SP SinglePort Heads P&P

xavi_242 · Posted: Sat Nov 12, 2011 1:09 am Post subject: SP SinglePort Heads P&P

OK so I'm looking for some nice info (and pics) about doing polishing & porting SP heads as I would like to do in mine.

I'm reading the Bill Fisher How to Hot Rod... and I found it's nice but sometimes it looks like quite demode... I read all on the singleport porting info and it's quite confusing and black and white pics don't help at all... plus english is not my 1st language... so imagine.

Bill Fisher says that that just removing material from what it 'looks like air will flow better' doesn't always work and give some hints in his book... I didn't understood at all..

I've found a lot of info about P&P DP heads but not many about doing it on SP ones... ANYONE can help me? Threads? PICS? LINKS?

I've also found some threads that mentions it but nothing specially focused on that topic.

http://www.thesamba.com/vw/forum/viewtopic.php?t=477867&start=49 what I've found this thread to be the best one showing pics of a P&P (at least polished) SP head...
http://www.thesamba.com/vw/forum/viewtopic.php?t=483917 DIY P&P nice info but mostly for DPs
http://www.thesamba.com/vw/forum/viewtopic.php?t=446734 some SP porting info

THANKS!
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1967 Split SO-42 Dormobile

mark tucker · Posted: Sat Nov 12, 2011 9:32 am Post subject:

most all heads react to the same things being done.with that said I have never had a set of single ports in my hand.do you have to stay with single ports? at 1 time I was thinking about doing a set of them,but havent done so yet.

xavi_242 · Posted: Sat Nov 12, 2011 11:19 am Post subject:

ralf · Posted: Sat Nov 12, 2011 12:16 pm Post subject:

i have a bit of updates on my thread, that you have linked up...

wat sort of help do you need mr. xavi alonso LOL!
_________________
Flow Through a Curved Conduit

porting my SP head for my brother's project
https://youtu.be/OS_mVjQuqgk

modok · Posted: Sat Nov 12, 2011 2:12 pm Post subject:

What CCs and RPM range?

xavi_242 · Posted: Sat Nov 19, 2011 2:48 pm Post subject:

I'm building a 1776 and want to keep SP because I got a NOS EMPI manifold, Zenith 32 NDX and a Bosch 010 distributor like the kit Empi offered back in the day. I love the blue SP manifols and want to go SP, I know I am loosing some ponnies but it is my choice and it is already made...

CR... from I calculated 9,4:1...? I guessed deck height and combustion chamber volume and probably is less because of the little valve unshrouding I'll do after oppening heads for the 90,5s... engine will go in my 67 westy W/swingaxle tranny.

So today I started with the mexican SP heads I got. Tom Wilson and Bill Fisher's books says that 1500/1600 SP heads changed over the years... seems that this is an upgraded version as there is no (or very very short) intake guide boss...

I don't want just fancy and shiny ports so I followed Bill Fishers book instructions and didn't did any personal contribution to this work as I'm a novice...

Image may have been reduced in size. Click image to view fullscreen.

from combustion chamber side intake port: radiused under valve seat into port runner (center). Removed casting seam (dotted line)

Note sharp edge under valve seat befr work is done

From manifold side: Enlarged a little port entrance (was 30mm) till old gasket edge, removed casting seam towards exhaust side (dotted line) and radiused sharp edge towards top.

more to come...
_________________
1967 Split SO-42 Dormobile

Micropassatman · Posted: Sat Nov 19, 2011 2:56 pm Post subject:

Looking good! This is EXACTLY what I need to lok at before I attempt this on my own S/P heads. I actually need a second set of unmolested 311 S/P heads to try this on so I have a good backup set. Velocity rules!

mark tucker · Posted: Sat Nov 19, 2011 3:07 pm Post subject:

a lot of what I have seen in that book is rong,including a lot of the porting&chamber mods.

xavi_242 · Posted: Sat Nov 19, 2011 3:12 pm Post subject:

ralf · Posted: Sat Nov 19, 2011 3:22 pm Post subject:

xavi , on ur last pic... do not remove much material on the short turn of the roof..

yes in ordinary sense it would make sense to shorten them

but if you try to "feel" the ports, and have a cut away view (even if just imagination) that short turn is sooo abrupt...

you may need to actually enlarge the entry (like in my thread) to give you more freedom to contour the short side radius into a bigger more gentle radius/curve

on your 3rd pic, try not to cut too much out behind the guide

it will add dead spots as there is much less flow there due to the routing of flow from the guide,

you can enlarge it.. if you do go to a bigger valve/seat Smile

_________________
Flow Through a Curved Conduit

porting my SP head for my brother's project
https://youtu.be/OS_mVjQuqgk

Rome · Posted: Sat Nov 19, 2011 3:28 pm Post subject:

Good so far. In your second-last photo, I'd shave off material from the "ceiling" of the intake port to reduce the gentle "S"-bend. Just work material off from where you have the two top arrows, working back into the intake port.

If you're going for 1776cc with the 90.5mm cylinders, you can also do some minor valve unshrouding in the combustion chamber. Place the 90.5 cylinder into your head, then make a sharp trace along the inner diameter of the cylinder so that you can see the outline on the head, and see how far you can remove material outward of the valves. This detail is also covered in Fisher's book.

As a side benefit, this unshrouding process lowers your compression ratio because you are removing material from the head, increasing your combustion chamber volume. So when you choose your cam and reconsider your 9._ compression ratio, knowing your chamber volume you can then calculate what thickness shim you need under your cylinder to get a good deck height and your desired compression ratio.

ralf · Posted: Sat Nov 19, 2011 3:33 pm Post subject:

mark tucker · Posted: Sat Nov 19, 2011 3:39 pm Post subject:

kinda hard to explain but I got a big laugh years ago when I read the book.
kinda think of it as a watter fall ,as the water flows over the edge of a round port the sides restrict the flow in the turnand try to throw the flow to the center more or over a hump,square out the short side radi. if you dont understand think "D" port with the flat on the short side,but it is only widened & raidust not angled down to the seat, gentle turn. look up some small block chevy aluminum heads and you will get the idea a little better

ralf · Posted: Sun Nov 20, 2011 1:40 am Post subject:

Xavi , just always remember flow or current will always be faster on the short side radii vs the long side radii (radius) so in our sp case the roof/top is ths short side radii ,

The bigger speed/velocity difference on the short side vs longside will cause a sheerig effect which is no bueno as far as flowing well goes ,

On dual ports it is why some has the venerable D shape entry

On our sp it is a lil bit different , just a little bit

The D shape still helps as ur widening the short side thus slowing it enough to come close to the long side's speed , making it more uniform so to speak

But be careful following "looks" if u make the entry D then u could possibly creat a narrowing effect as u enter the short side , making this faster and causing a bigger delta in velocity , if you do the D make sure to widen the inside roof too ,

U can make it easier by jist increasing the diameter of the entry to 34mm
And widening the short side (inside) to slow the speed down...

The d is a good shape though , but just remember wat u see in the pic and copying just the entre wont do much...

Il try to post pics to give u more visual aid

Ralf,
_________________
Flow Through a Curved Conduit

porting my SP head for my brother's project
https://youtu.be/OS_mVjQuqgk

xavi_242 · Posted: Sat Nov 26, 2011 12:32 am Post subject:

Thanks everybody for your inputs!
Just worked more on the intake as per your advices. This is my work bench.... sorry my work DESK! Smile

I opened the entrance to 31mm (I started with 30) and I'm in the gasket edge so I'm not going to go further... I don't understand how ralf opened his one to 34mm... maybe his head is different. If I open it to 34 then I only have 1,5mm around the hole to lay the gasket... too little I think.

Then I worked a little bit on the upper sides from manifold just to start feeling a D shape. But just a little bit, nothing major. No pics cause not noticeable...

Started then with exhaust. Pretty much easy as exhaust port work kinda well alone from what people says. So I just radiused under the seat towards header because there is a 90º straight edge and trimmed the guide boss (see arrows).
Note in the picture how the effective section is enlarged just by doing that 2 operations (note height arrow on right worked port)

A pic from header side.

Bill Fisher says to don't remove the bump/edge just under the seat, towards intake valve seat. There is like a scoop that helps air to sort the 90º guide boss interference. So I left there. See dotted lines.

Hope you liked.
_________________
1967 Split SO-42 Dormobile

ralf · Posted: Sat Nov 26, 2011 1:10 am Post subject:

Xavi , i opend mine up and ur right it should/does have about 1.5mm ledge left

Wat i will do is i jave two options
Taper a little bit the sp manifold's mating throat, this way using the steel gasket ring , the maniflld will naturally push it out to the wall as you tighten the manifold to the head Smile

The other option is... Cut a ridge around the manifold's throat
And put a copper oring Smile

this way the sealing mechanism is built in to the manifold Smile

_________________
Flow Through a Curved Conduit

porting my SP head for my brother's project
https://youtu.be/OS_mVjQuqgk

xavi_242 · Posted: Sat Nov 26, 2011 1:31 am Post subject:

Hi Ralf!
I have an issue and is that the manifold I'm going to use is currently mounted on my dialy driver and it's pretty hard to remove...

So I'm not going to do a propper match porting before head assembly...

Thanks for your comments, though...
_________________
1967 Split SO-42 Dormobile

ralf · Posted: Sat Nov 26, 2011 1:36 am Post subject:

Its okay, just make sure when u install the manifold to the new head, make a pass with the grinder using some sanding rolls, to give it a little taper so it can push out the steel gasket ring when u use them , u may be okay with ur ports now, mine im changing valveseats and going bigger valves so i opend the entry a bit

My head has the 311 373a casting on it , its the 1500-1600 sp head
That has the same valve size as the dual port 040s 35.5x32

So i think we have the same head Smile

_________________
Flow Through a Curved Conduit

porting my SP head for my brother's project
https://youtu.be/OS_mVjQuqgk

modok · Posted: Sat Nov 26, 2011 1:58 am Post subject:

You also have the same one angle valve job Laughing

But that's gonna change I'm sure.......

Looks fine BTW, I bet it will run a little smoother, a little port work is never a bad idea.

With that intake and being SP, keep the cam mild, if you want to get more rpm and run more CR, it may be better to retard the cam a few degrees rather than choose a bigger cam.

ralf · Posted: Sat Nov 26, 2011 2:38 am Post subject:


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