why not port/polish your own cyl heads

[muscl car]

it seems that everyone today wants to spend the extra money for aftermarket ported or cnc ported cylinder heads than to work on their own cyl heads !!! . it's not that difficult to port/polish cyl heads and even GM has a book out that shows were to grind/remove material also were to polish . i'm looking right now at a chevrolet power service manual circa 1988 and it has all the templates to properly port/polish any sbc or bbc cyl head . i've done my own cyl heads that are currently on my motor and followed this guide and it took me a weeks worth of work for ea cyl head

it wasn't that hard to do and got all the cartidge rolls,abrasive tips and cutters from summit and all ready had an electric die grinder . i'm just curious why you would spend extra money for a company to do a cyl head than for yourself working on one



the book i've got shows modifications like to the bowl areas ,removing material on the intake port floor , intake/exh port modifications and modifications/material removal in the combustion chamber

[sooner]

Got me....The words free horsepower always have had a nice ring to me and that is why I port my own heads.

[Kamikaze]

muscl,

I think you and I come from the times where people learned to make horsepower, not buy it and bolt it on!

The problem is too many people do not have the hands on skills or the guidance to direct and back them up on something we consider simple!

Also, many people are intimidated and may not have the time or can't justify the investment into the tools whereas they will spend the extra dough to just buy it done and bolt it on!

Time is a big factor for people. Some don't have it, some will find a way to make time, and others just won't bother!

[jester1]

I dont know how to answer that. I will say I wish there wer a popcorn smilie, better yet Id love to see that question on anther fourm.

I think the S1&t would hit the fan.

Ive seen people fork over 2K on a port job thinking they were getting something professionaly done. Then they get them flowed and have numbers like "oh who nees so and so head when mine flow 375cfm @ .750." A swere pipe flows the same. What the difference is if you do them in your garage your a hack but if you do them in a shop that has a fresh new sign then your a pro.

There is a difference between a clean up and a full flowed port job. This could be a two sided conversation. If a pro hacks up 20 pairs of heads before he learns what works and what doesnt hes concidered to be a pro. " so & so" did it or "thats so & so" heads on that engine. If you do that in your backyard you are a complete hack and when you get the results your looking for your still a hack. If your heads are the best heads around after your learning curve, your still a hack and "my heads are CNC'd".

[RSA'81Berlinetta]

stupid Q...I have always been familiar with the process of polishing ports. Just the other day someone mentioned to me that polishing ports is not such a good thing after all, and that a rougher surface helps to break up and atomize the fuel on intake for better combustion. Kinda makes sense.
What are your opinions on this theory?

[muscl car]

Originally Posted by RSA'81B

stupid Q...I have always been familiar with the process of polishing ports. Just the other day someone mentioned to me that polishing ports is not such a good thing after all, and that a rougher surface helps to break up and atomize the fuel on intake for better combustion. Kinda makes sense.
What are your opinions on this theory?

only ports to polish are the exh ports doing this will allow the exh gasses to move faster into the header/exh system .the intake ports you want a rough finish as you described to allow better fuel atomization

[ThumperZ28]

hey

would it be too much

to ask if you could, tell me the title of the book and author


im interested, im gona be taking Auto Machine shop next semester in college

but

i cant wait till then
...

i figure i port my Stock GM aluminum intakemanifold, and heads

and gasket match them to the heads

all the while, semi-port my heads and do a little bowl polishing

and then pay a local professional machine shop

to do that full port job..

[jester1]

Thats the general idea. Now at the same time its whats written in rag mags. Is that true or not I cant realy say. If you see the newly CNC'd head that are emerging the people that are writing the pathes are getting the tolorances closer which virtualy eliminate the tool marks. With no tooling marks the surface is smooth and not rough. If they go through that trouble why not leave the tooling marks which is rough surface to promote this turbulent effect?

A turbulent flow is not a laminar flow...

MC had no idea you werent felling good, hope you fell better.

[muscl car]

Originally Posted by ThumperZ28

hey

would it be too much

to ask if you could, tell me the title of the book and author


im interested, im gona be taking Auto Machine shop next semester in college

but

i cant wait till then
...

i figure i port my Stock GM aluminum intakemanifold, and heads

and gasket match them to the heads

all the while, semi-port my heads and do a little bowl polishing

and then pay a local professional machine shop

to do that full port job..

chevrolet power catalog 6th edition printed nov 1988 technical info by chevrolet motor division

[Kamikaze]

Thumper, I believe any of the older pre-90's Chevy Power Manuals will show you the basics. Also, the How to Hot Rod Small Block Chevy's had some diagrams on the 292 heads.
Here's a few good books to add to your library:

The Best of Hot Rod Magazine Volume 1: High Performance Chevy Small Block Cylinder Heads

The Chevrolet Racing Engine by Bill Jenkins

How to Build Max Performance Chevy Small Blocks on a Budget, by David Vizard

How to Build Horsepower, Volume 1 , by David Vizard

Power Secrets, By Smokey Yunick

[Cataldo]

Sy, I second those books, The one that Smokey Yunick wrote is worth every penny and then some.

[Simon@London]

Originally Posted by muscl car

it seems that everyone today wants to spend the extra money for aftermarket ported or cnc ported cylinder heads than to work on their own cyl heads !!! . it's not that difficult to port/polish cyl heads and even GM has a book out that shows were to grind/remove material also were to polish . i'm looking right now at a chevrolet power service manual circa 1988 and it has all the templates to properly port/polish any sbc or bbc cyl head . i've done my own cyl heads that are currently on my motor and followed this guide and it took me a weeks worth of work for ea cyl head

it wasn't that hard to do and got all the cartidge rolls,abrasive tips and cutters from summit and all ready had an electric die grinder . i'm just curious why you would spend extra money for a company to do a cyl head than for yourself working on one



the book i've got shows modifications like to the bowl areas ,removing material on the intake port floor , intake/exh port modifications and modifications/material removal in the combustion chamber

I'll answer this one......time is money my friend. I had a set of smogs done in spring time and they actually did a very good job. MY buddy races oval and we pulled them off together to install vortecs and he was impressed with the job done on those 920 smog heads. My receipt sitting here says I paid $295 for porting, springs and two valves which took them 2 days my builder in St.Kitts mentioned. I wish I had the time to learn it but that ain't happening with my job. Then come weekends I like to keep that time open to hit flea markets/ swap meets and car shows. So porting some heads would be probably on the bottom of the list and better left to a head guy for a fee.

Many car guys I also know just don't have the time to spend ripping motors apart, juggle careers, families and hit the car show circuits before winter comes back.

So to simple answer this > $$$ plus time it just makes no sense to me at least.

I make a lot more funds in two days than any simple small dollar port job would warrant me doing it myself. ( not happening but maybe after retirement )

[z28rod]

people do not have the hands on skills or the guidance to direct and back them up on something we consider simple!

DITTO

[Cardinal]

There are many different reasons why someone wouldn't "blueprint" a pair of heads.

Mine is my health issues would preclude porting a set of heads. If I did try it, it would take weeks (and possibly months) to do them and months to recover from it.

Fear of destroying a head would be another. Most factory heads have some drift in the castings. I've seen heads that should have easily had bigger valve springs put in but the casting was thin = hit water.

Tools might be another limiting factor.

And it takes time to do them. Let's face it, not everyone has hours to spend sitting at a bench grinding away on a cylinder head when you can open a catalog and buy a better set of heads for under $800 to $1200. Time is money.

[Rick WI]

Benefit cost. You can hog all you want on old castings and never get close to what a good modern cylinder head will do from a performance standpoint.

On top of that porting yourself with no real knowledge of what you are doing can just as easily loose you power (maybe moreso) than gain.