porting s.p. heads?

[BFB]

any of ya'll ever do any porting and flow testing on single port heads? what was results?
one, im just curious and two, i got a buddy building a rat rod type vw and thinking about dual carbing a single port. i picture a retro 60's look with some long runners and tall velocity stacks, maybe not what he's planning but i think it'd look cool.
i know single ports aren't the popular choice ( which is another reason i like the idea ) but i remember seeing a few threads where stock s.p. was compared to stock d.p. and there wasn't much difference?
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[vwinnovator]

back in the '80's I ported a set of SP and ran a 34 pict3 (cut off the flange from a DP manifold and welded on to a SP manifold)

1600 SP w/stock cam and sig erson 1.5's

ran mid/low 17's in the 1/4 with a full body stock trans

you can get more from a DP, but sometimes it fun just seeing what you make out of scrap parts...

[mark tucker]

if you know what your doing yes they should work good, you can do a lot as with most heads.the better you are and the more equipment you have to do it with the more power you could see...if you know what your doing.and just want to.

[74 Thing]

Send them to Brian e or follow his advise outlined here:

https://www.thesamba.com/vw/forum/viewtopic.php?t=682243&highlight=

[Alstrup]

THAT.

[bugguy1967]

[modok]

I have only done a little with SP heads but what little I did worked nicely.
IMO achieving more flow though the port is only one piece of the puzzle, and only worth focusing on once all else is figured out and proportioned right.
the choice of cam, valve size, and seat angles is a slightly tricky thing because one runner feeds two valves.....the amount of overlap between those valves is important. Has to be enough, so so the runner can transition from feeding one to feeding the other with minimal interruption, but not too much. Too much then the intake flow during that period takes the path of least resistance instead of it going where you want it to go.

37mm valve is a fine size for the largest intake manifold it is possible to normally fit on the head. fitting a larger intake manifold might be as simple as boring the pocket larger, but I haven't done that yet.

[Alstrup]

[Erik G]

Any of you that have done port work doing 3 or more angle valve jobs? I'm thinking that would keep the air speed up? Instead of a bigger valve?
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[modok]

Of course.
If there is not enough room on the seat insert for what I feel are the correct angles, I consider that a problem, and find a way to fix it.

[spencerfvee]

[Brian_e]

I have posted these elsewhere before, but here they are again. I did them a long time ago, and they worked pretty good. Decent amount of work, but the engine drove pretty nice. I filled the copper sealing ring groove, and then made it larger diameter. I moved the mounting studs out, and made them 8mm. Then I made new tapered Kadron manifolds with the larger ID at the bottom flange. The engine was a 1915cc, stock crank, these heads, Web 218/119, 8.5, and a 1 3/8" header. Next time I would stick to a 1776, or 1835, and use a smaller cam. No more than 238deg @ .050".

In the end, they flowed about the same as a warmed up dual port head with the same size valves.
I still have the heads and manifolds, and I keep thinking I should rework them a bit and build another engine for them. A 37mm intake valve would most likely help. I have learned a lot about seat angles and valve jobs since these were done 8 years ago, and I know they can be made better now.

I have built a lot of quick easy single port heads since then, and following the link 74thing posted is the best thing to do for most guys. The valve job is VERY important, and the easiest way to see the biggest gains. A very simple 1776, 8.5, dolled up heads just like the other link I did, a cb2232 cam, kads and a header make for a great little engine. Easy to build, easy to drive, and relatively cheap to build.

Racerdave and Roy will be along shorty to tell us all how single port heads are a complete waste of time........😂😂😂😂🤦🏼‍♂️

Brian
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[Alstrup]

Racerdave and Roy will be along shorty to tell us all how single port heads are a complete waste of time........😂😂😂😂🤦🏼‍♂️

Hehe.

Wrt cam. I agree as such. It is VERY easy to overcam a sgl port. That said I have used up to 10 degrees split on some sgl ports. I built a 1914 several years ago (the only sgl port 1914 I have ever built, and will not build 94 mm bore sgl ports again for several reasons) That was for a split bus and on custumers reques.t Ended up with 6 degrees split, 0,010" difference in valve lift, and 110 LC
- Actually, in slightly larger than stock displacement sgl port engines w. dual carbs the Engle W100 cam works quite well. Also, in the same range, even stock carbed sgl ports controlled by a W90 works surprisingly well, - as long as you are not affraid of compression. - Not my favourite, but it deserves to be menthioned.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[mark tucker]

I think many single port intakes are too restrictive.duels&singles, you can over carb a intake&under carb the same engine.... personaly If I were to do a single port I would split the ports,make each bigger run a devider in the intake so it would now be a duel port...in single port clothes. if the fireing order was different the stock system would run beter with more cam.but it aint so it is what it is.( making a bigger single port looking manifold into a duel wouldn't be that hard to do.) or just stay with the single stuff and have a lopey idle...witch is what most want any way.

[vince1]

My first "Hi perf" engine was a single port 1776, fitted a Webcam 218 ground on 103 LC, kadrons with 32 mm vents, ran great.
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[Alstrup]

[BFB]

[Alstrup]

[FreeBug]

I remember some formula-V heads I once saw, the port volume was hogged out to become one big bowl, and the intake was welded up for a four-bolt flange to clamp the manifold onto. They were flycut like crazy, and were just one big crack.

[mark tucker]

with bigger valves always make sure the chamber is un shrouded. chamber shapes affect flow a lot more than most people think on intake and exhaust. most people dont have a clue what a port needs to flow better and just do some pretty look at what I did work....kinda like fake boobs..did the fake boobs for the real issues??probably not.
also....many people dont realize the chamber shape starts at the 45 degree seat. and that aera and the next 3/8-3/4" outward is very important to flow. just look at how flow increases as the chamber is milled. ad to that a proper shaped chamber and you have the start of a good head,untill know it all joe bubba type exspurt car club president machinist with his fully equipped machine shop( die grinder)gets a hold of it....in the dirt ..on the dirt floor of his shed trying to make some $$ so he can send his car to somebody to get it to start and fix all the effed up stuff.