New tech article: "How to port your own heads" -lots of pic'

[vwmorten]

here: http://www.gearheads.dk/portingside/porting.htm




please put comments and questions here..!

Best regards

VWMorten

[This message has been edited by vwmorten (edited 12-04-2001).]

[Joe Boone]

Nice Job.
A few of the first pictures won't enlarge.

[74EMPI]

Would following the steps in this article help much with stock heads on a 1776 with 34 webers?

[itsbuggytime]

nice job, so you did this with the valve guides in? Later perhaps explain how to get the guides out and grind the area where the valve guide hole is on the intakes. Alot of flow can be had here. Also, if you go to the dremel section at wal-mart there are very small flapper wheels that sell for like 5 buck a pop!. Get about 1 per intake port and give them a try, along with wd40 they smooth out the port REALLY WELL.

[calereeves]

AWESOME! good job man, I've got a spare set of heads at my house that I was thinking of doing this to, but kinda wasn't sure where to take the material from...i'll try this in a couple of weeks, and see how mine turns out. Have you ever ported heads before this one?

Cale

[mike75bug]

What is "lapping" valves. Pardon my ignorance.

[sparkmaster1]

You lap the valves by having the heads apart and put a small amount of an abrasive on the valve where it rides on the seat and turning it back and forth ( at least 360 degrees) until it seems smooth. KInd of like trying to start a fire with a stick. I use a piece of fuel hose on the valve stem and use a light, pulling pressure. You also want to keep the valves in the same hole after you are done. I personally use a silicon carbine grease that is a 150 grit. It makes the seal between the valve and the valve seat more precise. It also will show you exactly where the valve face is riding on the seat. You can also use a bluing compound for this. I agree with John on the amount of material that was taken out of the combustion chamber, it semed like way too much. Also what is everyone else's feelings not polishing the chamber? I always try to polish the chamber, and exhaust ports as much as possible and finish off the intakes with a ball hone for a swirl effect. Tim

[This message has been edited by sparkmaster1 (edited 12-05-2001).]

[itsbuggytime]

Polishing chamber/exhaust does help, but spending all that time on it doesn't get you a whole lot of improvement. Just my opinion.

[JohnConnolly]

WAY too much material removed in the chamber (he went way overboard on the "valve unshrouding"). Some of where it's removed hurts flow a LOT (check the How to Hotrod book for details).

John
Aircooled.Net Inc

[tarnx]

Nice article VW Morton. I plan on porting my heads in the next two weeks. I will have some major differences due to my needs.
First I will be using single port heads as I am going for high velocity at low engine speeds. The local dune buggy guys tell me you get better low end out of the SP heads. The intake port will be sized to the intake valve port to match velocity and the exhaust tubing will be matched to the exhaust port also to maintain velocity. Apparently in my readings on the subject there is minimal loss of velocity in a curved tube so long as the cross sectional area remains the same. I am taking this theory to the internals of the head and I am going to try to maintain the cross sectional area from intake port to valve port and exhaust valve port to exhaust. Note it is the valve port size we are matching and not the valve size.
Any protrusions into the air stream such as casting marks can cause turbulence, flow reversion, and other nasty things. They will just be smoothed down to the surface. Any lips will be recontoured or removed depending on if I can determine if there is meat behind them to allow it. A general smoothing is the main idea.
The intake and exhaust ports will be match ported to the intake manifold and exhaust header. VW Morten showed how to do this quite well.
A three angle valve job of 30, 60, 90 degrees aids the flow through the valve seat. The 30 and 90 angles will be blended into the head surfaces. The 60* angle is where the seat and valve mate. The width affects flow. Racers used to narrow the width to improve flow. Since this is a street engine I would like to keep it reliable so the width of the 60* contact surface will remain close to stock. The exhaust valve head gets most of its cooling from contact with the head. A note make sure the width of the 60* is the same on the valve and the seat and they match up.
Some racers taper the end of the valve guide where it sticks into the head to improve flow. Here again I will go stock for reliability.
The surface texture is an ongoing debate between polished and rough. The NASCAR guys use both depending on the fellow who built the motor. Polished is supposed to give better flow at high RPMs makes sense. Rough is supposed to tumble any fuel that drops out of the air flow causing it to recombine. This also makes sense. Any way I will be using a 120 grit finish on the intakes as I want to keep a uniform air fuel mixture at low velocities. The exhausts will be polished to maximize the exhaust velocity and get it out of Dodge. In my aerodynamics book the author states that the air molecules in contact with the surface aren't even moving no matter how fast the air flow. Yet he goes on to say if you wax your car it will go faster. Go figure.
As far as the chamber is concerned if I cleaned it out as much as VW Morten did I would have no compression left. Since I will be using 1500 pistons with a 74 mm stroke I will need only small changes to the chambers. The plan here is to adjust the compression and chamber volumn to what I need just by breaking the edges and unshrouding where the valves are most perpendicular to the head. Any lumps or bumps which could heat up and cause detonation will be smoothed down.
I suppose what I am doing could be considered blue printing the head as opposed to the traditional Port and Polish for improved flow. I might only gain a HP or two, but that is more than I had and with the ten other 1 hp gains from little things, the little things start to add up.
Vw Morton left in an old set of valve guides and valves to protect the areas while he was working on those areas. You could also cut off the top of a cylinder about a 1/2 inch high to protect the cylinder mating area against grinder run away. A double layer of duct tape is also good. I have used die grinders extensively and they will get away from you sooner or later. The steel burrs and stones bounce around pretty bad if not held just right. Rubber wheels with sanding drums, craytex rudder grit wheels and flapper wheels are excellent.
In review this is what I am going to do. It is my opinion based on research and my needs, and I am sticking with it.

[Tom Simpson]

I would agree that the chambers are opend up too much. Also, flapwheels are great for smoothing out the finish real nice. They work fast and last a long time. I like to thin and profile the exh guide boss as well for improved flow. Your work is good for roughing out the general shapes, but I personally believe that you should take more time to get the finer details smoothed out and shaped exactly like you want. I spend 15-20hrs porting a set of heads in similar fashion. I'm not bashing your work here, just adding some constructive critisizm... I did a set of stock heads this way. Put them on a 1585cc motor and ran 15.38 1/4mi. Engine pulled to 6,700rpm. Upped the disp to 1755cc and ran 15.1. Installed some 40X35.5 valved heads with same port job and runs 14.40's... I like your "poor man's" valve job. I do exactly the same thing to my valves. It takes a real steady hand and some Kahoonas....

[petevw]

what do you guys think of these?
superflows with 48x38

[Steve Arndt]

A few shots of my little 044 heads.

[Steve Arndt]

more

[mikeb]

Steve, glad you included the "Welded" photo. I was begining to wonder how well that porting was going to work after seeing the first picture of the manifold.