but when you flow and make ports bigger, the manifold does not change???so based on that you still see results, yes i may see a little result but getting to the point of people finding it hard to tune with itb is another key element, as i have been advise from rxi18675 turners find it more easy to turn without itb,and the whole story of vacuum being to less,there are factors that i thought of first

[quote="rxi18675"
Well i havent seen the 16v head so not to sure of how big the valves are... But it has to do with positioning. will take pics of the pocketed Gze piston and post later!! think also the 20v cams do have more lift than the 16v [/quote]

If anything the valves are bigger and/or it has more lift, but they should sit in the same positions. Would be worth while to measure up an example of both to confirm this.

Ok it seems the 16V has 25.5mm exhaust where the 20V has 26mm exhaust.

Valve angle on a 20v is also alot wider than a 16v,so positioning is different aswell!!

cost is not i big thing, worked it out, and it will cost me less to fit the 20v head then send my 16v head for a full head work

20v valves are bigger and at a different angle,read up on this some where,

small only way going around the small intake ports on the manifold is making them bigger.
i am looking at all sides, the more info i get, the more reasons to push me on the right direction

sorry did know the pic was going to come out so big.

i was going to use it for itb on a smallport head setup

ok i thought of something, the tvis mani must have been big to match its ports right?so using that will fix the narrow mani ports problem, what you think boksie?

Okay... This is simple u just complicating it more.. so much of info here we have given you.. which leads to just use a 20v head be it black or silvertop... and use the itbs small port mani ports are smaller than that of a blacktop .. how will u increase them in size? u creating a restriction..

This is the ze piston with valve cutouts for a 20v.. this is a sample piston i use... Looks more like valve angle aswell as size abit of both! ? As u see its on the outer edge of the pistons...

Also when i use blacktop pistons and 1, 7afze headgasket for higher comp pocket the blacktop pistons on the outer edge aswell on the exhaust side!! In my experience reving to 9000rpm with 0.8headgasket.. and no pockets on the exhaust side .. the exhaust valves just polish and touch ever so slightly on the pistons .. with valve springs this does not happen!!

ah ok, good info to have then!

good thing is I have had first hand experience with all this! so its solid info no speculating!