How far can I go with the thermactor hump (porting)

[travis]

I’m sick of iron, and sick of Ford’s at the moment

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How much more, if any, should I take out on the flange side of the exhaust port guide boss?

Btw...it is absolutely ridiculous how much iron is in that thermactor boss.

Can I/should I square up that lower right hand corner of the exhaust port as well? That would actually be the left side of the roof if the head was oriented correctly.

[PRH]

I would think the more pertinent first question, before you even started whittling should be.......how good does it need to be for the application?

I’m assuming since there’s a hole there, that it’s drilled initially from the bowl area, and that it could be tapped and something threaded into it?

I’d probably try and use something like a brass screw(easier to grind) threaded way down into the hole........ and then grind away some of the sides on that boss, and leave the new screw material as sort of a vane.

No ford heads here to look at, so maybe that’s not really feasible.

[Carnut1]

I may knock the height down a bit but I never ground it out like that. I like a minimum of 2" of guide length. See if you can find a picture of a cutaway of that exhaust port on the web.

[travis]

The guide/boss is still stock...this is just the massive thermactor hump behind the guide

[Carnut1]

Sorry, I thought that was the valve guide you cut into. Which casting is this. You need sharp burrs and gorilla forearms to tackle them. Lots of grinding

[PRH]

With the typical street or street/strip stuff...... I go after the biggest gain for the least amount of work.

I’m not spending a bunch of extra time chasing down a few cfm.

[travis]

Sorry, I thought that was the valve guide you cut into. Which casting is this. You need sharp burrs and gorilla forearms to tackle them. Lots of grinding

Yeah...tell me about it...my hands and shoulders are f’n killing me right now

This started as a basic mild bowl blend...the intakes aren’t “terrible” looking for smogger junk, but these have the worst looking exhaust port of any head I’ve ever seen. I don’t know if it gained any flow but they are definitely lighter now

The guides, valves, and seats are in shockingly good shape for having a 1/4 million miles on them. But then again, 8.1-1 compression, a 195@.050 cam with .416” lift, and supposedly 210hp probably didn’t stress anything too much.

These will be going on yet another low $$$ 351w in one of my buddies cars...either a ‘82 LTD 4 door or a ‘80 or ‘81 mustang. The mustang has a 255 v-8 and something like 2.26 or 2.29 gears and a C-4...it is absolutely horrible

[travis]

With the typical street or street/strip stuff...... I go after the biggest gain for the least amount of work.

I’m not spending a bunch of extra time chasing down a few cfm.

That was the plan...quick bowl blend and short turn work and call it good. I should have stopped there.

[Walter R. Malik]

I’m sick of iron, and sick of Ford’s at the moment
0878B42D-1FE7-4086-A7EA-C0294CFF128B.jpeg
0CB9DD01-9226-416D-BF11-D43285991D95.jpeg


How much more, if any, should I take out on the flange side of the exhaust port guide boss?

Btw...it is absolutely ridiculous how much iron is in that thermactor boss.

Can I/should I square up that lower right hand corner of the exhaust port as well? That would actually be the left side of the roof if the head was oriented correctly.

About .060" before you hit water is the most you can go. Getting to that point is another question.

[PRH]

These will be going on yet another low $$$ 351w in one of my buddies cars...either a ‘82 LTD 4 door or a ‘80 or ‘81 mustang. The mustang has a 255 v-8 and something like 2.26 or 2.29 gears and a C-4...it is absolutely horrible

Sounds like one of those 1-1.5hrs per head jobs to me.

[travis]

I’m sick of iron, and sick of Ford’s at the moment
0878B42D-1FE7-4086-A7EA-C0294CFF128B.jpeg
0CB9DD01-9226-416D-BF11-D43285991D95.jpeg


How much more, if any, should I take out on the flange side of the exhaust port guide boss?

Btw...it is absolutely ridiculous how much iron is in that thermactor boss.

Can I/should I square up that lower right hand corner of the exhaust port as well? That would actually be the left side of the roof if the head was oriented correctly.

About .060" before you hit water is the most you can go. Getting to that point is another question.

Are you talking about the roof, or that corner (or both)?

I haven’t raised the roof yet...just kinda smoothed everything out, took a tiny bit off the short turn, whittled some off the huge intake guide bosses, and of course what I’ve taken out of the thermactor boss.

[Walter R. Malik]

Are you talking about the roof, or that corner (or both)?

I haven’t raised the roof yet...just kinda smoothed everything out, took a tiny bit off the short turn, whittled some off the huge intake guide bosses, and of course what I’ve taken out of the thermactor boss.

Both the back wall to the sides of the guide and the roof.
I have used a sonic checker to be sure not to go to far. Some ports are thicker than others.

Only go back to the rear of the actual thermactor hole if you are not sure
The photos you show is safe.

[travis]

Both the back wall to the sides of the guide and the roof.
I have used a sonic checker to be sure not to go to far. Some ports are thicker than others.

Only go back to the rear of the actual thermactor hole if you are not sure
The photos you show is safe.

Thanks Walter

[Joe-71]

It would be much easier with round stones and a high speed grinder such as a Dewalt. Gives a much nicer radius, better control of material removed. The E-7 style EGR hump can be nearly made flat with the roof if done properly in the bowl. Those ports can be brought up to 180 cfm without a pipe. Joe-JDC

[Carnut1]

I did a set of 289 that had that style exhaust port. I don't think it flowed 100 cfm stock. It got much better giving it some room around the guide and shrinking the boss a bit. Was not for a high rpm build, mild street 306.