Polish and Port, take 1.

I used my old 0331 head to try my hand at polish and porting before I hit my 0630 that will be going on the engine. Basically I wanted to get a feel for the different bits and try it before I go mucking up the 0630. Lets take a look at the pics.

Intake:






Exhaust:




Combustion chamber close up:


A few comparing before and after:






I started at 5 and finished around 8. I went from a carbide burr, to the grinding stone, then to the 40 grit rolls, then to the 80 grit rolls, then finally to the cross buffs. I didn't really care that much about hitting the valve seats and I did a few times, but I will be careful on the real deal. I found that the carbide bits cut really fast... i made the mistake of attempting to unshroud the exhaust valve with one, that is why it is so lumpy looking. I didn't have my manifold gasket with me so I just went off of the marks form the original gasket. Not sure if I will open up the intake that much or not on the final one. Neither of the ports are actually polished, only the combustion chamber, which I know requires a bit more work. Also, there are a few bits in the runners that I would like to make a bit smoother. I will also be putting dowel in the valve guides to protect them and using old valves on the combustion chamber polishing. I did encounter a problem with the cross buffs... they won't fit in the exhaust port.. its just too big.. suggestion on that?

So, whats the verdict? Am I on the right track? Where do I need to put more effort in?

Oh yeah.. any one have a pair of valves that I could use to protect the valve seats?

-Chris

Seeming as I have never done a P&P, I can't give a fair judging, but from books I have studied, it looks good!! :cheers:

A few quick notes.
Remember that porting is all about the application, so some of the stuff you read online may be correct, but will not help and possibly hurt your port and HP/Torque curve.
When you are using the carbide make sure you don't shank it out in the port or loose conroll (too much chatter) around the valve guide because it will bend the steel mandril. I've bent and broken a few carbide burrs.
Don't waste your time going from The carbide to the stone stone - 40 - 80 - polisher. I just go from the carbide to the 80 grit and maybe a polisher (depending on application). On this job I would use the polisher, either a flapper wheel or a scotch brite wheel on the chamber and the exhaust port to slow the carbon build up in the chamber. I would stop at the 80 grit on the intake, maybe the 40 in the intake port. That is to keep a thin boundary layer to keep the fuel from sticking and collecting on the port walls. The one place I am consitering using the flapper wheel on the intake is on the short side radius (short turn) to reduce flow seperation at higher lift.
Don't worry about the low spot to either side of the valve guide. Other It is effectivly a dead area in the flow path. Just knock the casting flash off of it with the carbide or stone and hit it with the sand paper and round off the leadig edge of the guide.
Do some research on the short side radius shapes and their flow characteristics for a low rpm vs a high rpm engine.
Have you thought about going to the chevy valves or is it not in your budget?
I'm going to be porting a head soon, once I get my 8.8 built and under my DD. I might start the porting work in a few weeks.

~Alex

I though about chevy valves, but I haven't heard a lot that the valves are actually the weak spot in the 4.0L head flow. I am still considering them, but right now i may be over budget as I may purchase a brand new 0630 casting and hold the used one I currently have for another stroker build.

Also, i'm not going to hog out that much... just planning on smoothing some things out and polishing what needs to be polished. I did take a bit more off the guides than I wanted to.

Without a flowbench, "smoothing out" and "polishing" are all you can really do effectively. Increasing airflow isn't solely about port size - the shape of the port is a huge factor as well (you can remove material that would actually end up reducing airflow...)

If that's a throwaway head, what would I have to do to convince you to throw it my way? I've been trying to collect at least one of each for analysis - I have a 2685 (last of the 258's,) two 2686's (RENIX,) and a line on one 0331 (OBD-II/DIS,) another one wouldn't go amiss. That just knocks me down to one or two 0630's and one or two 7120's.

Considering I plan to section them with a bandsaw, I don't care if they're warped or cracked.

Given what I'm seeing, tho, it looks like you're doing a good job of polishing up the port. As I said, do not try to change the shape of the port without a flowbench for "before/after" comparisons, or you won't know if you're doing anything useful.

When you port-match to your gasket, "ramp in" at least three times the material you've removed at the port face. i.e. - If you remove 1/32" at the port face to hit the gasket line, carry that in and blend to at least 3/32" inside the port. Leave the slight "shelf" at the exhaust ports, it acts as an "anti-reversion baffle" to keep too much exhaust gas from ending up back in the cylinder. The EGR valve was deleted, its function replaced by a combination of camshaft timing changes and exhaust gas reversion - cleaning up the port won't really harm anything, but limit your efforts to a simple polish and cleaning up of the sand-cast surface and any "core flash".

5-90 that is pretty much my thinking. I don't want to reshape anything becasuer I don't have a flow bench to test it.

One thing I would like to clarify is the shelf you are talking about on the exhaust port. I think I know, but not 100%sure. Are you referring to where the ports appears to neck down t hen open up again?

What Jon's saying is that the exhaust ports should be smaller than the holes in the exhaust manifold(it won't be a problem cause those 0331 exhaust ports are small--I'm glad I didn't have to port that head). Anyhow Jon, It would be fun to cut them heads open. Are you gonna take notes/measurements for each port in each head? I know with them D-ports I was a little cautious about rounding out .

That is what I thought he was saying.

Still got a bit of a square edge on the valve guide bosses. I'd knock that corner down if not round it out completely.

The Port walls are approx .200 thick except for a thin spot at the short side radius. Its maybe .150 thick at the short turn. I didnt measure the wall thickness yet but I do plan on it, i might sonic check it. There is alot of casting flash in the ports on the heads that i have seen, so just cleaning that off would pick up 10 to 15 CFM @ 28" of water.
you don't need a flow bench to do any major porting if you have done alot of porting in the past. If you wanted to do any more than the basic fluff job you should ask the machine shop who is doing the surfacing and valve job for a few pointers. Most of the guys I work with don't like porting, so if they can just point the customer in the right direction they will gladly do so.
Also, a 3 angle valve job on the intake will improve the low lift flow and a radius valve job on the exhaust will help the overall flow.

~Alex

gradon said:

What Jon's saying is that the exhaust ports should be smaller than the holes in the exhaust manifold(it won't be a problem cause those 0331 exhaust ports are small--I'm glad I didn't have to port that head). Anyhow Jon, It would be fun to cut them heads open. Are you gonna take notes/measurements for each port in each head? I know with them D-ports I was a little cautious about rounding out .

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Yes, and yes. Notes and pictures.

The "shelf" has to be a blunt edge - that's why they don't do it inside the port (too much of a pain to make the core, then knock it out.) I've also seen headers where conic baffles were welded inside the tubes like little funnels - same idea, just a different method. I'm not sure which works better.

But my plans for these "research heads" will be to section one cylinder (roughly .200"/slice,) and then section the rest of the head "by cylinder" (probably through the screw holes) for porting experiments. Should save me having to wave around an fifty-pound iron casting (when I could just move around an eight-pound or so section.)

Looks good. Keep the intake rough, about 80 grit. Try and get the exhaust smoother for heat rejection. The bowl goes either way. I tried to get mine polished.
One the Chevy valves, you might look for Elgin valves on E-Bay. I think I went with Racer's Outlet in Indianola, IL. I remember he discounted four vavles for me. I used the Jeep springs, but machined standard Chevy spring retainers. I made a tapered mandrel with a screw to keep the retainer on. Then machined about .040 off the OD of one of the steps so the spring would seat on it. I think the valves were about $5.50 each, then the cost of the retainers and keepers. I remember the machining for the valves to the head being $175. I remember using the Chevy type stem seals, not the umbrella type.
Tom

75SV1 has a very good point. You really need to make sure that you don't polish the intake up to much. You may run in to a few idle issues if you do. Other than that it looks good!

75SV1 said:

Looks good. Keep the intake rough, about 80 grit. Try and get the exhaust smoother for heat rejection. The bowl goes either way. I tried to get mine polished.
One the Chevy valves, you might look for Elgin valves on E-Bay. I think I went with Racer's Outlet in Indianola, IL. I remember he discounted four vavles for me. I used the Jeep springs, but machined standard Chevy spring retainers. I made a tapered mandrel with a screw to keep the retainer on. Then machined about .040 off the OD of one of the steps so the spring would seat on it. I think the valves were about $5.50 each, then the cost of the retainers and keepers. I remember the machining for the valves to the head being $175. I remember using the Chevy type stem seals, not the umbrella type.
Tom

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Do you have a picture of the machined retainer?

~Alex

alex22 said:

Do you have a picture of the machined retainer?

~Alex

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I don't think I have a picture of them. I might have a spare laying around and the mandrell. I'd have to check. If you have acces to a lathe, it is not to difficult to machine them. The OD of the Jeep springs are roughly .040 or so smaller than the Chevy springs. There is some minor length variations in Chevy valves. I used Mopar Roller rockers, so they are adjustable. I went with 2.02 Chevy Intakes and 1.6 Exhaust. I would probably go with 1.95 Chevy and the 1.6 Chevy. The Jeep head from my understanding is a bit weak on the exhaust side. The guy who did my heads had no problems with the 2.02 valves, but said the 1.6 valves just fitted in.
If I can find the retainer I think I machined, I can send them to you. I think I should have two machined.
Tom

I know about not polishing the intake to keep up some turbulence, and I will polish the exhaust as best as possible if I can figure a way to fit the cross buff in it. Might see if there is one for a dremmel. As for the springs, I am going to stay with the stock ones. I heard from a few reputable sources that the valve isn't considerer a weak spot. I'm probably going with my set of Mopar Performance springs with a seat load of 100#.

A Dremel doesn't have the torque to get much done in there - that's why it's used for light jobs (a Dremel works more on speed than on torque. It turns 15-30Krpm...)

Check out what's available from Cratex abrasives and see what you can find that will work - I'm sure they have something, and they do lots of kits for mechanics and gunsmiths, so they cover a wide variety of applications.

You can also order from Cylinder head abrasives, MSC, joe mondello and Scummit (eew) just to name a few. If you have an air compressor that can handle it the air die grinders are very nice, torque and rpm's. One thing to watch out for is bent carbide burrs in high torque electric grinders. I was using an aluminum burr in a lower power makita grinder then switched to a 6.5 amp craftsman because i had to remove alot of material. The shank was bent slightly so the lower power grinder would just shake a little at lower rpm. When I switched to the biger one it was nice at high speeds but once i let off the foot pedal and as it slowed to the shakey rpm the shank bent about 70* away from straight. Kinda scarry when a 8 inch long carbide burr does stuff like that. Just a heads up, and hold onto the grinder tight and stay in controll all the time.

~Alex