Well it appears my motor has finally developed a nice rod knock. For my High Performance Engine class project I was going to do a 2bar tune, so now that my motor needs to be rebuilt, I'm going to porting/polishing my heads/intake instead.

I would like to get some tips or ideas from those of you who have done this. What to do, what to look out for, what tools to use, etc.
For starters I'm just going to gasket-match the 2 sides and generally clean up and smooth everything out. I'd like to start a good technical discussion. Has anyone tried adjusting the length of the intake runners inside the intake manifold or anything?

 

Be prepared for all the "you should leave it to LE or AI"


but i would like to find out how to port heads and intake as well

 

LOL there is a reason you will get the you should leave it to the pros First it takes specialty equipment which the average joe won't have access to. Second it takes years of experience which the average joe also is lacking.

What I would recommend is to get you a 6"aluminum deburing tool and get you a junk head and start working on it. After a few days you will get the drift really quick....a seasoned porter EARNS his money! It is hard and tedious work and not for anyone running short on patience. Its also a neat little trcik how they get all cylinders to MATCH!
Its one thing to hog a head out, yet another to get it to flow and swirl properly.
With that being said you can check out the standard abrasives website that gives you a little how to. Just be warned that you can mangle a head beyond repair so definitely be aware of that!

 

Honestly, I'm not the slightest bit worried.

I problably won't touch the chambers too much, except to polish them, smooth any potential 'hot spots', and even out their volumes (my buddy has a cc'ing burette)

 

By starting off with the gasket match you are already heading in the wrong direction. Once the intake and head are bolted together that will create a fat spot in the middle of the combined port causing the air to slow and then speed back up wasting energy.

 

Spend your time doing valve pocket work in addition to installing RRs, springs, etc. i.e, upgrading your valve train.

Doing some quality work on the valve pockets including radius work will prove beneficial and not as risky as actual porting the entire heads. Do some homework on the hows and tools needed. Take several ganders at heads with good pocket porting to get a good understanding of what to look for. JMHO

 

well, def. spend alot of time searching for some pics of stock castings that have been ported to get an idea what the guide should look like.
I have some pics at home I'll post for you when I get there IF I remember. lol and have time.
you'll notice right away how much the exh port floor is off compared to the gasket, so dont even think of matching that gasket. just leave the floor alone exc. for smoothing.

in general, make sure not to change the short turn radius cause its sensitive, and you can get it way wrong/worse easier then making it better. (short turn radius is between the runner, and bowl, incase you didnt know on the floor side)
most of the meterial will come out of the roof, and some out of the bowl, and whats around the guides will be very obvious once you see a few pics.
be very careful with the pushrod pinch when opening up the port on the intake side.

as for the intake, its pretty simple. raise the ports as much as you feel safe and just clean them out/square them up. up at the front, gasket match thethrottle body opening now even if your using the stock tbody cause that way its done if you decide to swap the tbody later. open the throttle blades and you'll see right away what needs to be removed there.

also, dont polish the ports. you want a rough surface to create a slight turbulance on the walls. I cant think of the term right now. so I use a medium sand paper drum to do the blending, then go back and make it rough cuase its easier to follow the reflection to see where you may not have something straight. I'll use an 80 grit drum to make it rough and consistant.
you'll need alot of diff. tools. I use a die grinder with a regulator that allows me to give it like half power/speed. that'll make the drums last longer cause they werent made to work at 20000 rpm. I think 12000 rpm is the sweet spot. you'll need 3 and 6" mandrels as well as 3 and 6" nonferous cutters in the christmas tree shape.

yes, expect to spend A TON of time doin this, and doin it over again, then doin all the other cyl.s over again. you have to keep the ports consistant from port to port. I like to do them all in stages. makeing the same cut on each cyl. then goin back and hitting another area.
if your expecting LE or AI #s, forget it. it takes alot of practice and tiem on a flow bench to get there #s. my first time around, my heads flowed 245I at .550 so I was pretty happy. Im in the middle of redoin them now since my combo is changing and will be a strip car, 383 SR with a large single plane.

 

Good info guys, thanks.

I see what you mean. would it be a good idea to remove material from the intake side so as to create a nice taper from the plenum down to the intake valve? (think velocity stack) or at least open up the runners evenly throughout?

I have also heard elsewhere to leave the runner floors alone.

 

I would look into purchasing some good literature on the small block Chevy. Books like these contain a ton of info for not a lot of money:

• Smokey Yunick - Power Secrets (wow. This got expensive!)

• How to Build Max Performance Chevy Small Blocks on a Budget

I think Vizard has a separate book on heads/valvetrain as well.

Might also see tech articles here: http://www.gofastnews.com/board/

Good Luck and consider building yourself a flowbench. As you know, working a cylinder head is an art learned from experience. To be a good porter, you really need to apprentice with a good engine builder and/or port and flow lots of heads! Never too young to start.

-Scott.

 

You'll kill the head if not done properly. This is not some myth made up by the surf's of the cylinder head God to appease him, it is simple truth.

The only way that I ever recommend a novice attempt porting if they do not have access to a flow bench and dyno to quantify results is to simply let your finger do the walking and talking in the port - if you feel a sharp edge, round it out. Smooth transitions are as good as you are going to get without the proper tools and experience.

 

intake mann. port


here's a cutaway of an LT1 port, copared to an LT4 port. just so you see what your dealing with


here's the exh. side


oh crap, dont have that file here at home. here's a pic of mine, the first time around. this is my first set of heads ever ported. mentioned in my first post.
you'll notice right away compared to your stock ports, that the stock roof is angled. you can remove most of that and make it alot flatter. I havent tried to experiment to see how far you can take it, but I made mine maybe a few degrees off from flat. didnt want to make the roof weak, and rip a rocker pedastal out. lol. Ive seen it happen in overported LS heads. I"ll try to copy the file I got of the pro-ported int/exh ports I collected over the years tomorrow.


here's my flow chart to prove it.

again, it aint the best, but it only cost me bout $100. including paying $60 for the flow test. not including the hard tools cause I still use them for all my porting Ive done. but that includes a bunch of sand paper drums.

chris

 

well, to that I say, how do you think the Pro's got started? anyone with either a large air compressor or an elect. grinder can do this, IF you take your time, do lots of research, and dont expect pro results. and your ok with poss. ruining a head or two while your learning. thats just my $.02

 

They had many heads to practice on and test results, and the proper testing equipment with direct instruction from someone who had been there/done that.

If you're fine with killing your only set of heads, and having to buy another set to start over with that's fine - I'm not discouraging people from learning on their own...just that I have literally seen hundreds of home port jobs, most of them are disastrous even with verbal instruction from the pro - there is skill and experience needed to make the tools do what you want.

 

Very true.

I intend to play with a pair of heads for my wagon, for the sedan I trust a true professional with professional training.

 

with there FIRST port job? I doubt it. Im just saying. sure your not goin to make a competive pair of heads. but can you get alot better then stock? for a fraction of what a pro port job will cost? yes you can. I did. why cant most people?

so under your theory, people on this board, shouldnt TRY to replace a cam? or rebuild an engine? cause there not profesionaly trained? and there's potential to cost yourself alot of money? apples to oranges I know, but the idea is the same.
yeah, some people wouldnt want to risk there STOCK heads, but me, and Im guesing the OP, dont mind "risking" there stock heads in order to have a good time learning and trying something new. agian, Im not suggesting someone buy some afr heads, and try to port them. were talking about heads that are worth $150 a set.
im not trying to be argumentative. you guys have made some good points. but I just dont believe people should be bashed into not trying something, cause you wouldnt do it. or, other people have failed at it, so they shouldnt do it either.

all that being said, let me also add, ofcourse I didnt just trust my port job. I did a rough version, took it into a pro, got there advise, revised somethings, and continued on. then had them tested to make sure I didnt make junk. I also recomend you find a pro near you, and do the same thing if you do decide to try this.