Head porting question

[Pablo]

I'm in the midst of porting my heads and was wondering if anyone had any idea what to do with the hump on the outside bottom corner of the intake port just before the bowl area.

Seems like it would be an impediment to flow, should I get rid of it or should I leave it alone?

 

[J-B Racing]

You can Port it down to a limit. Without an Ultrasonic you can go into the Water Jacket. Just don't go down too much to be safe.

 

[Pablo]

Thanks Joe

 

[turbofabricator]

The intake port floor can be lowered approx. .100" with out too much trouble. I have never broken through the port floor of a 8445 head. The valve bowl and seat is where 80-90% of gain is to be had. On the back side of the valve guide (vg) grind a large radius behind it on the biased side of the port. THe factory has a radius already there, just enlarge it after you narrow the guide and taper the leading edge of the vg. Look at it this way.........if you were air, how would you want to go through the port. No sharp edges, and lay a nice radius on the short side. There is not alot of material available for a good short side, though. I would suggest having a good three angle valve job done by a competent machine shop, and then port the valve bowl to .10 of the lower angle and radius it carefully. Then either have them touch the seats again, or if you were REALLY good with tool control, you can just lap the valves in place. Check the valve seats with a magnifying glass after you lap them for ANY low areas that you hit with a sanding cone or carbide. Use machinist dye to see the seat angles while lapping. (a red or blue Sharpie pen will also work.
The side of the bowl opposite of the biased side (the narrow side of the bowl/guide wall) needs to be opened up to about 3/8" and brough up (or actually down from the porters point of view) to the port roof. Widen the short side radius but leave a good radius on the "lump" of the short side corner. There IS water to be hit there. Just make a large radius where the lump is. You can hit water if you take it too far. Some heads can take a complete lump removal, some can't.
I have pics of a 8445 all cut apart if anyone is interested. There is alot of material that can be removed from most heads, but not all. Core shift detirmines how far you can go. If you have access to a power hack saw, and have an extra 8445 casting, you can learn ALOT by cutting one into pieces. Well worth the cost of a core. Take your time and study porting theory on gofastnews.com, and speedtalk.com Good luck.

 

[Pablo]

Ken,

Thank you for the highly informative post.

As far as the radius on the biased side of the port, do you mean so that it sort of curves around the valve guide? I found pictures of various ported heads before I started and saw some champion heads were done this way. The valve guide ends up being shaped like a number 9, or one half of a yin yang.. is that what you are talking about?

As for the valve guide boss, I've looked at some high end LS1 heads and saw something interesting. They basically knife edged the guide boss and the edge seemed to face the opening of the port. Looked like they were encouraging some flow to the inside roof next to the VG. Do you see any advantage to biasing the flow by reshaping the VG boss to the high flow side? Hope I'm making sense.

Another q, you say you have removed .1 from the floor of the port. I thought removing material from the floor was a no no, how did you go about doing this? A constant amount up to the short side radius? or did you just remove from the short side hump and tapered accordingly?


I would really like to see the picts of the head all cut apart. I have some picts that are posted on GNTTYPE.org but the more the merrier. I have a stack of printed pictures sitting next to me as I port for reference.

Did a set of heads for my SBC about 10 years ago so its all coming back to me slowly, fun fun fun

 

[rw87tt]

turbofabricator, I would like to see pictures too.

 

[Pablo]

BTW turbofab. Thanks for the link to gofastnews... David Vizard's books are awesome and it's great to see he is giving out info on the web.

The home made flowbench setup is unbelievably simple yet effective! I want to build one now.. hah, thanks for giving me another project.

 

[ijames]

Pablo, if you can find a copy of the Buick Power Source Manual they have pictures and porting templates for the stock heads. Hmm, wonder if someone could scan them and post them either here or to the gnttype web site? If someone does, I recommend they add a little ruler or draw a line of known length so any scaling in the scanning, printing, or copying can be taken into account (that's why I did that on the THDP template). Ken, any opinions on how those compare to what you do, or what current commercial heads like the Champion irons look like?

 

[turbofabricator]

Port volume is king on a turbo car, especially in our little ports. Removing material on the floor usually doesn't hurt flow bench numbers (alot), but helps on a boosted application. I will try and post some pics of the head tonight. On serious heads, I also take the port wall out into the head bolt hole and sleeve it (and the push rod hole) with a brass sleeve epoxied in place.
Yes, making the intake guide look like a number "9" is the idea. Good analogy. That picks up alot of flow. You might want to buy a 8445 casting and intentionally find water. It is cheap R&D. I just recently threw out I think 4 sets of 8445 heads that I had ported too far over the years.

 

[Pablo]

Turbofab,

about the non biased side next to the VG, you said to bring it up to the port roof. Should I take that to mean that I should raise it to be level with the biased side? I was going in that direction but it seemed like a pretty good chunk of material to remove so I took a break.

Btw, I have two sets of heads so I am prepared and willing to push it. Only downside is wasting all the time on a head if I break into the water jacket.

 

[turbofabricator]

There is 'usually' enough material there to trim the guide (narrow it) and use a 3/8" oval burr to take the remaing port wall and roof pretty close to level with the biased side. I've never hit water there, even after completely removing the valve guide boss level with the roof. (intake port roof, not the roof of the shop ) I completely remove the exhaust guide boss, too. THe exhaust side is where I hit water most often. The back side of the valve bowl is pretty thin. Don't be tempted to go too big under the valve seat. Some heads get real thin there, others don't.

 

[Pablo]

Thanks ken,

Your insight has been quite helpful. I will go ahead and raise the non biased side a good ways. BTW do you see a good flow gain removing the VG boss entirely? I'd like to keep some velocity to aid in spoolup, so I'm hesitant to remove too much.

 

[Jerryl]

Port volume data

Anyone have the port volume numbers for Champion Ported or other ported irons?

 

[blackgn1]

I believe that the intake flow is 209 cfm at 50 lifton the Champions.

 

[sweetv6]

some interesting pics

claude

 

[charlief1]

Great pics sweet. It helps. I'm getting ready to do mine soon.