Going through lots of parts I have laying around, decided to have these heads flowed. Searched some past 906 head threads, and these seam to be pretty good, especially considering the valve sizes



20200712_101644 by William Dewing, on Flickr

How old are those results and what type of bench?
If they where flowed on a good day, high pressure with cool temps and low humidity they may not have the same results when flowed on a hot, humid day on the same bench
The real proof is in how well they run on a motor

They were flowed 10 days ago, they are a pair of legal Superstock heads, hence the small valves. A lot of "epoxy" and work done on them.

Those flow numbers are good for a iron head, not so good when compared to a decent set of new aluminum 440 replacement heads with bigger valves
NHRA rules in SS do allow room for a lot of port work

I believe in SS the port work you are allowed is basically unlimited, but valve size is limited to .005 over stock, hence the 2.083 and 1.743 valve size, chambers and runners are limited to published numbers also

There are quite a few rules regarding what’s legal for SS, but the gist of it is...... there is a CC limit.

Those are actually pretty small at 195cc.
They’re allowed to be 203.

I freshened a set last year...... they were about 10cfm less, and were closer to 203cc.

Outside of valve size, chamber and runner cc, and the intake face not getting into the valve cover holes, I think that is basically it. These were flowed on a 4.35 bore, but the engine they were on has a 4.39 bore. I forgot to mention that to them. With these smaller valves, would the larger bore affect flow much ?

Those numbers are very similar to the 346 casting super stock heads I did for my engine.

You are about 30 cfm down from a real good set of SS legal heads.
About 17 up from a standard maxwedge head that has std. valves and ports.

The Stg 5 heads offer greater opportunity. I've had virgin Stg 3 heads on my bench, still had the studs and yellow springs and they are no where near 280 CFM at 28 inches.

I have a virgin set that are stock, flow 278. Std. valve size, 440 nail head intake valve. Same bench that flowed the SS Stage 5 SS head.

It shows 302 cfm (intake) with clay radius.
Is the 296 cfm with a radius plate or nothing?

nobody in there right mind would flow an intake port without a radius plate. it just isn't done.

My interpretation of the sheet is...... the intake port was tested with a clay radius(as opposed to a radius plate).

The 302@.650 is a “footnote”, since that lift isn’t displayed in the normal increments.

In other words, the peak flow is 302@.650 lift.

They weren't done on a Superflow with those flow ranges and it would be rare for a 300 range to be 300 on the dot, usually come up a bit below the range number so I'm guessing a calibration plate=factor isn't being used here, not a problem if you're building heads and using the machine for reference but for comparison to other machines it becomes a problem. It's the same problem with dynos that aren't calibrated.

I don’t know...... this one seems to have a flow range pretty close to 300 for the intake.

In fact...... all of the ranges used for that test on both intake and exhaust are pretty close to the ranges of the one in the pic.