motomech2

Hey guys,
So today I pulled the head off my new 1.8 motor just to take a look and put in a new head gasket. Then my buddy said lets port this thing. After looking at it for a little bit I realized there is a lot of room for improvement in there. So I was wondering if any of you guys had any picks of your porting job to give me some ideas of how far to go with it. Now i'm not making a killer motor just wanna make it right the first I am installing a t25 on this build also if that'll make and difference in the advice. thanks Seth

18psi

iTrader: (76)

Just curious: do you know what you're doing when it comes to porting? Not bashing on you in any way, but if you've never ported things before and just want to go at the 1.8 head with a grinder and "hope" it flows better you're going to mess stuff up.

If you know the how/what then proceed and good luck.

Uncle Arthur

Do a search for Hakuna Miata around the interwebs and he has some useful pics/process pages for doing a port/polish job.....

I've recently had to do a head gasket replacement and I simply took the time to smooth off all the casting marks and ridges in the intake and exhaust ports - just using a light dremel stone to take the rough stuff off, and 800 and 122 emery paper and my finger to smooth it - I didn't go near the valve stems, nor around the combustion chamber - just the runners.

Braineack

iTrader: (62)

How it started:

miata2fast

iTrader: (2)

I will post pics of my 94 head that I removed to put a 99 head on. It will be for sale by the way.

Most of the material that you remove should be towards the top of the runners. Never remove significant material from the bottom of the runner. You only want to remove just enough to make it smooth. If you notice, the reason a 99 works so well, is because the runner is raised much higher than the older head. The air flow mixture does not have to turn so abruptly in the raised runner. If you take material from the bottom, the head will flow worse than what you started with.

Be careful. Most people get a head of any kind from a junk yard and practice. You want to make a mistake on a boat anchor peice of ****, and not on the head you will be running.

neogenesis2004

iTrader: (12)

I agree with you that you do not want to make the bottom of the port "lower", but I disagree 100% that you do not want to remove material from the bottom of the port. Ideally you would be able to do something like what I have done in the pic below (to the head that I ported). This would maintain the same profile but increase the flow and velocity as it tapers back toward the bowl and the short side radius. Unfortunately, you can't do this in a miata head because the material is too thin and you will cut right into the water jacket.

miata2fast

iTrader: (2)

I would call that the sides. And yes I should have stated "top and sides".

You have to take some off the bottom to get the port smooth, but take the minimun, and if it is ported correctly, the port would be raised slightly. Now where the head starts to make a turn, some material would be removed. In other words, where the cylinder head meets the intake, the minimun amount would be removed from the bottom, therefore decreasing the angle in which the air flow would have to turn.

Some engine builders epoxy the floor of some heads, to get an even higher port and reduced angle.

motomech2

well I worked on the first cylinder today but still 3 more to go had my boss who is and experienced in motorcycle porting and polishing help me out if I might say so myself it looks pretty badass but I guess we will see once I put it all together. oh yea I know it looks kinda ruff I still gotta go in with the emry cloth and smooth it all out