head porting

I know that a lot of guys get carried away with removing material. Bigger is not always better. If you are doing a monster, that you are already putting so much money and time into. Than start with a 83/84 GPZ head and just do a very good cleanup. It will most likely get you quite a bit farther than starting with a pre-81 head. Her's my example.

This is only a slight bit more than a clean up. I just matched the boots to the carburetors than matched the head ports to the enlarged individual boots. The trick is to only clean the center section of the port, to retain good velocity. This is a view from the other side.

If you are going to fill in material. than I find "Smooth-on" Metal-Set" to be the best. We used it in the military to hold together F-4 Phantoms. I used it to make a patch on a side cover which I ground a 1/2 hole in and it held for decades. It is designed for Hi-temp use and is also designed for use on Aluminum. Look it up on their web-sight.

i ran this head on one of my 13:1 1170 motors years ago,then i had it on the 1197 in my z1 for a while too.not sure what its going on this time around,needs guides and valve job.ive never had a flowbench to use,learned everything the hard way! :laugh:

i may be totally screwed in the head but the d shaped exhuast port like a bigblock chevy still makes the most sense to me.i try to think of it in plumbing terms the short end of port doesnt need to move as fast while the long side needs more velocity to catch up .on the intake side i try not to get to big and keep port a little rough .the bowl area under the seat is what always kicks my ass i screwed up more heads than i want to remember trying to figure that area out :S

This is my exhaust side. You can see the finished port on the right and an unfinished port on the left.

PLUMMEN wrote:

i may be totally screwed in the head but the d shaped exhuast port like a bigblock chevy still makes the most sense to me.i try to think of it in plumbing terms the short end of port doesnt need to move as fast while the long side needs more velocity to catch up .on the intake side i try not to get to big and keep port a little rough .the bowl area under the seat is what always kicks my ass i screwed up more heads than i want to remember trying to figure that area out :S

Thats way too much left side of the brain stuff for me...I'll just pay somebody and save myself a whol lot of time money and what hair I have left...glad you guys know what your doin'

otakar wrote:

This is my exhaust side. You can see the finished port on the right and an unfinished port on the left.

are you keeping the ports smaller then the i.d of your exhuast gaskets?

irishwill wrote:

PLUMMEN wrote:

i may be totally screwed in the head but the d shaped exhuast port like a bigblock chevy still makes the most sense to me.i try to think of it in plumbing terms the short end of port doesnt need to move as fast while the long side needs more velocity to catch up .on the intake side i try not to get to big and keep port a little rough .the bowl area under the seat is what always kicks my ass i screwed up more heads than i want to remember trying to figure that area out :S

Thats way too much left side of the brain stuff for me...I'll just pay somebody and save myself a whol lot of time money and what hair I have left...glad you guys know what your doin'

now thats funny,youre so far ahead of me when it comes to skills it makes my head spin! :laugh:

I don't have a whole lot of experience porting heads but I'd really like to get into it. I have a few spare 650 heads I'd like to try some stuff out on. I've read alot about the theory and have a pretty good grasp on it. My question is what kind of stone or burr do you guys use for your porting?? Does APE make any shorty valve guides for 650 heads?? I'm starting to gather parts for an 810 motor and I'm wondering if GPz 750, KZ750, or KZ650 heads will make the best starting point?? Any answer would be awesome.

Stock for stock, the gpz head is better, but i bet with a little porting, the 750 head could easily surpass the gpz head.

you end up using all kinds of carbide cutters and lots of different sized stons flapper wheels cartridge rolls i use air die grinders i have 4 that are rigged up with different tools so i just grab the next one i need with out having to change bits i have a foredom cable drive set up with two power heads and lots of dremel stuff it is a substatial lay out of cash just to get set up i buy boxes of cartridge rolls by the hundred ,rolls and rolls of different grades of emory cloth, i buy cutters from snap-on i have 6 diferent 6 inch long carbides from them they are about a hundred a piece up here you have to get special alumunium cutters i have probably 3 to 4000 inveseted in seat cutters alone maybe more all together i have never put an actual dollar figure on it but i'm probably up around 10-12000 in total for every thing and i still don't have my own flow bench yet so i'll have to save up for that yet to and one also i have a special oven for doing guide replacements and a bunch of guide drivers and reamers to do that messy job as well you have a tough tim,e porting anything radical with the guides still in. it take alot of practice and alot of time bent over a bench with the air screaming in your ears to get good. i am glad i can do it but it really is time consuming and hard on your ears and back.