# 8V Head porting



## John Milner (Jul 20, 2005)

This is my first attempt at porting a 8V head which is a spare old corroded 8v cyl. head I've had laying around few a couple of years & thought I'd give it go.

What I'd really like is some feedback/advice or anything in regards to my test porting on a GX 8V head with standard valves. 

This is straight off the burring bits, as the cartridge rolls I ordered hadn't come in yet & was itching to have a bash at making a start on it.

I've just opened up the ports to the gasket sizes & smoothed off everything I can reach. Its all very smooth to touch with no rough spots or high/low, lumpy sections.

The reasoning for cutting & shaping the guides was, I showed the head to a local performance shop & he said due to the OHC with valve forces being fed straight down on top of the valve & not trying to be pushed to the side like a Big Block chev with rocker gear & side loading & also the bonus that there is plenty of meat on the guide boss around the guide & the guide being pretty long, I could hog it all away. Makes sense I suppose.


I don't have a small enough burr to get into the two sections in the exhaust port around the base of the guide, but it will all end up being blended by the cartridge rolls. A couple of new smaller burrs are on order too!

Its only a test port job which may be modded some more or just copied over to my current cyl. head which has already has a T3 turbo fitted. But since the current engine has some damage, the time has come to upgrade a few components, along with a larger T3/4 turbo. So I thought I'd have a bash at the head while its off & the engine is getting a rebuild over the next couple of weeks.

Pics


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## antichristonwheels (Jun 14, 2001)

it looks real nice, but only the flow bench knows for sure. It does look good


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## John Milner (Jul 20, 2005)

antichristonwheels said:


> it looks real nice, but only the flow bench knows for sure. It does look good


Cheers for that. 

I'd like to get it flowed, but can't really afford it with all the rest of the engine build going on.

Might just to flog the credit card alittle bit more! haha. 

But I think it would be interesting to see, as even though I'm happy with how they have come out for a first time & will still do alittle more blending etc. 

I have sent the pics to a local well renowned cyl. head ported & he's got a couple of tips & advice for me, which I'll use & test on this head & then port the actual engine cyl. head.

This is for my K-Jet turbo project which is getting another upgrade very shortly.


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## Str8pipingti (Oct 10, 2010)

all i saw was a little bit of out-of-round on the intakes. might want to match them up with a caliper mic and or a matched gasket set. on the other side looks GOOD for a hand done P+P!! good job!!!


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## John Milner (Jul 20, 2005)

Str8pipingti said:


> all i saw was a little bit of out-of-round on the intakes. might want to match them up with a caliper mic and or a matched gasket set. on the other side looks GOOD for a hand done P+P!! good job!!!


Thanks dude. Really appreciate it. Still haven't polished/blended it yet. Will do that once I receive the cartridge rolls & will see how it comes up. Not going for a ultra polish/shiny finish on in the ports, but will smooth off & polish the combustion chamber (head) face.

The port may look out of round & it is, as I just ported out to the gasket scribe line in which the gasket isn't totally round either.

I will definitely be using a caliper mic & other various measuring tools when copying over to the rest of the ports!


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## Str8pipingti (Oct 10, 2010)

got a pic of what tools you used to accomplish this porting job? you inspired me to try the same on a extra head i got laying around.


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## John Milner (Jul 20, 2005)

Str8pipingti said:


> got a pic of what tools you used to accomplish this porting job? you inspired me to try the same on a extra head i got laying around.


I'm just using a Blue Point 1/4 drive die grinder.

The burrs I'm using are

3/8 Cylindrical Ball Nose
3/8 Cylindrical Ball Nose long shank
3/8 Egg Shape
1/2 Egg Shape Long Shank. (I really need a 3/8 version of this to help with the short turns & its still on order)
5/16 Ball shape

Thats all of them.

I'm yet to get my finisher cartridge rolls, so the finishing will have to wait











I had more of a think about the shape of the intake ports

So I got stuck into ported the head & I started off removing the sharp quench area's & also de-shrouding the valves.

I also decided to shape the intake ports & tried my best to try & redirect the intake around the long side of the port & direct the charge into the centre of the combustion chamber to promote a swirl/well mixed charge.

I also added a nice long bump on the short/inner side of the port to promote the charge to slow down to help with both slowing down the charge so it doesn't counter act against the fast moving long side charge & also help swing around the short turn

These are pics from my build thread. This is the actual head that came off my car & will going back on. So I can't stuff it up
















































Intake (to the left is the centre of the cylinder)












Exhaust


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## Str8pipingti (Oct 10, 2010)

are you also going to undercut your valves stems?? add even more air flow to the cylinder. cant wait to see more progress! this is one of the best i have seen for a DIY. really putting the knowledge of good flow characteristics in to this. this isn't what you do for a living is it?


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## John Milner (Jul 20, 2005)

Str8pipingti said:


> are you also going to undercut your valves stems?? add even more air flow to the cylinder. cant wait to see more progress! this is one of the best i have seen for a DIY. really putting the knowledge of good flow characteristics in to this. this isn't what you do for a living is it?


G'day Str8pipingti.

I will be fitting a set of 40-42mm & 33-35mm valves on the next build & yes I will be adding a 30 degree back cut to those valves.

This head is just sort of an experiment at the moment to see how it goes. So I'm not going to have the seats recut or the guides replaced. 

Sort of like a budget build & I'm just bored & felt like having a go at something I've always been interested in, but never got the chance to get into this sort of trade.

I'm a mechanic (glorified technician as they like to say) by trade & have done it for nearly 15 years. most of that time, I've been playing with Mk1's, K-Jet & any sort of engine I can get my hands on to play with, from these cars to big block chevs.


If everything goes to plan, the next engine will be upgraded to a 1.9L, receive a new set of pistons, rods, all balanced & l'll send the head off the bloke who has been giving me some advice & I'll have all the new valves, guides, seat cuts as recommended (can't give everything away sorry as its his own thing) & he said he'll have a look at my work & give it a once over & clean up any area's that aren't up to his ultra high standard, flow test it & then send it back for me to copy the rest of the cyl's. 

I'd like this to happen sometime next year, so it will be awhile.



I have spoken to a cyl. head guru over here & he gave me a few more pointers as to where I can move further forward with this head, so I decided to give it a try on the test head first.

On a first look it does look pretty aggressive as its only a rough cut & I'm yet to see another Mk1 head ported like it, so we shall see how it goes.
The idea to try this on the test head was to see how far I could push the port floor to the short turn & turn the semi-round port face into a flat even turn across the port flow on both the intake & exhaust & yes I did break through & find water! haha

But its only a test thing.


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## John Milner (Jul 20, 2005)

Heres some updated pics of the proper head I'm using. 

I still have a couple of tiny things to blend & reshape on the guide boss', the port floor alittle bit flatter & also smooth out the radius' of the port floor to the port walls, but you get the idea. 

I'm yet to see another 8V port which is shaped like this, but happy to be shown some. 

I had some large round flap sanders which I was able to finish the port runners & bowls, but they are too large to get in & around the corners & guide boss' 

I might also reshape where the seat is pressed into the head & protrudes into the chamber. 

You can see a bit more clearly the damage to the cyl. head after it swallowed something in a previous life to when I've had it. 

Looking forward to seeing how they flow with a smaller 38mm valve compared to the big guns of VW head porting & even the eurospec heads. 

This is all for the pics for a while sorry. 

But I'll get some more once everything has been finally smoothed & blended. 

Then I'll try & flog my credit card some more to get some flow numbers to prove if all my work has been worth it. 

Hope some of you can get something out of it


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