Eddie head porting

[Andrew]

Just had some Eddie Rpm Perf heads cleaned up by a local speed shop for a 69 440 bored 50 over w/ solid cam .540/.558, 10.25:1 compr. When I asked if gasket mattching the ports would help me get more out of the motor, they told me a gasket match on the intake side only but not the exhaust side. Anyone know why?

 

[dantrap]

From the WEB,Porting and gas flowing engine heads.Porting an engine

The inlet and outlet ports on the engine block are usually larger than those of the manifolds that connect to them.

This allows for scope in the manufacturing process to allow for mismatched alignment.

Generally the engine ports are larger in the upstream flow direction avoiding turbulance but power gains can be made by matching these up.

Most internal surfaces are far from smooth due to the casting process so small gains are there to be had by smoothing out the rough edges although polishing the insides offers little if any extra gain. Engines need to breathe as freely as possible and obstructions, seams and pits cause turbulence and this is not very good for airflow.

Generally speaking most standard non performance cars will benefit greatly from even a little DIY head porting. A high performance engine usually comes with a fairly optimum flow and these can only be improved by a specialist wich a proper flow bench. (The S2000 is a good example of this anomaly.)

The air intake port would not benefit much by opening up to match the intake manifold, unless there is a step that obstructs the airflow into the engine. So most DIY port matching work is best performed on the exhaust ports.

It is worth noting that enlarging the port size is not always beneficial and is only required in highly tuned engines where the port size has become a bottleneck. Often better flow rates are achieved with slightly narrower channels and fewer bends or angles.

A word of caution though if you enlarge the exhaust port fully to the size of the gasket when the manifold port opening is smaller than the gasket you will completely mess up the airflow. This will lose power - the aim here should be to get the two port openings to roughly the same size avoiding turbulance on the exhaust side.

This picture shows the aim of getting a smooth join between the manifold (x) and the engine port (y) in a highly tuned rally car engine.

The Fuel injector (f) indicates the limit to intake manifold polishing. A rough surface after the injector will help with fuel atomisation due to the greater surface area.

Ideally you want the intake directly above the cylinder but this is not possible due to valves and spark plugs and cam assemblies.

Many manufacturers take the intake through a 90 degree bend into the cylinder. The straighter you can make the intake path the better it will be.

Additionally the intake side of the head will benefit if you can create a Spiral flow into the cylinder as this gives much better fuel atomisation. Careful work around the valve can help with this further.

TorqueCars members have done a satifactory job on their heads but a specialist really has so much more to offer. Really, as far as a DIY approach goes, do little more with the ports and manifolds than a smoothing up and polishing (the intake manifold has the job of assisting with vapourising the fuel and benefits from a pitted rough surface so please do not polish the intake manifold downstream of the fuel injectors marked f in fig1!).
Maximum airflow can only be achieved by a specialist using an air flow bench and the very latest fully programmed milling machines.

Air flows in a similar way to water, the faster the air moves the more gloopy and sticky it behaves. If you have ever hit the surface of water at speed you will realise that it is not soft and liquid!

The aim in the head is to get as much air and fuel mixed as effectively as possible into the combustion chamber. The most important area within the engine, as far as air flow is concerned, is the valve seats and bigger power gains can be has here especially for engines with slightly higher lift valves with some careful blending below the valve seat insert to remove the steps and grooves.

 

[rumblefish360]

Yep, mostly due to the intake charge having a clean clear unobstucted shot to the valve. No turbulance from hitting a wall. (Head)

On the exhaust side, most header manufactures shape the flanges as the same shape as the port. Gains through port matching the exhaust are minimal. Best spot to do any matching would be the roof and walls, not the floor on ethier intake and exhaust.

 

[dantrap]

That last posting was a general BS on porting. If you open the Exhaust to much on an Eddy head or a Chrysler casting you loose flow velocity. If you loose the velocity or disrupt the flow the cylinders do not get cleaned out and you make less power. Also on I know on a stock head if you open up the base or lower edge of the port you can get into the water passages. I learned the hard way. Let us know how you make out.

 

[Andrew]

The heads already look really clean inside- no visible slag or imperfections except some real minor imperfections on the exhaust side which look easy enough to smooth out. I can't imagine that having any real impact on performance but I will do it anyway. I will try to post a picture in the near future. Thanks for the replies.

 

[dantrap]

Andrew i have a ported set and they were just touched close to the Ex valve (blended) and had a small amount of smoothing. No major size changes.

 

[Andrew]

The Heads in Question:

These are the heads. Upon further inspection, it seems there are some minor steps and somewhat sharp angles and rough spots left from the manufacturing process. It hardly seems that smoothing these out will change the flow characteristics much. But since I have more time on my hands than money, I will grind them smooth. I really dont have the experience or measuring tools to start messing with the the bowls and runners. I'll post some progress pics later.

Any feedback is apreciated.

 

[Meep-Meep]

I'd just do what Dantrap says and blend it all in.

 

[Andrew]

Here is a shot after.

This is a shot after some smoothing with a grinding stone. I will do some more clean up. I am trying to be very conservative and not narrow any walls- just taking down anything that feels "lumpy". If anyone out there has experience with this, please let me know if I have the gereral idea or am I wasting my time???????

 

[Meep-Meep]

Using a stone on aluminum is not that good because it just gets clogged. Get a cutter with 2 or 4 flutes (not a burr bit). Otherwise I'd say the blending looks good.

 

[Andrew]

You are right on the money, I'll pick some up tomorrow.

 

[dantrap]

Andrew they seem to be cleaning up nice. You should be able to get a better surface finish with a cutter. You might want to put them apart and glass bead the Ex. when your done, make sure you protect the seats with tape. We are luck to have a guy with a process called Liquid hone up here. It's a blast cabnet that uses a stream of hi-pressure water with media in it. Normal use is industrial metal cleaning but it leaves a super nice finish on aluminum. external cleaning is great but we have him do our exhaust ports also. Take your time and good luck.

 

[rumblefish360]

That last posting was a general BS on porting.

My post!?

 

[dantrap]

No, my response. It was an few bulleted points on head porting.