SP SinglePort Heads P&P

[xavi_242]

finished the porting work after removing the valve guides...

intake:

exhaust:

Now time for the guides to go in...
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1967 Split SO-42 Dormobile

[xavi_242]

marked the inner cylinder walls on the heads

then draw the area to unshroud

it took me one hour per chamber... tough work!

and the final result, note that I am very conservative...

BTW on the exhaust side of the right chamber, not the small scratch from the dremel tool. There's half of the sealing surface intact, the other half is scratched, not too deep, noticeable, though.

My plan was so just put some fine lapping compound on the cylinder sealing surface and rub a little bit the cylinder against the head, just to smooth it a little bit. I was planning to do that on all 4 cylinders, not just on the scratched one.

What do you think?

Thanks!
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1967 Split SO-42 Dormobile

[xavi_242]

[mark tucker]

get a set of good twin port heads.scat has some prostreet heads that are midely ported and ready to go, perfect for this type of engine.

[xavi_242]

[Alstrup]

Have you assembeled the case yet?

- I have used the 2232 in dual carbed sgl port engines a couple of times. I found that it provided good torque, but the engines were a bit short breathed, like 4300 rpm, - end of story. So I decided to go 2239 on the next build, which - did - create a slightly rough idle, but gave me more power above 4000 rpm.
Depending on what youtre after, you might want to take that into consideration.

T

[FreeBug]

remember, the exhaust is like on a dual- port, so to keep an interesting inlet to exhaust ratio, concentrate your efforts on porting the intake. Exhaust maybe just polish to reduce heat absorption, don't over-port it.

[xavi_242]

so... after a loooong time I took again this project and took odd the heads from the shelf (they where literaly part of our book shelf at home) and started the work again.

Got the head from the machine job, now the 90,5s just slip in very smooth

This easter holidays I'll finish the porting job and then the 3 angle valve job...

more to come!
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1967 Split SO-42 Dormobile

[xavi_242]

[ralf]

Opposite the bowl (guide side wall) the side that joins the other port , clean it up and contour it from the chamber side
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Flow Through a Curved Conduit

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

[xavi_242]

[ralf]

Sounds good, for the cam and comPression , it looks like its gona be a decent street engine just do a few more clean up on the intake , more so on the inner walls of the intake coming from the chamber

This will naturally shape the divider in a more profiled manner but dont take too much material out
_________________
Flow Through a Curved Conduit

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

[xavi_242]

3 anlge valve job is what it's going to be happening, that's for sure.
I'm going to run a CB 2232 cam and a 8 CR...
http://cbperformance.com/catalog.asp?ProductID=1244
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1967 Split SO-42 Dormobile

[ralf]

[modok]

You also have the same one angle valve job
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]

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
_________________
Flow Through a Curved Conduit

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

[xavi_242]

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...
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1967 Split SO-42 Dormobile

[ralf]

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

The other option is... Cut a ridge around the manifold's throat
And put a copper oring this way the sealing mechanism is built in to the manifold
_________________
Flow Through a Curved Conduit

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

[xavi_242]

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

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.
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1967 Split SO-42 Dormobile

[ralf]

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,
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Flow Through a Curved Conduit

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