Porting suggestions/pics for 3x00 heads

[ForcedFirebird]

Got my gaskets finally, and will start porting this weekend. I was fitting the gaskets on and noticed two surfaces of the heads lined up with the gaskets.

I'm planning on a gasket match, but was unsure on a couple of things.

1. Are you guys removing material from the port floor/wall? It looks like a little can be removed to make a more direct shot to the valve.

2. Has anybody ported to the carbon stains around the exhaust ports? I've seen pics of some of your portings, and nobody has gone that far.

3. How large should I go? I'm planning on using Camaro 3.4 pistons and 3500 heads to get up and running again, but then switching to 3400 pistons to re-boost the car, which leads to my next questions:

1. When modifying the chambers, I see the valves could be slightly less shrouded as there is a little material, almost like a lip, up against the valve. OK to remove?

2. The large area around the sparkplug, should I just smooth the edges here?

3. The sharp edges on the heart-shape, OK to remove?


And one more not totally pertaining to my 3500 heads. What do you think the effects would be if I wrote a CNC program to remove material from 3400 heads, in the same shape/size as the head gasket to lower compression for some RWD friends of mine that are scared to do the swap because of having to change pistons?

Pics/suggestions would be greatly appreciated!

Here's the wall I'm talking about...



Here's the floor I'm talking about...


Here's the carbon ring I am talking about around the exhaust ports, since I am making my own headers/flanges, but just don't know if that's overporting?...

[SappySE107]

1. Are you guys removing material from the port floor? It looks like a little can be removed to make a more direct shot to the valve.

no

2. Has anybody ported to the carbon stains around the exhaust ports? I've seen pics of some of your portings, and nobody has gone that far.

don't.

3. How large should I go? I'm planning on using Camaro 3.4 pistons and 3500 heads to get up and running again, but then switching to 3400 pistons to re-boost the car, which leads to my next questions:

not at all

1. When modifying the chambers, I see the valves could be slightly less shrouded as there is a little material, almost like a lip, up against the valve. OK to remove?

no

2. The large area around the sparkplug, should I just smooth the edges here?

if you really want to.

3. The sharp edges on the heart-shape, OK to remove?

Just deburr.

[ForcedFirebird]

So basically just gasket match and remove casting irregularities, debur the chambers, and call it a day? That just sounds too easy (not like some SBC stuff I have done).

Same with the manifolds? I plan on getting them mirror smooth before the injectors, and 80grit after - good?

[SappySE107]

Don't gasket match the heads to anything (other than intake top and sides). Surface texture is up to you on the intake.

Did you do any flowbench or simulation research on the SBC heads you modified?

[ForcedFirebird]

Did you do any flowbench or simulation research on the SBC heads you modified?

No I'm a redneck, just copied what others were doing that had good results. Made a difference in E.T's, that's all we cared.


What kind of bench do you have?

[SappySE107]

home made with flowquik.

[IsaacHayes]

You could polish the combustion chambers?

[3400-95-Modified]

Bling bling...


I know I didnt do enough but it looked sweet...

[IsaacHayes]

Jon, it may not be perfectly smooth but the casting texture now has smooth edges instead of rough sharp pointy ones. I would think that would help with hotspots too.

[MY91GT(Z)]

what do u polish the bowls with and how far do u recommend goin on the bowls and what r the advantages other than the hot spots

[ForcedFirebird]

Chambers down to 80 grit is my plan, I will also be removing a little material to get the compression down just a tad.

[Monzsta]

Got my gaskets finally, and will start porting this weekend. I was fitting the gaskets on and noticed two surfaces of the heads lined up with the gaskets.

I'm planning on a gasket match, but was unsure on a couple of things.

1. Are you guys removing material from the port floor/wall? It looks like a little can be removed to make a more direct shot to the valve.

2. Has anybody ported to the carbon stains around the exhaust ports? I've seen pics of some of your portings, and nobody has gone that far.

3. How large should I go? I'm planning on using Camaro 3.4 pistons and 3500 heads to get up and running again, but then switching to 3400 pistons to re-boost the car, which leads to my next questions:

1. When modifying the chambers, I see the valves could be slightly less shrouded as there is a little material, almost like a lip, up against the valve. OK to remove?

2. The large area around the sparkplug, should I just smooth the edges here?

3. The sharp edges on the heart-shape, OK to remove?

I don't know about anyone else, but I've never been able to "over port" a head, unless you hit water, of course.

Not to sway your judgement but I went friggin' nuts on my 3400 heads.

I cut the exhaust port all the way to the gasket edge, smoothed the bowl, straightened the dog leg a bit, cut the chamber wall out to the fire ring to deshroud the valves, ground down the guide bosses, and killed the hump in the intake port and the chamber near the plug boss. The port and chamber looks beautiful, and should flow well. More power will be gained by increasing port flow and stabilizing combustion by deburring then by the CR increase from the small amount of metal you remove. Less detonation = more timing.

Do I have a flow bench? No. Have I ported a stock engine to 1st place in a few circle track races? Yes. Air likes a straight shot and long radiuses.

Being it's port injected, the fuel is shot at the intake valve, so fuel suspension is moot. Finish isn't really relevant to bulk flow, so I'm content with carbide dimples and a sand roll finish.

Will I never be able to utilize the flow I created? Maybe. But the ground work for a large cam and/or boost has been laid.

Just my .002 ppm

[ForcedFirebird]

I don't know about anyone else, but I've never been able to "over port" a head, unless you hit water, of course.

Not to sway your judgement but I went friggin' nuts on my 3400 heads.

I cut the exhaust port all the way to the gasket edge, smoothed the bowl, straightened the dog leg a bit, cut the chamber wall out to the fire ring to deshroud the valves, ground down the guide bosses, and killed the hump in the intake port and the chamber near the plug boss. The port and chamber looks beautiful, and should flow well. More power will be gained by increasing port flow and stabilizing combustion by deburring then by the CR increase from the small amount of metal you remove. Less detonation = more timing.

Do I have a flow bench? No. Have I ported a stock engine to 1st place in a few circle track races? Yes. Air likes a straight shot and long radiuses.

Being it's port injected, the fuel is shot at the intake valve, so fuel suspension is moot. Finish isn't really relevant to bulk flow, so I'm content with carbide dimples and a sand roll finish.

Will I never be able to utilize the flow I created? Maybe. But the ground work for a large cam and/or boost has been laid.

Just my .002 ppm

Pics?

That is the thinking I followed on the SBC iron heads. This is the first port job on both aluminum and v6 heads, never modded a 60* until I got this car.

I can tell you that what I am strting with is a lot better than we had sometimes ended up with after porting.

I plan on taking full advantage of the flow on theses heads. I'm going all out on this build, and will be boosting to the limits of the stock 3.4 bottom.

[SappySE107]

All I can do is give advice. I have done more than flowbench work to determine how I port these heads. If you do the same with 3400 heads and 3500 heads, I promise you will have fucked your 3500 heads up. Ill put money on it.

[ForcedFirebird]

All I can do is give advice. I have done more than flowbench work to determine how I port these heads. If you do the same with 3400 heads and 3500 heads, I promise you will have fucked your 3500 heads up. Ill put money on it.

Not mine! I will listen to someone who has worn the path before me.

My only problem, Ben, is you keep showing/telling me all this cool stuff that I can have at the shop for this and future projects. Things that I probably shouldn't be buying, like flow bench parts/burette (buret).

No more red-necking here .