Porting On A 1.3

[toyota_ae71]

gday decided to try porting my own head coz i got this free spares car so i thought i would at least try!! but was wondering if i ported it how do i get a new intake/exhaust gasket that fits over the holes???

[KE30_KE35_KE55]

some brand gaskets have larger holes, check at your parts store they should have a catalouge with sizes ect.

make sure it is a nice and smooth flowing surface or else your wasting your time.

[kangaroosa]

You would only want to make the ports as big as a bigport openings (about 31-32mm Intake from memory). So just get a big port gasket and mark the head accordingly. The idea is to make the ports as straight as possible, not make them a larger diameter (larger than a bigport anyway).

It is pointless going bigger in diameter, because most aftermarket manifolds are matched to the bigport specs anyway.

Notice how you can see into the port, and out of the Valve. Standard heads have a huge rollercoaster dip from the port opening to the valve.

Edited September 23, 2007 by kangaroosa

[toyota_ae71]

kool just went and measured mine and they are about 26-27mm, so just grind out the right amount out of that then i'd have to match port the intake manifold to rite???

[snot35]

I wouldn't ditch the rollercoaster dip, try and turn it into as gentle a turn as possible. Porting will be hard to do right without a flow bench or similar. If you've got an aftermarket manifold and a better carb then match the manifold to the ports. If you want to go further there are a few steps in both the intake and exhaust ports where the port turns onto the top of the valve, smooth these into as big a radius as you can but don't get rid of everything. You don't want to lower the floor of the port. If you've got huge valve guides like most replacements are, then thin these down, and you could probably take some material from the surrounded boss. You also don't want to remove material from from the wall of the port next to the exhaust port, this will hurt swirl if you get carried away. Get a three angle valve job as well, and once it's all done, get your carb rejetted.

 

Shouldn't be too hard to find a larger gasket, some of the earlier cars had larger ports.

Edited October 4, 2007 by snot35