Small piece of clay can go a long way

[larrycavan]

I was probing an intake port similar to the one in this photo. The air just didn't want to go to the left side at the SSR. I noticed every time I put the J bend pitot just inside the port at the entrance on the bottom right corner where the rubber intake manifold bolts up and turned it just right, the port quieted down and the CFM jumped by 10.

I put a small piece of clay in that spot and formed it to turn the air left as it entered the port. Fiddling with the shape I was able to substantially raise the CFM and get the air flowing across the full width of the SSR.

The point being.....don't every take upstream shapes for granted. It's ALL relative to any given port and shape most definitely plays into the picture.

2013-04-19 15.25.14.jpg

[jfholm]

found this same thing in almost the same spot on a 2l Pinto head. Happen to put my finger in front of the port in almost exactly the same spot as you have marked on this head and got the same results you mentioned. Added a little metal tab in that spot when we put the intake gaskets on and it really helped.

John

[ivanhoew]

nice job larry,

I wish I had the same .... on a a series 5 port mini head i put my finger just inside the port entrance pointing into the port ,and got a jump of 7 cfm,so thought hmm a little bit of clay in there will help ,

but no.. it made things worse ... in the end after a fair bit of faffing about I found that what was helping was me affecting the area BEFORE the port. so I will have to make an inlet manifold that replicates the best experiment ,which was a pair of pencils side by side extending out from the floor of the port entrance about 6 inches ...flow went from 126 to 133+!

regards
robert

[larrycavan]

nice job larry,

I wish I had the same .... on a a series 5 port mini head i put my finger just inside the port entrance pointing into the port ,and got a jump of 7 cfm,so thought hmm a little bit of clay in there will help ,

but no.. it made things worse ... in the end after a fair bit of faffing about I found that what was helping was me affecting the area BEFORE the port. so I will have to make an inlet manifold that replicates the best experiment ,which was a pair of pencils side by side extending out from the floor of the port entrance about 6 inches ...flow went from 126 to 133+!

regards
robert

Post up a pic of that...love to see it.

[ivanhoew]

will do larry , im in Vancouver at the mo but when I get back ill take a pic to show you .

[larrycavan]

Here's that head I was working on....After the valve job it behaved differently.... Ignore the Velocity and CSA numbers...I didn't have the pitot in the port when I took the pics.

@.455 lift [cam is .460 on the intake side . Stock is 82@10" with 38/32.5 now 38.6/33

GPz11-at-455lift.jpg

@.500 lift

GPz11-at-500lift.jpg

PART_1398296418035.jpg

Pipe Max data PDF attached

[Malvin]

Very nice work Larry

How are you getting your aluminum heads to look as if the are brand new ??

Are using soda blasting ??

[larrycavan]

Glass bead. Real beads though...not crushed glass that most places sell.