Draw through setup

Carb PV modification thread.
viewtopic.php?f=22&t=74210
A Holley 600 DP would get the job done much better than the 500 Eddy.
Don't forget that at 15 lbs of boost (Neglecting the loss of airflow due to heat) the turbo inlet flow in CFM is double the engine flow in CFM.

With the stock cam + 1.7 rockers and some port work, the peak Volumetric Efficiency is just under 2500 rpm and it falls off from that point.
That's just about the time you are making good boost so the engine is working against the turbo in making power.
The longer duration cam will move the peak VE up so the engine can take advantage of full boost.

On this engine I'm going to recommend the Crower 19213.
http://www.crower.com/camshafts/ford-24 ... 6-hdp.html
Ignore the description. It is overboard compared to the actual performance.
/viewtopic.php?f=2&t=74629&start=50

On future builds with better components you can look at much bigger cams and back to 1.6 ratio rockers.
With this cam and boost, the closed spring pressure needs to be around 125 lbs with close to 280 lbs open.
Do you know what springs are on the head now?

Valve springs are
O.D= 1.260
I.D= .880
Seat Pressure
110# @ 1.7
90# @ 1.75
Open Pressure= 325# @ 1.2
Coil Bind = 1.150

When I set the head up I ended up with 1.650 plus or minus .005 some of them I had to shim a little I am not a big fan of running valve spring shims but the shop that cut the seats years ago must not have set the cutter to the same depth for all the seats. The other part of that is it throws your valve train geometry off a little. Some day I will have a Bridgeport mill and I will just buy the cutter and do heads myself. So it looks that cam would work with those springs but it would be close to coil bind.

I am back tracking here a little but you had asked about ring gaps a few posts ago I filed the top ring to .025 and the second ring the same I went by the rule of thumb for forced induction .006 per inch of bore. I am running a moly top and a steel second. I wonder if the ford six would benefit from low tension rings with forged pistons I remember reading an article though that much above 3500 RPM the 300 suffers from cylinder wall distortion towards the bottom of the block so I wonder if there would be sealing issues?

I stuck a bore scoop down number four tonight same thing again popped a ring land. The good news is the bore looks ok.

So I was thinking to get this motor back together using a set of Keith Black Silv-O-Lite 3141D-040 available at summit they have a steel insert on the top ring land which seems to be the problem area. The crower cam seems like a good way to wake the motor up and make use of the boost a little better I think with pump gas I am just going to have to keep it under 12 pounds with the water/meth. I may have to rethink what this set up is capable of even building a forged motor the amount of heat the turbo is going to generate with a draw through set up is going to be a constant problem that even forged pistons won't fix. I suppose this is a benefit to blow through that you can make use of an intercooler.

With boost the closed spring pressure needs to be higher than normal but the open spring pressure doesn't
Right now you have 130 lbs closed.
With the Crower cam the open pressure would be 340 lbs and near coil bind as you noted.
The spring rate is 430 lbs/in.

The open pressure doesn't need to be more than 300 lbs and the spring rate can be reduced to 350 lbs/in.
The closest spring that works with the present 1.650" installed height is the Howards 98412 spring and 97118 retainer.
The installed pressure would be 130 lbs @ 1.650" and 300 lbs @ .490" exhaust valve lift. (Crower 19231 cam)

The .025" ring gap is good.
In reference to piston seal, the stock pistons I have sitting here extend 1.1" inches out the bottom of the bore at BDC.

One of the benefits of custom forged pistons is to be able to get them with different ring sets and since the 300 is a 4.00" bore just about every type of ring is available.
The other advantage is to be able to use a longer connecting rod to decrease side wall loading and to have a shorter and lighter piston.

A blow through setup not only allows the use of an intercooler but the carburetor size is smaller since it only sees the engine CFM instead of the turbo inlet CFM that increases with boost.
The carburetor pressure drop in front of the turbo is eliminated which allows then same turbo to make more boost and run a lot more efficiently.

The 3141 pistons looks like a good replacement to get you back on the road.

The carburetor Power Valve vacuum reference still needs to be changed to the intake manifold.