Need Help- Porting Heads for beginners

Chris the picture I posted was of a Intake port, so sorry I should have been more detailed in my last post.
Here's some pictures of a near done Exh port in that head but for a good polish job
Note that this heads Exh ports are cast with what I call a kick over down the bowl on the Intake valve side of the Exh bowl.

This helps to guide the flow to the cylinder wall side of the bowl.

Note how in the last picture that the floor is wider then the roof path by a touch.

Once the flow gets around the short turn to its apex then at that point the roof needs to get wider and the floor should not be touched for any reason but to apply a polish to get rid of any ruffness.

This head happens to have a deep valve bowl so both sides of the guide got boatailed with no loss of low lift flow.
I sent you a pm with my phone number so call me and I can help you far faster then on here and also tell you how to make templates to guide your rework.

 

Thanks Steve, you said after Sunday so ill call you during the week to chat. Where do you get your carbide burrs?

 

Burr wise I have got some 80% of the 18 I own from a tool supply fellow who is at all the local auto motive flea markets around my area in the Summer and at great prices to boot!
the others I have got from cylinder head abrasives , or CHA for short.
The great thing about working on cast iron is you can use grinding stones which when shaped if need be on your bench grinder will give you the curve / radius you may be needing to grind into a port area.
You can see such in these photos.

 

I found a lot on ebay for cheap but no idea if they are junk or great. Don't you go through grinding stones fast?

 

I only use them for certain work ( not for large amounts of removal )and only in my 12,000 rpm cable driven grinder, not my 25,000 rpm grinder.
Also the red colored stones as compared to gray ones last longer and or remove metal faster if find.

 

Im getting these short burrs, but I need long burrs as well, do you find yourself needing a whole set of long burrs?

https://www.amazon.com/gp/product/B013WHOEMW/ref=ox_sc_act_title_1?smid=A3ECBC4XZ5SVQN&psc=1

 

Those are not that great. Like the ones from eastwood. They dull quickly. I bought many burrs from this seller from Ohio on eBay. Here's one I bought. Did probably 4 sets of heads using the same set of quality burrs. The 6" are about 20+. These fine burrs work on cast iron and aluminum if you keep the rpm down. u//m.ebay.com/itm/Carbide-Burr-SC-3-Cylindrical-Ball-Nose-Single-Cut-1-4-x-3-8-x-3-4-x-2-1-2/381921836318?hash=item58ec50bd1e:g:WP4AAOSwpDdU~fjD&_pgn=2&_nkw=burr+3/8+&_from=R40&rt=nc
Ray

 

Thank you Beast for the heads up and the seller

 

For polishing the exhaust runners and combustion chamber, what type and shape of stone works best?

 

Your just wasting your time in the chambers if there no sharp edges to be dealt with like most times only at the lip of the chamber or around the spark plug threads.

In many cases chamber wise small bumps help to brake up wet flow rivets that take way power and wash needed oil off of the cylinder walls if the stream continues on out of the chamber, and this can all lead to rich looking plugs.

But with either ( chamber or Exh ) if you feel you must I start off with a 40 grit sanding roll of either a taper shape or straight and then go over to a 80 grit or 120 for a final polish.

Another option for bowl or runner work is after ruff cutting to use a fine cut metal Burr ( for cast iron work only!) this will leave a finish that needs little polishing such that a 120 grit roll is all you need.
Even with a 80 grit roll you can get a finer polish then its 80 grit rating if you move it fast and both left to right and back & forth once you get it to show a polish.
It's kind of like when they mow lawns in across or X pattern the cut it finer even though the same mower and blade was used!

My process for the Intake ports is to 1) ruff cut, 2) fine Burr cut , 3) polish and final blend and then go back with the fine cut Burr to leave that type of textured finish.
Here's a example of a final fine cut finish on a Intake port, close to polish but not quite!

 

What shape long burrs do you use Steve? I want to buy My first set of burrs and there's a lot of shapes to choose from.

 

For starters a long type ( 6" ) Foot ball shape can be used for many grinding uses in both forward and back pulling motion and its taper can get you into tight spots, then round headed straight sided cutter is good and then a 1/2" diameter cone fast cut Burr is good to have.

Tomorrow I will post a picture of all the ones I have that get the most use.

 

In my attached picture, I find the second bullet to be very confusing. I see people use terminology vaguely when it should be very precise. Which part is considered the crown? And is that second bullet even correctly stated?

And in the first pic is the bowl area over exaggerated?

Sorry, I just need precise details on this stuff so I don’t mess it up. And using terminology interchangeably just confuses me. Or maybe I’m just confused. Lol

 

I thought we where talking in terms of Buick iron heads which are neither Hemi type or highly down drafted as in the two photos in your post.

In these two diagrams you can clearly see the details of the port I have been speaking of and if you are sharp with easy math you can see how the dimensions shown in the second diagram relate to the shape and size of the overall port which is all based off of the valve bowl Throat diameter and how any given port is Geometricly designed.

In either of these diagrams you can clearly see the apex / tall point of the short turn .

The Chevy Intake port in diagram 1 has a 23 degree valve inclination angle so the high point of the short turn / floor is long.
In the second diagram your looking at a Pontiac Intake port which has a 14 degree valve inclination angle and as such the apex / high point of the short turn is very definded !

The Throat diameter needs to be atleast 85%!of the valve size used if you want to max out high lift flow out of any given valve size!

 

Ha... funny.... yes Buick! But I couldn’t find a nicely used Buick head cross section That was already labeled, so I picked what was available. I think i have an unlabeled one, i May Mark it’s up tonight and see what you think. With that said, I’m still confused on some of the other percentages listed when the talk goes beyond the throat and valve size ratios.

 

Ok, lets talk Buicks!

 

A picture of your set would be great, thank you Steve!

 

I am sorry gang but I have no Buick heads on hand right now to show you rework on , but the 4 photos Matt posted are way better at showing what's going on in stock form at least with that Buick head casting.

When you look at the cut away of the Intake casting note how big the basic runner is ( except at the push rod pinch point near the flange) and how thin the roof is.

Next you can see how roof necks down to the Throat in the valve bowl of 1.66" or so which makes for a valve to Throat percentage of 83 which is pretty good for a stock iron production head of any brand!

In this casting when staying with the stock 2.00" doing work to the valve bowl other then very light blend will by you nothing really, the restriction is the big Webb of the valve guide support on the Exh valve side of the bowl.

On the Exh side there's a nice Venturi going on as formed by the valve seat and the start of the valve bowl.

As with castings like this with a short depth valve bowl which makes for the need of a quick short turn we need to make the short turn wider and flatter and yet still Venturi shaped and also to trick the flow into thinking that the short turn is taller then it is.
Once the floor gets up to the apex the floor widening should taper off fast as at that point at high flow rates the mass of the flow rides on the roof and any added floor width will only make for reversion, ruff idle and delayed throttle response

In increasing the width of the short turn should be done only on the cylinder wall side of it.
Making the rear wall of a short depth valve bowl like this wider as it approaches the valve guide on down from the seat will pick up high lift flow , but at the unacceptable loss of low lift flow.

In Chevy port diagram by David Vizard that I posted yesterday the A section when flow tested stock as a separate section can flow 270 cfm, the B section can flow 225 cfm and the C section with the valve at some .300" lift will flow about 112 cfm.

With the Chevy port there's a lot to gained by reworking the valve bowl, but this is not the case withthe head casting Matt so kindly posted.

Air flow like a stream of water will always try and take the path of least resistance ( straight line or the least bent) which on most heads takes place up to .300" of lift, after that as the level of air mass going thru the port increases and along with that velocity, the flow is more and more forced to follow the shape of the basic port instead of taking the center line of the port / path of least resistance.

Away here are some photos of my most commonly used Burrs on the left and then 3 other kinda special use ones.

 

Thanks for the pictures Steve, I dont see a cylinder style burr. Wouldn't it be easier to use this for the port sides and roof for a nice flush finish? (Picture attached)

And can you give some insight about what speeds you operate the die grinder at when doing this work?

 

No ,it would not without question!
Yes it would remove meat fast but the deep groves it would make would be Bitch to get out!
That type of Burr is good for removing casting flash be it sticking out in a bowl or castings Seams .
I use a ball head Burr, or one like the second or fifth Burr from the left in my last post.