call you soon for answers about my winter project. It was asked because there are others that bring up stuff that I get tired of reading through also don't really care about small blocks or race engines, suppose to be about pulling engines. To me they are far cry to be the same thing. Or correct me if I'm wrong.

Sure would be nice to get through one or two technical postings on this forum without the VI mucking it up wouldn't it??? 

Here we go again... 

"When I work on an engine, I figure how much air it will need, figure an estimate of what the carb and manifold being used will support and start to size a valve from there. Then is the valve way to big or to small for the port? From that point I start to make a compromise to make the best possible package with the given restrictions at hand."

I missed the RFD tv pulls. I'll have to watch for the repeat.

DonDittmar wrote: Just saw Marty pull on the RFD pulls in Tomah!!

I just seen that, someone sent it to me. We had a job over 100 miles away last night and I wasn't able to be home, nor did I know it was on.

By far not a great run, but good enough to get down the track, I think it was the 4th run on the new engine, turbos and fuel system. It was running very cold, rich on fuel, so I brought the boost up to try and burn that fuel up and hopefully make another several hundred HP, get the exhaust temps up where they needed to be. It all makes sense, but in reality, the extra air pressure closes the fuel returns off (boost sensors on the fuel tank) faster and harder and floods the engine worse than before. I was a gear to low also, the day before most of the tractors went to sleep in the mid 200's for distance down the track, it pulled so hard down there that most of them just wouldn't build enough torque to pull through it. We dropped a gear, and with the fuel being rich it was a good combination and we did quite well. Saturday though I should have been a gear faster.

After Tomah I plumbed the idle different and took some fuel away from the idle circuit and got it to light quicker, then shimmed the P valves higher to hold the mid and high stages back for a few more RPM, within a couple weeks I had it running real good, good enough to get by some of the very good tractors a couple times. It just seams like it takes a dozen runs to get things tuned closer. Second chances are to expensive, so small adjustments at a time. Winter upgrades are a MSD Pro Mag 44 for ignition, different valves and springs in the head and hopefully some sheet metal and decal upgrades.

no cylinder head on the market will flow 141cfm a square inch Not even a hemi head. 80 to 113 yes and sometimes at 113 power suffers from the cfm loss at low lift can not be made up .

jpankey wrote: Half the battle is to know where to purchase performance.

Yup, that why I and a lot of others on here have all purchased quailty heads, cams, or rotating assemblies from Wi. Imagine that! Stuff that works like he says it will!

You bring up someones name and I talk to them, and its a fight because that cant dis-associate themselves with your name fast enough!