More from Steven Magnotti.

 

Thanks for posting more. Vizard doesn't like widening the pinch point....oh well. Too late. I was only able to get the CSA of the pinch point up to 2.0" when the wall got as thin as my comfort level (~1/16"). I think on a 400, I need not worry about velocity and tq. Ha ha ha.

I was surprised how long it took to do the pinch point...and get it blended smoothly before/after the cut. It was more tedious than it at first, appears.

I already laid back and blended the ridges outside the valves, that's done. I think I'm in about as good a shape as I can get w/the stock valves....once I get a proper valve job done. Just need to do two more pinch points on this first head.....then do it all over again, on the second head.

 

Welp.. I'm done....DOOONE, with one head. Time to start the next. Sure was hoping that I could find a flow bench for a before and after, but not in UT, I guess.

Look at this junk....

 

That is crazy! The ZZ4 113 heads were far, far, far cleaner castings that that. It is a miracle that tired L98 in your Kart made the kind of HP and TQ it did especially the power it had with the SuperRam.

 

I totally agree. I think the way they left those bowls is NUTS!....and I also agree that I can't believe the thing hit 289/375 wheel, with those ports!

....and everything else that was "wrong" with that junk!

 

I'm not sure if that's not entirely true. I believe he's referencing, in his Vortec video, how enlarging the pushrod pinch (which I understand to be the MCSA of the port) does little if the valve diameter and throat are undersized. He hadn't IIRC, addressed the form in the bowl or the throat beforehand.
I think this is why the number one move with these 113 heads is to increase the intake valve diameter to 2.00" from 1.94". Then go for a 90% throat diameter of ~1.75". Now we're up to 2.40 in² below the seat.
If the previous throat came in at 80% of the 1.94" valve, the area is 1.89 in². Opening up the pinch will do little, or worse, if there's bottle neck below the valve seat.
Keep in mind that the ideal MCSA (in a simplified way) is a function of the bore, stroke and RPM.
This is how it's been explained to me, or rather, the wider forum audience, when having these discussions at engine building websites.
More 2 cents...or 1.46 cents CDN.

 

I don't think I've ever seen anything quite like that.

 

Yup, seen a few sets just as bad..

 

Nuts! I can't believe you don't hear more about it on the 'Vette forums...or where ever. I mean...that has GOT to be some low hanging fruit right there!