Porting Heads - What to document?
 

I tried to post this in What Have You Done to Your Truck Today, but it won't let me insert pictures. However, it seems to let me here so I'll just start a new thread.

Got started looking at the heads I'm going to port and, having a spare head and a powered bandsaw, here's what a cross-section at the exhaust port of a D8OE looks like: (More pictures in my Explorer album here Ford Truck Enthusiasts Forums - Gary Lewis's Album: '82 F150 Explorer)

https://www.ford-trucks.com/forums/p...ictureid=79327

I've pointed out where the air injection port is, and have drawn a line showing roughly where I think I need to cut back to. However, straight lines aren't that good in gas flow so the actual line should probably be a curve that approximates the bottom of the port, with the intent being to keep the volume the same.

The hole for air injection is roughly 1/4" in diameter and I'm thinking about drilling them to a standard and driving a piece of rod in to block the hole. However, there's the question of whether the rod will fall out, so another approach would be to tap the hole and run a bolt in and anchor it with high-temp Locktite. Thoughts?

Which brings me to you - I'd like your input as to what and how to document this process. I'm thinking about a set of before, during, and after pictures as well as a description of the tools I use. Further, any learnings about what didn't work will be included.

What am I missing? Your input would be appreciated.

Thanks for the picture, I didn't know how the AIR system worked.

Just looking at it, I don't think it really makes a difference whether or not you plug them. If you do, I think it would be much better to tap the hole and use a bolt to plug it.

AIR stood for Air-Injection Reaction or Reduction, IIRC. The AIR/smog pump put air into the back of the heads via a manifold, and it traveled down a passage you see as the round hole at the top of the air injection port, and thence into the exhaust port. The extra oxygen caused some of the unburned hydrocarbons to ignite in the hot exhaust gases, and helped the cat burn the rest of them when they got to it.

Oddly enough, only 3 of the 4 exhaust ports have the air injection port drilled on these heads. I don't know why - does anyone?

WOW! Look at that restriction!!! No wonder people remove those "bumps". Looks to be about 30% restriction, you think? Thanks Gary, for showing us that...makes much more sense now.

I've heard of removing those, but I don't think I've heard of having to plug the hole that's left. What do you know about that?

I'd say 30% is a reasonable guess. As for plugging them, people say it isn't needed, but if it is easy to do then why not? It would make the flow smoother (laminar) which is what you want. Nice and easy with no bumps or stubbing of toes.

What is your overall plan for these heads? Ford heads have more problems than just the bump, but I am not against grinding the bump out on a otherwise stock installation.

So what is your porting plan? Are you going for smaller passages for torque, or are you building a higher rpm breather?

Torque. The cam comes in from idle. The torque converter is a low-slip one. All things good for a truck that needs torque. Even using the factory intake and exhaust manifolds, but true non-cat duals from there back.

Here's a status update. Spent the day grinding on the cut-up head and taking pictures thereof. In the process I learned several things:

• There's no need to tap the air injection ports and plug them with a bolt since you wind up grinding almost all of the bolt out and still have a small hole at the top.
• It doesn't really take long to grind out the exhaust bumps or blend the intake's bowl
• It is easy to take too much material off the edge of the valve guide.
• The exhaust ports in the heads are too small to match the exhaust manifolds so take some cleaning up
• Taking decent pictures is more difficult than grinding!

There are several pictures in my albums here: Ford Truck Enthusiasts Forums - Gary Lewis's Album: Porting D8OE Heads And, some of those are shown below. However, I'd really like to hear from ya'll as to what you are looking for in a how-to.

Here's a view of the bump in the exhaust as seen through the valve:
https://www.ford-trucks.com/forums/p...ictureid=79389

Here's a view of the bump through the exhaust port:
https://www.ford-trucks.com/forums/p...ictureid=79390

And here's the bump ground out, as seen from the valve side:
https://www.ford-trucks.com/forums/p...ictureid=79392

Here's a view of the exhaust port with the gasket edges scribed:
https://www.ford-trucks.com/forums/p...ictureid=79394

And here's the port opened up to the scribe marks, albeit not perfectly"
https://www.ford-trucks.com/forums/p...ictureid=79395

Now for the intake. While it is far better in stock form than the exhaust, while here I might as well clean it up. Here's a view of the bowl before blending, showing both the blunt guide as well as a lip where the machining for the bowl ends:
https://www.ford-trucks.com/forums/p...ictureid=79397

Finally, here's the blended bowl showing both the guide and lip blended:
https://www.ford-trucks.com/forums/p...ictureid=79410

Lookin good Gary. Are you planning to blend the area right under the valve seats? I've just finished porting some E7's and they had alot of extra iron in that area.

Are you using stock exhaust manifolds? If I recall correctly from my research last year, gasket matching is not really recommended, but port matching is.

Well, I'm not sure if I'm port matching or gasket matching. As it turns out, the Felpro gaskets are a perfect match for the exhaust manifolds I'm using - which answers that question yes. So, I'm matching the ports to the gasket which matches them to the exhaust manifold. Is that bad?

As for the bowls or area under the valve seats, I am cleaning it up. Nothing major as the heads are already machined and I sure don't want to hit a seat or guide. But, I will smooth things so there are no lips, steps, etc.

Any suggestions would be appreciated.

I take it you`re using cast iron manifolds then and you shouldn`t have a problem. The reason I mentioned was I almost made the mistake of gasket matching my heads before I had my headers. Had I ground them out the ports wouldn`t match up very well.

Yeah, careful of those seats. I nicked mine in a couple spots, but they should be ok after lapping the valves.

Without blocking the AIR ports, would there be flow through that passage from port to port? Just thinking out loud.....

I would spend some time on the short side radius too.

Yes, there may be some flow port-to-port. But, it is only a 1/4" hole. And, the problem I had was that my taps aren't long enough to put threads all the way to the bottom (top, actually) of the hole and I can't get a bolt all the way in because of that. So, when I grind the bump out there's still the little bit of hole left at the end of the bolt.

And, that means the bolt is sorta-kinda laying in the threads of what's left of the hole, with only the back side of the bolt in there. With the heating and cooling that will occur I'm afraid it'll drop out at some point. Overall, I think I'll pass.

Yes, I'll work on the short side. But, I don't want to flatten it since the flow needs to be curving up against the top of the port so it'll continue curving as it goes into the manifolds and head down. Don't want to interrupt the flow.

I only mentioned the short side as it looked like you had not gone there yet.

I was thinking the "flow" through the AIR port would not be much, but just wondering if it would make a difference. Probably not, just my usual overthinking the problem self.

You can open up the port to match the back side of the valve seat cutouts. I would on the short side, and more blend it on the other side.

Also looks like you are shaping the valve guide areas. Taking away more of the guide will open area for flow, but increase rockling of the valve in the guide. Really not necessary for a torque motor.

I'm looking at the cut-away and see what you mean. The short side protrudes into the path the gas would like to take, so needs to be cut down a bit. But, on the other side there is plenty of room and little, if any, cutting needs to take place.

As for the guide, I'm not not planning to take any of the guide itself away, but smooth the edge a bit. What I did on the cut-away was too much. In fact, I only showed the one with the least metal taken away as the others were over the top. Anyway, thanks, I'll take it easy.

And I, too, over-think things. That's how I got to tapping and filling the AIR port when everyone I found on the web said don't bother. And, once I did it I realized there's really no easy way to fill it in a way that for sure won't fall out - which could be bad news depending on where the filling went. So, I think I'll pass.

But, if flow between the cylinders is a concern then a rod could be driven into the drilled passage that runs the length of the head. The passage measures .500" so you might get a 1/2" rod to seal if fairly well, but it wouldn't be perfect. Perhaps using high-temp Loctite?

Well, I finished the porting and polishing today. But, I should clarify that everything I read, and especially David Vizard's book How To Build and Tune for Performance with Economy, says that you should not polish the intake side of the heads as you need roughness to help economy on a carb'ed engine. So, while I've cleaned up the intake side slightly, I've focused 95% of my efforts on the exhaust side. While I've put lots of pic's in my album on porting the heads (Ford Truck Enthusiasts Forums - Gary Lewis's Album: Porting D8OE Heads), here's before:
https://www.ford-trucks.com/forums/p...ictureid=79389

And, here's the result:
https://www.ford-trucks.com/forums/p...ictureid=79726

I also lapped the valves to their seats, and here's one of the reasons:
https://www.ford-trucks.com/forums/p...ictureid=79715

And here's what the seat looks like after having been lapped with the valve:
https://www.ford-trucks.com/forums/p...ictureid=79723

And, here's what the valve looks like after lapping, with the shiny part being the surface the machinist ground, and the dull part being lapped:
https://www.ford-trucks.com/forums/p...ictureid=79724

So, my question to you is how should I document what I've done? Do I put on my web site and we put a link to it somewhere? I think that's the best way since I have quite a few pictures and a lot I want to explain.

Anyway, your thoughts?

Intake ports should be rough, as in coarse sanded.

Exhaust ports should be as smooth as possible to help flow and reduce the amount of heat transferred to the head.

Did you use sanding rolls or just burrs?

Valve seats after lapping look normal for a standard rebuild. For performance, I would have cut the seat down to about half of what you have there.

Swirl polishing the valves helps too.

Burrs on both the exhaust awa the intake. Then, on the exhaust I used a rough and then a smooth stone in the die grinder, followed by sanding drums in the Dremel.

And, I worked the short side of the exhaust as best I could, but that's difficult since you are pretty close to the seat when doing that. Thanks for that tip.

Edit: Forgot to comment on the seats. Yes, I understand they could be narrowed. And, a back-cut could be taken on the valve. But, I'm gonna stop here for reliability.

Exactly. For a daily driver, there is no need to go that far. The narrower seat does not last as long either. But if you have to take your heads to have the seats recut, then widening them is only a few more $$$. And then larger valves.....

I don't bother with stones. I go straight from the burr to rolls.

Glad to see you stopped from lapping too much. Seen too many that have a groove in the valve face from lapping. Too much lapping also makes the seat rounded and will not last.

How much stem clearance do you have?

Haven't measured the stem od nor the guide id, although I can do that. What should I have?

And, btw, the engine I "melted" had heads that had been reworked about 2k miles before. I'm not using them since they are D7's with rail rockers and also may be cracked from the heat, so I went w/the D8's. Anyway, the machinist for the D8's but on Felpro's black umbrella valve stem seals while the D7's have a seal w/a band that holds it to the guide. It looks like a better seal, so should I reuse them or is the umbrella fine?

Gary, would you mind adding that cross-section view of the exhaust port to your album? (Ford Truck Enthusiasts Forums - Gary Lewis's Album: Porting D8OE Heads)

Thanks!!

Umbrellas are ok for stock, but I always use banded. I never reuse seals. Would you reuse a rear main seal? Front cranksnout seal? They are not that expensive.

Put a valve in the head, without spring/retainer/etc and rock it in the guide. Grab the tip and see how much the valve moves laterally in the guide. If there is more than just a hint of play, it is probably too much. The exhaust side will usually have more play. I have found this true regardless of make or model. Honda A18/A20 heads are really bad about exhaust guide wear.

Too much side play will allow the valve to seat on an angle and not directly on the seat. This wears the seat and valve face. Also wears out the stem seal quicker.

Anafiel - I've added the cross-section and made it the album cover. However, it isn't the one that I'd put the red lines awa the arrow pointing out the AIR port. I could put that one out there, but I'm thinking about doing another one that shows the curve that I tried to put in there on the roof to get the exhaust gases to starting bending before they hit the exhaust manifold and have to bend quickly. Would that help?

Stang - Good point on the seals. And, I'll check the valves for rock, but I'm very sure there is none given how they fit today when I was lapping.

Anything, and everything. Helps to visualize the project. Sometimes I can look a dozen pics of something, and just not get it until the very last pic. That last angle could be the kicker.

The cross-section you had was one of those kind of pics, and if you have more like you said above, the more the merrier.

Thanks for the time you've taken with documenting this project. It's helped me, and I'm sure it'll help others. Good job, dude!

Speaking of cross section..

Any chance you could cut it the other way through a pair of ports?

I've added this, which is intended to show what I intended to grind out:
https://www.ford-trucks.com/forums/p...ictureid=79743

But, I apologize for the wiggly line. Anyway, if you could see another cross-section just a bit further in and right at the back side of the AIR bump you'd realize that the bump sits in the middle as an island. My intent was to take the island out and leave what would have been the roof w/o the island. So, I ground the bump until I got to the back side of its vertical passage and went just a bit further, sorta like the red lines show.

Stang, I'm not understanding where you'd want it cut. Try me again?

Am I the only one to rate this thread 5 stars???

When done perhaps Chris can sticky this to the top of the page.

As far as exhaust movement between thermactor ports, a few of the porters over on 460Ford and the old Network54 suggest just pumping them full of silicone caulk.
Sure it will char on the surface, but if any comes out it's only going out the tailpipe anyhow.

Jim - Thanks for the kind words. But, it's the help from the rest of you, and particularly Stang, that has made the difference.

As for making it a sticky, maybe Chris could change the title to Porting D8OE Heads when the time comes to ditch the "documentation" part. And, we could put a link to the writeup I'll do on my website in the first post so people can find it. I do think it would be helpful to explain my intent for the porting, which was more efficiency than power, as that changes where you spend your time, and I'll do that in a page on my website.

Re the AIR ports, I suppose it wouldn't hurt to pump them full of high-temp RTV. Most comments I've read say not to bother, but you never know about the source of comments you read on the Internet. The RTV approach is about the only thing I can think of that is safe, since the cast iron of the heads is going to expand away from anything you screw or drive in there, ultimately allowing it to fall out. And, since it is above the exhaust valve there is the possibility it'll come into the cylinder. I'll think about that. Thanks again.

As I said Gary, this was in regard to porting D3VE 460 heads. But the idea is the same.
Certainly the vast majority of the heads don't get hot enough to disturb the silicone, just the area right around the exhaust ports.
Doubt it could "fall into" the cylinder. Whenever the exhaust valve opens there is a lot of pressure on it's way out.

Carry on.
This is a GREAT thread! :-X22

Jim - I did a poor job of explaining my thinking. What I meant to say is that RTV would be safe as even if it did come loose I doubt it would cause a problem. First, as you point out, it is relatively light in comparison to size and would probably go on out the port. Second, even if it did go into the cylinder it would just get chewed up and then go out the port.

On the other hand, my fear of anything more substantial is the probability of it coming loose due to expansion and contraction, and it might well be dense enough to fall down, depending on when in the cycle it come out, and go into a cylinder. That could be catastrophic.

Anyway, I'm agreeing with you but just did a poor job of explaining it.

Those with EFI engines ought to consider if it is safe for their O2 sensors.
I know that there are "sensor safe" formulations as well...

The AIR bump should go, as you did. The short side radius should not get that much cut, at least at the red line. Cut back to there it creates a sharp turn at the valve seat area reducing flow. Instead, the short side radius should be smoothed and made an even curve from the runner to the vavle seat area.

I hope you don't mind I edited your pic...

http://i414.photobucket.com/albums/p...s/Untitled.jpg
Dang Paint made it bigger. Anyway, airflow around the valve seat at low lift is most important for overall performance. As such, the bump around the port just below the valve seat should be smoothed and the short side radius as above. Swirl polishing the backside of the valves helps here too. The rest of the porting helps more in the midrange/top end.

Stang - I appreciate you editing the pic. I probably didn't cut the short-side nearly as much as my line suggested, more like your line I'm sure. I just couldn't get a line where I wanted it on the picture, so thanks for doing that.

I'll probably re-draw mine for the final documentation to make a smoother line on the roof, move the floor line to yours, and add your arrows pointing to the bumps around the seats - which I did try to do but didn't do a very good job on. May go back there today due to your suggestion - thanks.

I do have a lathe and have considered back-cutting the valves - what are your thoughts there? And, how do I swirl-polish the back of the valves?

Edited another of your pics.

http://i414.photobucket.com/albums/p.../Untitled2.png

Leave an even space on each side of the seat. More important on exhaust valves for the heat dissipation.

The swirl is usually put on before the seat area is cut on the valve. I have done it with 3M Roloc discs and a drill with the valve chucked up in a lathe, but not very safe nor reliable(even). That is where the special attachment comes in that holds the abrasive disc at the correct angle against the backside of the valve. The whole idea really is to remove the roughness on the backside of the valve head as shown in the above pic. Smoother is better here.

Did you do anything about unshrouding the valves in the chamber?

Here is a swirl polished valve:
http://www.n56ml.com/corvair/phoenix/070223043.jpg

Ok, I'll take the sharp edge off of the valve in the lathe.

As for swirling, I'm not sure I want to attempt it free-hand. If I had a toolpost grinder then maybe. But, I have spare valves so will try something.

Didn't do anything about unshrouding the valves. Don't really know what to do there. Suggestions awa importance?

Forgot to say I'll cut the head the way you suggested and post pics.

I hope this isn't a stupid question, but here goes:

How does this affect engines that have/need to have their emissions systems intact? What I mean is, will grinding away the Thermactor hump render the system ineffective in any way? Or is this assuming that the emissions have been, or must be removed?

See what I'm getting at?

I fully see what you are getting at. And, the answer is "I don't know". Maybe some out there do, and I hope they'll chime in. Stang?

Having said that, I have read that the bump was to provide a flat spot that was at right angles to the exhaust valve so it could be drilled at the factory w/o the bit walking off. And, while I understand that having a surface perpendicular to the machine would make it easier, it can be done other wise. Further, there was obviously no need to have that big of a bump in order to have done that. In fact, some of the later heads had a smaller bump.

One thought I had was a venturi effect where the forward lip of the bump caused a partial vacuum at the hole so air was actually pulled in. Yes, the air was under a bit of pressure from the pump, but I think that pump was a volume and not pressure pump. IOW, it wouldn't provide much pressure to overcome the exhaust system pressure. However, this is just speculation on my part.

So, if it was just to provide a flat surface to drill then grinding the bump off would not cause a problem. But, if the height of the bump has meaning, as I'm sure it did, then grinding it off must cause a difference. What that diff might be I do not know.

Anyone?

Dunno, But I like the machinist idea about the drill bit not walking. But it could have been lower in the port and had the same effect for not walking. Having the hump taller would introduce the AIR into the port more in the center, close to the valve stem versus at the edge/side of the port. Could make a difference in mixing the air in....

I don't think it will make a difference in emissions after the fact. If the emissions was working to start with, this will have little to no effect. Especially since only 3 of the 4 were drilled to start with.......