The 352's C6AE-R heads were flowed today....

[HR427]

Thats nuts!

[chilly460]

I can’t see why anyone would not have these LR port heads cleaned up and ported even on a mild combo, huge flow gains are just too straightforward.  Even in a cruiser, you could cam down and hit the same HP goal, and there’s zero drawback (besides cost).  I think they’re one of the great “deals” out there, $100 heads available all over the place, and can support 600hp if you really turn up the wick. 

Took a little horse trading but I have just right at $1000 in my C1s, fully rebuilt with new guides, Ferrea  valves, PAC springs/locks/retainers, flowed on a bench, and they’ll blow away a set of Edelbrocks with much better machine work and components.  I think these castings are perfect for sneaky 428-462ci builds that aren’t looking to wring every last bit of power out of a combo, or looking to save $1k over a set of TFS. 

[wowens]

How about good port & chamber pics when you get them back.
This thread is great.

[blykins]

Some before and afters from Joe...

[dozz302]

I wonder how much the 5/16" stem is a factor?

[blykins]

Joe can post up some data there. 

Even if they didn't do anything for flow, they sure make the valve light.

[wowens]

Purty! The chamber work should also help with detonation.
Great job Joe!

[Joe-JDC]

I did not take a lot of material out of the combustion chambers because I wanted to keep the compression close for Brent.  Those heads have been milled a lot, and I tried to keep from having to mill them any more to retain a specific compression ratio.  I have seen race engines locally with iron heads that did not benefit from polishing the combustion chambers, and actually ran better with a rough chamber.  As to the smaller valve stems, when I flowed the same heads with 11/32" straight stems, pro flow stems, 5/16" stems, there was only ~3-4 cfm difference and that at higher lift points.  It is almost immeasurable if you don't complete this the same day under same circumstances.  I have found different valve angles and seat angles will skew the flow more than valve stem sizes.  On Brent's heads, I cut the intake valve guides down ~.050" into the iron, and tapered the guides to help take turbulence out of the port.  It seemed to help a little at higher lifts, was quieter on the bench,  and kept increasing flow as the lift went higher. The throat diameters are still a tad smaller than the 88-89% some folks want in a valve job.  I was able to get 5 angles on these seats, but the 15* top cut blended out with the combustion chamber work.   A set of larger valves and a good 5-7 angle valve job and these heads should flow ~300 cfm.  Joe-JDC   

[blykins]

Those heads have been milled a lot....

 

[KsHighboy]

Those are purty and I don't even know anything about porting! Interested to see what the gain will be. Fun topic.

[chilly460]

Joe’s got a steady hand for sure, finish and nice straight walls, that isn’t easy.  Very nice.

[RJP]

I did not take a lot of material out of the combustion chambers because I wanted to keep the compression close for Brent.  Those heads have been milled a lot, and I tried to keep from having to mill them any more to retain a specific compression ratio.  I have seen race engines locally with iron heads that did not benefit from polishing the combustion chambers, and actually ran better with a rough chamber.  As to the smaller valve stems, when I flowed the same heads with 11/32" straight stems, pro flow stems, 5/16" stems, there was only ~3-4 cfm difference and that at higher lift points.  It is almost immeasurable if you don't complete this the same day under same circumstances.  I have found different valve angles and seat angles will skew the flow more than valve stem sizes.  On Brent's heads, I cut the intake valve guides down ~.050" into the iron, and tapered the guides to help take turbulence out of the port.  It seemed to help a little at higher lifts, was quieter on the bench,  and kept increasing flow as the lift went higher. The throat diameters are still a tad smaller than the 88-89% some folks want in a valve job.  I was able to get 5 angles on these seats, but the 15* top cut blended out with the combustion chamber work.   A set of larger valves and a good 5-7 angle valve job and these heads should flow ~300 cfm.  Joe-JDC   

What angles do you use to make up a 6-7 angle seat/throat? I've used a 5 angle for years using the typical 75-60-45-30-15 deg seat. Thanks for any help you can provide.

[Joe-JDC]

A lot of guys are experimenting with seats at 47*, 50*, 52*,  55*, and throat of even up to 80* with top angles of 32*, 20* etc.  There are also radius cutters with a seat angle only.  Gets crazy when the seats are 1* different than the valve angles.  I just got two new cutters with 31* and 46* for an interference seat fit where you just "ping" the intake valve to assure it seats all the way around.   Joe-JDC

[GerryP]

What burrs are you using, Joe?  What about sanding rolls;  any grit progression?

[frnkeore]

It's my understanding that the 50° and higher seat angles, give better high lift flow, at the expense of low lift. Some porters, at least, in part, do that to keep from loosing as much of the intake charge out the Ex with large over lap's. Some use 40° seats to encourage low lift flow, also.

Besides the 32° & 20°, top cuts, I've also seen 27° or 28°, too.

I've studied aerodynamics and from that stand point, you don't want angles of more than 12°, in general, as that's where stall starts.