I am doing a bit of porting and clean up on my "781" open chambered heads. I have a "how to" bulletin from Standard Abrasives on the proper way to go about doing this. They mention a spray that you apply to the face of the intake ports so that you can scribe a line on that face using your intake gasket as a template so that you can see how much metal to remove. Where can I buy this spray paint and what is it called specifically?
Also, should I use a grinding stone or a carbide burr to do the porting at the intake ?

Thanks y'all graemlins/thumbsup.gif

Just use a permanant marker to color the area then put on the gaskets, and scribe the port openings to the gasket.There are different burrs one for cast iron might not work for aluminum intake,and alum.will melt into pores on a stone! graemlins/waving.gif

Someone mentioned in another post that you should not match the ports to the gasket since it could cause a bulge in the matched area and could disrupt flow.

Not trying to tell you what to do but it does make sense. I guess to match the ports you would have to make a template.

Dykem & it comes in red or blue spray cans like paint.
Any industrial supply house.
Carbide burrs but I woud suggest practicing on an old piece of aluminium until you realize what the term "death grip" means when holding your grinder.
Use almost NO PRESSURE on the burr, let it do the cutting.
Spray the burr with WD40 or use an old candle (wax) & the aluminium will not stick as bad.
You will want to finish with cartridge rolls. (I normally use 80 grit for finish) Leave the intake a little rough, don't polish it.
Do not open it to the gasket unless the gasket happens to fit the head. (highly unlikley)
You want to make the intake outlet just slightly smaller (.010 or so) than the head.
Put some paper on the head (I use the kind that sticks when you pull off the backing like a decal) & make your own template then stick it to your intake & PUT ON SAFETY GLASSES & have at it :D

Originally posted by Wolfplace:
Leave the intake a little rough, don't polish it.
Do not open it to the gasket unless the gasket happens to fit the head. (highly unlikley)
You want to make the intake outlet just slightly smaller (.010 or so) than the head.
Put some paper on the head (I use the kind that sticks when you pull off the backing like a decal) & make your own template then stick it to your intake & PUT ON SAFETY GLASSES & have at it :D Mike, I want to be sure I understand and do this correctly.
My intake ports on the heads are slightly smaller than the Felpro gasket currently by approx. .06" to .12" guesstimate. Should I match this intake port opening on the head to the gasket using the scribed line and paint/marker? And should I round this edge at all ?
I understand why I want to leave .01 on the "intake manifold" port (smaller than the head).

Thanks again graemlins/thumbsup.gif

Originally posted by Texas70:
</font><blockquote>quote:</font><hr />Originally posted by Wolfplace:
Leave the intake a little rough, don't polish it.
Do not open it to the gasket unless the gasket happens to fit the head. (highly unlikley)
You want to make the intake outlet just slightly smaller (.010 or so) than the head.
Put some paper on the head (I use the kind that sticks when you pull off the backing like a decal) & make your own template then stick it to your intake & PUT ON SAFETY GLASSES & have at it :D Mike, I want to be sure I understand and do this correctly.
My intake ports on the heads are slightly smaller than the Felpro gasket currently by approx. .06" to .12" guesstimate. Should I match this intake port opening on the head to the gasket using the scribed line and paint/marker? And should I round this edge at all ?
I understand why I want to leave .01 on the "intake manifold" port (smaller than the head).

Thanks again graemlins/thumbsup.gif </font>[/QUOTE]On the head I would open the head to the gasket on a rat as long as we are talking a small amount. This way you are making them all the same. Blend them down into the port at least an inch or so, I like to go as far as I can.
You don't want to make a "funnel" out of the first part of the opening into the port.
The idea is you want to keep the port cross section fairly constant, not to just make it bigger in spots.
The inlet & first part of the port is the best flowing part so making it bigger is useless until you can get enough air around the valve & short turn/ bowl area. This is where you make big gains.
You don't want to round the edge, leave it square. You can use the gasket for your template for the intake & just stay inside the lines. Match the intake port to this opening & blend up into the intake as far as you can trying to make a smooth transition just like the head.
You don't need any WD40 or anything for cast iron, do it dry.

Wow, thanks Mike, I'm ready to go now that I understand clearly. Thank you for your advice. graemlins/waving.gif

What about setting the heads and intake on the block being used, fitting a gasket to the larger of the two ports and useing persian blue transfer dye ? Just gasket matching the intake and heads does NOT insure that they are matched up when installed.

Originally posted by Wolfplace:
Dykem & it comes in red or blue spray cans like paint.
Any industrial supply house.
Carbide burrs but I woud suggest practicing on an old piece of aluminium until you realize what the term "death grip" means when holding your grinder.
Use almost NO PRESSURE on the burr, let it do the cutting.
Spray the burr with WD40 or use an old candle (wax) & the aluminium will not stick as bad.
You will want to finish with cartridge rolls. (I normally use 80 grit for finish) Leave the intake a little rough, don't polish it.
Do not open it to the gasket unless the gasket happens to fit the head. (highly unlikley)
You want to make the intake outlet just slightly smaller (.010 or so) than the head.
Put some paper on the head (I use the kind that sticks when you pull off the backing like a decal) & make your own template then stick it to your intake & PUT ON SAFETY GLASSES & have at it :D EXACTLY what I was thinking.

Also, when using a carbide bit on aluminum keep your grinder speed slow or you will clog up the bit. It will actually cut faster at a slow speed. If you do clog it up, just grind on an old piece of cast iron and it will usually clean out.

Please don't forget to use ear protection and wear a dust mask. No, I'm not kidding. Gloves as well, or you will be picking metal out of your skin for a day or two. And don't get hung up on gasket matching the ports. Virtually all the potatoes are in the area below the valve, the 'throat' and the 'bowl'. Reducing the valve guide bosses can also be a waste of time. Also, don't bother lowering the floor of a port to much. But you know what? We were grinding on my brother-in-law's sb chev heads a couple of weeks ago, and found a huge casting bung in exhaust port #7. This was a serious restriction. It ain't there anymore. So do get those, if present. And, whichever way the drill wants to pull the bit, pull it in 90 degree sweeps in the opposite direction. Do all of the cuts on the side of the head you are working on, and then flip the head over, so you are always sort of pressing down, not up or to the right or left. A good grinding bench is 2x4's cut about 16" long, and then nailed together in alternating layers like a funeral pyre. {no, really!} This is about 14" high and goes on top of your grinding desk or workbench, and gives you a comfortable stance, depending on how tall you are. Have an office lamp that can be moved around on it's articulating arms {you know the one}, so you can provide yourself with light. If you have a fan on a stand, have it running so the chips blow away from you. I gotta set this up in my shop in a week, {we're doing v6 buick heads}, and then I'll post a picture. Just little things I have seen.

Some great advice ejrempel.... I will be cleaning up all ports, taking off a bit to give myself a set of "ported" heads (because if I can get just a little more flow, I'll take it. This could make the difference in a heads up race) and making sure to get rid of all casting "bungs". I will then use the 80 grit to polish the intake ports on the heads. I will verify that my intake manifold ports are appropriate in relation to the ports on the heads as Mike (Wolfplace) stated earlier. Thanks again for all the help and I am ready for some porting and polishing. graemlins/waving.gif

Here is one vote for USING WD40! My experience has been that using liberal amounts of WD while porting leaves a much smoother surface. Not too smooth, but smooth enough that you don't have to do any additional work on the intake side as you don't want a polished surface on the intake side. When using it on the exhaust side, it will drastically cut down on the time needed to polish the surfaces with a sanding roll once you are done with the stones. Try grinding on an old head first with a dry stone, and then with a stone sprayed with WD, and then run your finger across both spots and you will see exactly what I mean.

When I am porting, I spray the head and the port repeatedly. This serves to keep the dust down, drastically reduces heat in the head, and extends the life of the stone.

Have fun with your project!

FWIW
I like to stick the hose from my shop vac into the opposite end of the port I'm working on. (i.e. If i'm working on an intake bowl, I put the hose in the intake opening of the head.) This keeps the flying chips and dust to a minimum.
I like to wear a clear plastic face shield as your field of view is better and it has better ventilation.
BE S

Yeah, the shop vac idea is pretty good, and everyone has them. Since you're wearing ear protection anyway, no problem. The faceplate would reduce sweating.

These are all great tips and I really appreciate all of the info you guys have provided. I will have a great set of heads when I'm done.

Let me make sure about something... am I only supposed to "polish" the exhaust ports of the heads ? What about the intake ports and the ports on my Performer RPM intake ? I understand what needs to be ported (ground), but I'm not positive about the "polishing". ;)

Great post, I have learned a lot here...

Originally posted by Texas70:
These are all great tips and I really appreciate all of the info you guys have provided. I will have a great set of heads when I'm done.

Let me make sure about something... am I only supposed to "polish" the exhaust ports of the heads ? What about the intake ports and the ports on my Performer RPM intake ? I understand what needs to be ported (ground), but I'm not positive about the "polishing". ;) For a carbureted engine you want to polish the exhaust & the chamber but do not polish any part of the intake port. An 80 grit or so finish is fine for the intake.

Just put in an order for carbides today. Here is a good place with nice people. www.ruffstuff.com (http://www.ruffstuff.com)
That company is Cylinder Head Abrasives

This is out of my league, but i'm just curious. Why wouldn't you want to polish up the intake ports also? I have a set of Performer RPM's too and i think whoever had them before me might have polished up the intake ports. Just have to check. thanks

Originally posted by pegleg71:
This is out of my league, but i'm just curious. Why wouldn't you want to polish up the intake ports also?
I believe it is to help promote the air and fuel to tumble,thereby further mixing the combo and allowing better combustion.The further that a mixture of liquid and air go the more the liquid tends to drop out of the mixture.

In other words, it allows a more complete burn of the available mixture.

Having a rougher intake port surface helps keep the fuel air mixture in 'suspension'or in other words keeps the fuel from dropping out of the mixture.

Thanks guys....AGAIN. This really did turn out to be a very productive post. I will be sure to only polish the exhaust ports and chamber area. :cool:

Pegleg71, my heads are GM "781" cast iron BTW. I have a Performer RPM intake manifold that I may be doing a slight port job (gasket match) to, of course making sure to keep it slightly smaller than the ports on the intake ports on the heads. ;)

Thanks for the link ejrempel graemlins/thumbsup.gif

That Standard Abrasives article is pretty much a waste of time...it is not real detailed and there pictures will def. send you on the wrong track(if you look at the cross section of the intake ports they funnelled the beginning of the port into the rest of the port and didn't straigthen the roof out which is where the air is flowing.

I would reccomend David Vizards book on how to build and modify chevy small block cylinder heads(I know you have bb heads but I don't imagine there is much of anything different and the same principles still apply).

I've started work on my world s/r heads....it takes a lot of time, let me tell you! I'm gonna have 40 hrs in them before I am done but I work at a slow pace. Heres some pics of the intakes 80% done. http://community.webshots.com/album/110849581wiVloK

PS- A note to anyone...do not buy world s/r heads...the quality of the castings is worse then stock in MHO(the practice 624 heads I had look better)...there is huge descrepencies in the conformity of the different ports(some had the valve throats already opened up to 83% while othere were like 75%.

Correct!! You do need to polish the exhaust ports. This cuts down greatly on carbon buildup. Your Standard Abrasives kit should have come with a flap wheel for polishing the exhaust port. As far as the the intake goes, just remove some material in order to kind of port match it. I used a carbide round head tool and it worked well on the aluminum intake as well. But turn down the air regulator on the air compressor. I ran mine at about 50psi. After all the major material is removed then you smooth it out a little with the conical sanding wheels also included in a Standard Abrasives kit. I have also heard good and bad things about Chamber polishing. I polished mine slightly, but not extensively. Good Luck!!