Lookie what $5000 buys you....

[Kern Dog]

I pulled the valves out and took a look at the ports.

That ring below the seat..... My understanding is that anything sharp that is in the path of flow is a restriction.

Notice the irregular shape of the ring on this port above.
Intake port below. I see a bump to the left of the valve guide. I'm curious if the guide boss needs any smoothing since the flow comes in from behind it and not toward it.
I apologize for the blue shaded light but I needed some light for this picture:

I am running on common sense here since I have no experience with this. It seems to me that when porting, you need to look at which direction the flow is going. For exhaust, I think that smoothing out around the valve guide boss makes sense along with eliminating that ring below the valve seat.

I am using an air powered die grinder that I already had here. I may need to go get more bits though. On each head there 4 exhaust and 4 intake ports with inlets and outlets to grind on

 

[1 Wild R/T]

I pulled the valves out and took a look at the ports.
View attachment 950859
That ring below the seat..... My understanding is that anything sharp that is in the path of flow is a restriction.

View attachment 950860

Notice the irregular shape of the ring on this port above.
Intake port below. I see a bump to the left of the valve guide. I'm curious if the guide boss needs any smoothing since the flow comes in from behind it and not toward it.
I apologize for the blue shaded light but I needed some light for this picture:
View attachment 950861
I am running on common sense here since I have no experience with this. It seems to me that when porting, you need to look at which direction the flow is going. For exhaust, I think that smoothing out around the valve guide boss makes sense along with eliminating that ring below the valve seat.

View attachment 950862 View attachment 950863

I am using an air powered die grinder that I already had here. I may need to go get more bits though. On each head there 4 exhaust and 4 intake ports with inlets and outlets to grind on

It looks like someone put hardened seats in and didn't do a bottom cut to blend the new seat to the bowl....

You can see in the intake what typical blending is needed.. Those exhaust ports are worse than normal

 

[1 Wild R/T]

Smoothing, blending & narrowing of the guide is good, also throw a head gasket on the head, locate it with pins in the guide pin location & look to see how much the chamber overhangs the gasket along side the valves... That is shrouding & unshrouding the valves is beneficial...

 

[Kern Dog]

Looking at the valves, I can't see more than one angle on the back side. A single angle valve job?

 

[Kern Dog]

Smoothing, blending & narrowing of the guide is good, also throw a head gasket on the head, locate it with pins in the guide pin location & look to see how much the chamber overhangs the gasket along side the valves... That is shrouding & unshrouding the valves is beneficial...

I've heard of that. I'm guessing that in doing so, the chamber volume increases slightly but not enough to pose a problem if they all are shaped in a similar fashion ?

 

[Kern Dog]

The heads from my red car, "Ginger":

 

[Kern Dog]

Those same gaskets on a '346 head:

I guess it is fair to assume that there is no way that I could hog out these ports to the gasket size ??

 

[1 Wild R/T]

Those same gaskets on a '346 head:
View attachment 950870
I guess it is fair to assume that there is no way that I could hog out these ports to the gasket size ??

You could... But I wouldn't... Take the easy gains & leave the higher risk stuff alone.. Putting hours into a head only to have it leak water into the engine sucks....

Max ported 906's typically flow about what Edelbrocks flow OOTB so if you want that type of flow save yourself hours with a grinder....

But if your sticking to a budget a few evenings with a grinder is certainly worthwhile..

 

[Kern Dog]

Thanks. I'm not looking to hit it out of the park my first time at bat. Maybe I'll gasket match the ports to the smaller size just to be safe. I'm reading that the bigger gains are in bowl blending, right?
Any estimate on what the gains might be? It would be nice to have a ball park idea of the numbers. It surely hinges on cam, compression and other factors.
20 HP maybe? 30 ?

 

[1 Wild R/T]

20-30 is realistic, if you were dealing with a higher compression ratio & bigger cam it would be more but an extra 20 HP with a 9-1 440 with a 280ish cam & headers should make a pretty stout motor..

 

[Kern Dog]

Thanks. I'll probably use these heads on the .030 1976 440 I have with the 6 pack 2355 pistons.

 

[eldubb440]

The heads from my red car, "Ginger":

Maryanne is the one you marry....... but Ginger can remove the chrome from a trailer hitch

 

[Kern Dog]

20-30 is realistic, if you were dealing with a higher compression ratio & bigger cam it would be more but an extra 20 HP with a 9-1 440 with a 280ish cam & headers should make a pretty stout motor..

The Summit calculator shows me to be at 9.26 to 1 with 88 cc stock heads. These have been milled a bit, I'm guessing by the .077 depth of these chambers VS .101 and .105 of other heads in the shed, These '346s could be between 80-84 ccs. Figuring a 80 cc number and a block deck cleanup of .0005, I'd be at 10.01 to 1. Still not bad and also within the limits of 91 octane fuel.

 

[eldubb440]

I have a set of 915s ported with the big valves and a good bit of meat cut off........ .060 if i remember correctly, been a long time and would probably do things differently now

pistons are like .090 in the hole.......did the math, 9.5:1 I think

not sure what to expect, i just hope it doesn't ping

 

[Kern Dog]

Detonation does suck. If this one knocks, I could slip on another set of heads that are uncut with the bigger chambers OR some .060 Cometic head gaskets. No quench here anyway, right?

 

[1 Wild R/T]

The Summit calculator shows me to be at 9.26 to 1 with 88 cc stock heads. These have been milled a bit, I'm guessing by the .077 depth of these chambers VS .101 and .105 of other heads in the shed, These '346s could be between 80-84 ccs. Figuring a 80 cc number and a block deck cleanup of .0005, I'd be at 10.01 to 1. Still not bad and also within the limits of 91 octane fuel.

If your at 10-1 I would definitely un-shroud & open the chamber to the gasket then polish the chambers... If you add 2-3 CC's of volume to the chamber and remove potential hot spots you improve the chances of no detonation...

Is the area below the exhaust seat as ugly in person as it looks in the photos?

 

[Kern Dog]

No, aside from that sharp shelf below the seats, there is just the usual valve guide boss ridges and some small bumps. It looks like some blending is going to be beneficial.

 

[Kern Dog]

If your at 10-1 I would definitely un-shroud & open the chamber to the gasket then polish the chambers... If you add 2-3 CC's of volume to the chamber and remove potential hot spots you improve the chances of no detonation...

Open the chamber to the gaskets...
To what shape? Blend at an angle or cut it horizontally and make a 90 degree toward the deck/gasket surface?

 

[1 Wild R/T]

Open the chamber to the gaskets...
To what shape? Blend at an angle or cut it horizontally and make a 90 degree toward the deck/gasket surface?

Blend it down to the floor, unfortunately you can't un-shroud the valves as much as I'd like because you don't want to open the chamber up bigger than the cylinder bore.... Since you have extra heads I'd take a couple old valves & cut the head down so it drops further in the port but protects the valve seat...

Also when working the port I use a 3/8 bolt that I grind most of the head off to protect the guide....

 

[Kern Dog]

I have several old valves.....good idea.