have an aluminum intake that i cracked open for cleaning. looking at it, seems that there's a lot of room for improvement in cleaning up casting flash, and polishing. but, should i go further? do more? here's some of the flash:
20230413_065124 by Michael Crawford, on Flickr
20230413_065129 by Michael Crawford, on Flickr
20230413_065218 by Michael Crawford, on Flickr
what about cleaning up right behind the throttle body?
20230413_065143 by Michael Crawford, on Flickr
anything else i should think about?
what about the injectors? on the stock intake, the injectors are divorced, just like the aftermarket intake. would blending it be worthwhile on the aluminum?
20230411_070452 by Michael Crawford, on Flickr
20230411_070512 by Michael Crawford, on Flickr
Oldeskewltoy to the courtesy phone...
argh... hate it when I write stuff and go to post it, and it seems to think I didn't post it..... BS........
Ok, to answer a 2nd time (hopefully the site doesn't fall off the flat earth......)
Blend, Blend, blend.... sharp edges cause eddys, and eddys can affect air flow. I'd use some sanding rolls, and 1/8" shafted flap wheel.
As far as the intake.... I know many of the V8s have multiple versions (typically size of port) gaskets. I'd pick the gasket that best fits the head, and then transfer to the intake if changes are needed.
As far as blending the throttle body part of the intake manifold - yes. Here is a Miata intake with a Skunk2 Throttle body fitted - before and after blending
As far as your specific manifold... I'd provide ample radii in the locations indicated... (others if similar and are hidden from this view)
The throttle body I have is actually smaller than the inlet for the throttle body in the intake manifold. However on the back side of that Inlet there are some rather sharp edges to where it goes into the plenum of the intake. Would I round and smooth those edges as well as all the backside edges throughout the plenum? And I'm not following what your meaning about the intake gaskets. Are you talking Port matching or are you talking about where the injectors are buried up in that hole?
Dusterbd13-michael said:
The throttle body I have is actually smaller than the inlet for the throttle body in the intake manifold. However on the back side of that Inlet there are some rather sharp edges to where it goes into the plenum of the intake. Would I round and smooth those edges as well as all the backside edges throughout the plenum? And I'm not following what your meaning about the intake gaskets. Are you talking Port matching or are you talking about where the injectors are buried up in that hole?
manifold porting is an art of it's own.... I've been following a few Fb groups with far more experienced porters then myself. It is not uncommon for a manifold porter to cut apart a brand new manifold to properly shape each of the 8 intake runners, and then weld, and grind smooth to show no outer evidence of it being cut apart..........
With that said... blend away as many of the sharp edges as you can without going to crazy. Air flow prefers "soft" edges/radius(look at each air intake inside thee manifold they are cast with a gently curve.... but casting is an inaccurate process, so make it look as if it had been cast without flaw.
I was talking about "gasket matching" (I'm not a fan of this) I'd look for a gasket that fits your head the best - because opening up a head(at the manifold flange), and opening up the manifold similarly - often creates an area where the intake charge slows - port goes from one shape/volume to a larger shape/volume, then back to the original shape/volume. Ideally there is a gasket that fits both your head, and your manifold with no alteration.
As far as your injector ports they look similar to mine from the hemi....
For the injectors, can you install one and look at it?
Also think about the surface it will spray onto.
In reply to Robbie (Forum Supporter) :
Is there a way to rig up an injector on the bench to test and see? I have a spare head i could bolt to and knock the intake valve out of as well....
Robbie (Forum Supporter) said:
Also think about the surface it will spray onto.
Most (not all) injectors in that general location would be spraying @ the back of the intake valve.
Agreed, I was mostly just thinking to install the injector in the head to see how much it sticks out. May give clues to how best to shape the area around it.
And the head port (where the injector sprays) will have a big impact on the airflow at the injector too, so just recommending that it is considered when designing the intake porting around the injector.
theres a rather large (relatively speaking) ledge aroung the curved side of the port. Its fairly consistent on every port at the same place. Should i take this ledge out, or just do what i did here and smooth the radius without enlarging the opening?
TOO said that sharp edges at the exit of a runner do not hurt forward flow very much but they do a great job of hurting backwards flow, and I am inclined to agree with him. He would deliberately have a .060" or so mismatch at the flanges for this reason, and his engines seemed to do well enough 
Carburetor manifold rotary primary intake ports are something crazy like 3/4" shorter in height than the intake port in the engine. What people find is that if they open up the port in the manifold to the same size as the port in the head, forward flow decreases because now the port is trying to change cross sectional area where it turns, and the difference in length between the long side and short side goes up a lot, causing a lot of funky eddy issues in the manifold. And without the sharp step, reversion increases, helped along by the loss of velocity in the manifold.
What I am getting at is, I would be completely unconcerned with the way the injectors meet the ports or any sharp steps where the throttle body meets the plenum, as long as the forward moving airflow doesn't run into them.
Those flashing rings at the runner inlets make my blood itch!!
