I'm currently doing my own streetport. With a template it is easy to match the shape of the primary and seconardy ports openings on the face of the plates. However I'm doing a little porting on the interior walls of the intake ports to try to blend them into the larger port openings a little better.

My question, perhaps a stupid one (since I'm new to this), is if other than just using my eyes and touch how can I ensure that the porting to the intake walls is exactly matched between the ports? Or is it not that critical?

 

if you're referring to the runners, then there is a subtle venturi-type shape to them and i think it should be maintained as much as possible. i suppose if you find an accurate and reliable way block the runner right at the opening edge of the port, then you could use a fluid to measure volumes when you're done, but i usually just leave it up to my eyes and fingers.

 

Yes, intake runners... that was the word I was looking for.

I thought about the fluid volume method...

... but yeah... I think I'll take your advice and match as best I can by eye and touch

 

From what I have heard talking to someone who flows parts you would have a hard time messing up the flow balance between the ports on a 3rd gen worse than the factory lower intake manifold does

We all try to match ports as best as we can by eye and feel, but the best way would be to use a carb synchronizer or a flow bench. I polish the ports so I can see the differences better visually and then add texture back in where appropriate.

Look out for differences in the high velocity areas like the outer radius (bowl). Most common is for one port to have a good casting core shift and the other to have a poor one (leaving a lip at the oil control ring seal area).

4 port housings aren't too bad as far as casting goes, but I have seen horrible differences in 6 port housings- even in the intermediate housing (side by side ports). I have a theory this is due to the smaller cores in the 6 port casting process shifting more easily.

 

Only people I know of that use a flow bench to match their ports are Rotary Performance/Rx7.com.

Jack

 

From what I've found there's really no point in enlarging the intake runners at all. They flow plenty. Make sure the port openings are the same between sides. They need to match as close as possible. I will slowly port both primaries and then both secondaries at the same time, going back and forth to make sure I do the same thing between each one. I use my flowbench to make sure they are even but I do more than just bolt them to the bench and do a static flowtest. I do multiple tests because it will tell how well they are truly matched. I will bolt on a rotor housing and install a rotor in it as well. I test with a rotor in multiple states of port coverage and then compare the results from each port to the other one. The flowbench is not all about total flow numbers. It's a tool used for consistency.