Momar

Well, the title says it. I am going to start porting my sportsman II heads soon and would like to know if anyone has done a set of these before and has any specific tips? General tips welcome also as this will be my first time porting anything. I have done a lot of reading and have seen somoene work on doing some porting, but the fewer suprises the better. I dont want to screw up these heads.

Ben

Vader

I guess not. Let us know how it works out. My only advice would be to take measurements, and check periodically to make sure you aren't pushing the limits of the casting thickness. Once you have one done to your satisfaction, you can simply match the rest.

Momar

Well, actually the reason I am doing this is because I bought them used. Either the guy I bought them from or the shop he got them from lied because I was told that they were ported when i got them. They were supposed to flow about 265 cfm intake and 180 exhaust.

Well, when I got them I pulled a few of the valves out because I could see that one of the intake ports looked "fresher" than the others. It turns out that only one intake port was ported. Oh, I was mad. I was hoping to put them on this weekend. Anyway, it appears that they ports were all gasket matched(I think to a felpro 1205). The one that IS ported appears to be done pretty well. The valve guide is trimmed down and all of the casting roughness and ridges are removed and maybe a little material, but I havent really measured yet. I think that I may try your card template idea to see how the shape of the one that is ported compares to how they were in stock form.

I was reminded by someone that David Vizard's "Max Performance Chevy Small Blocks On a Budget" has tips on porting the sportsman II's which happens to be a book I have luckily. Anyway, it will be a couple weeks before I will be able to start porting them. I have a die grinder, but need to get the carbide tips, stones, sanding rolls and ect... that I will need.

I figure that I will check out the one that has already been ported and see if there is anything I want to modify on it. If there is I will do so and then try to copy that one to the rest of them. Hopefully that cylinder actually flows the 265 cfm and 179 exhaust like the guy I bought them told me the heads flowed. he said that the shop ported the heads and built his whole motor. He said that they had it 500 miles ago and ported the heads then and that they were stock until then. I really honestly dont know if the guy is the one lying to me or if it was the shop that lied to him.

Thanks

Ben

Momar

Here is a flow sheet that he claimed to have been when the heads were completely stock.

Ben

Vader

Momar,

Wow. Sorry you got reamed. Now it looks like you get to do the rest of the machining.

As for the port finish, personally, I wouldn't wast the time polishing the intake runners (and never do) a bit of surface imperfection is not only NOT a hindrance but can actually be beneficial on the intake side in a street application. Obviously, any of the big humps, casting imperfections and mold marks, parting lines, and things like that should be cleaned up, but marks left drom the stones and burrs aren't a problem at all.

Of course, the exhaust sides should have a fairly smooth, lightly polished surface to prevent heat gain and carbon accumulations. The same can be done to the chambers, but perheps a little less polish is necessary to accomplish the desired result.

rhuarc31

Vader's right, don't polish the intake ports, what very minor added flow you'll see will be offset by the loss of fuel atomization. Admittedly less of an issue on FI'd cars, but still important. Items' I'd concentrate on in general (not specific to sportsman II's).
1. Use a head gasket and mark your cylinder bore. Then make sure the valves are unshrouded as much as possible. Check the shallow side of the chamber as well. A lot of aftermarket heads shroud the valves a bit there.
2. Smooth the entry into the entry into the chamber, BE VERY CAREFUL or you'll be paying for a new valve job, I like to drop an old valve in to protect the seats when doing any work in the chamber. But you have to pull it out to get the slight ridge left by the average valve job.
3.Smooth out any ridges in the throat, lot's of heads have ridges there where the seat meets the head.
4.Make sure the short side radius is a nice smooth curve
5. When working on the exhaust port DO NOT lower the floor at all, that's already a poor area, dropping it will cause flow reversion and hurt overall flow.
6. If the exhaust ports are D-shaped, DO NOT hog them out to a rectangle, that also causes flow reversion, hurts exhaust gas velocity and scavenging.
7. Remember that the shape of what's left is the important thing, not how much material you remove. Smooth rounded curves with no major bumps or ridges.

If you can get hold of the manual for a superflow flow machine it gives an excellent explanation of basic airflow theory in laymans terms. Easy to understand and a really good guide to basic porting.

Momar

Thanks for the tips. I have read most of that before but it is all apprecaited because I would rather hear something more than once than miss something important. As far as the intake ports, I dont plan on polishing them. When I said I was going to smooth them, there are some pretty big ridges and stuff in the port that I would like to get rid of. The one thing I didnt realize until recently(when I realized I was going to have to port these and started doing some readin) was how you want the short side radius shaped. Looking at the heads and pictures, I can actually picture kind of how you want the air to flow. I can see how if you trimmed down the short side radius so its not as much of a radius especially on the exhaust how it would cause it to run right into the port wall. On the intake side, it looks like a lot of what it would do is just keep the velocity up going into the cylinder.

Again, thanks for the help. I will continue to read up on this until I am able to get the rest of the supplies I need to do this. Oh, by the way, does anyone know of anything that takes carbon off of valves well?

Ben

Momar

So, if I were going to swap my cam when I do this what would be a good match to the heads. I guess since I dont have actual flow numbers yet that I am kind of hoping to get around 265 intake, and am not sure about the exhaust. I was told that the heads flowed 265 and 179 after ported, and these would seem to be possible numbers with these heads. I know that only one cylinder was flowed and I dont know if these numbers were made up or if these were actual numbers for the "one" cylinder. If they were for the one cylinder they didnt even touch the valve guide in the exhaust cylinder.

So does anyone know what it should cost me to have a couple of cylinders flowed? I want to see how well the ported one flows and how one with just the gasket matching flows. I basically want to do this to see if the numbers he gave me were real at all or completely made up.

Ok, back to my question about the cam. Asuming I can get around 265 intake and somewhere a bit over 180 exhuast out of these what cam would be a good match? I currenly have the comp cams xe268 w/ 224 230 @050 and .477 .480 lift w/ 1.5 rockers. I have been considerin going a bit larger but still want to drive it on the street. I kind of like the xtreem energy series, but would be open to other sugestions. This is the first motor I have had that has really had any heavy mods, so I really dont know how much duration makes how much effect in the idle. Right now I can idle around 600 in drive, but could live with it up around 800 or maybe 900 if needed. Do you think I should just stick with what I have or would something else do better? Oh, and how much difference would a true roller timing chain make(I have stock replacement right now)?

The rest of my setup is hooker long tubes with dual 2.5" exhaust with h pipe and dynomax bullets, performer rpm intake w/ computer controlled quarajet(secondaries have dr rod and b hanger and have been modified to open all the way). I have a reubild 700r4 w/ 3000 stall and shiftkit, alum driveshaft, and 3.45 posi rear. I have accell dist cap, rotor, coil, wires, plugs, and plan to get an ignition box eventually(probably msd 6al).

Thanks for all the help.

Ben

Momar

Well, I just talked to the guy I got the heads from. He said that he took a couple of his friends that knew about cars with him and went to the shop that did the heads/were currently building his motor/car. He said that his friends pointed out several things that the shop had taken corners on while on his current motor that they were building. He said that he took his car home in pieces instead of letting them finnish. Anyway, he said he would refund me $100 bucks which should cover the cost of the stuff I need for the porting. I will still have to put some time into them that I hadnt planned, but I was wanting to learn to port my own heads anyway.

Oh, also, I ordered David Vizards book on porting small block chevy heads. He had a small section in the his budget small block book on the sportsman II heads, but mentioned that he got into more detail on them in this other book. I figure I will do some reading before I start because I want to do this right.

Thanks

Ben

rhuarc31

The comp cams XE series are good cams, and the 268 is perfect for the street. If you wanna go just a bit larger, get some 1.6 roller rockers. As far as flow testing 100-150 bucks to get all 8 flowed. If you just want a couple flowed 50 bucks maybe. If a shop around you has a flowbench. Damn things are around 10 grand to buy, though you could build one for substantially less.