porting a head DYI, need some direction Options

[02loftsmoor]

Jake see what happens when there is know one to watch us,, keep the matches and Scissors put away

[Mark Henry]

(IMG:style_emoticons/default/rolleyes.gif) Peeps love to make things seem harder than they really are, a mild P&P is not rocket science. The big part is having a die grinder thin enough, long enough and the correct tools.

Unless you plan to totally alter the port shape you don't need a flowbench. Don't worry about the intake they are plenty big enough. Don't go crazy removing material and do not remove the guide bosses. The exhaust just clean up the flash and polish smooth. Experience and common sense helps.

BTW did the seats and P&P on my 44X38mm 2.0 heads for my engine, I've also used HAM heads (forget number, but one below the top) on almost the exact same engine combo. By the seat of my pants I could see no difference in power from to two builds. On a dyno I seriously doubt any more than a 10hp difference between the two engines and that could be chocked-up to just the different exhaust systems.

Also FYI the biggest single improvement you can make is the exhaust system.

[02loftsmoor]

Thanks Mark, just looking for some tips to stay out of trouble,, never did a type 4 so i will ask for help.

[Dave_Darling]

Here's a tip: Don't touch the short radius of the exhaust port. Taking material off there doesn't help flow much if at all, and it takes material out of a part of the head that is a bit marginal in strength already.

--DD

[02loftsmoor]

Here's a tip: Don't touch the short radius of the exhaust port. Taking material off there doesn't help flow much if at all, and it takes material out of a part of the head that is a bit marginal in strength already.

--DD

--DD could up help out this knowledge challenged person right where in int port that is please.. Wes

[Al Meredith]

On the 1.7 heads I install a copper exhaust gasket and note the amount of meat arround the gasket. I'll bet I remove 10% of the opening to match the gasket. This only works on the 1.7 as there is plenty of excess alunimum in the exhaust stream,

[Dave_Darling]

The port bends, right? At the valve the port is pointing more or less outward, and it bends to point downward. Because of the curve, one side of the port has a tight turn radius, and the other has a larger radius. Don't take material away from the side of the port that has the tight turn radius.

That's the part that is facing down when the head is mounted on the car.

Here's a picture of a 1.7 head cut straight through the port:

(IMG:http://www.914world.com/bbs2/uploads_offsite/www.aircooledtech.com-121-1408750671.1.jpg)

It's from this thread on Shoptalk: http://www.shoptalkforums.com/viewtopic.php?t=71523

The short-radius bend is the very short and kind of sharp bend visible at the bottom (toward the bottom of the photo) of the valve seat.

--DD

[02loftsmoor]

clear now,,, Thank you that's what I'm talking about!

it looks like you can't take much out any where

[Jake Raby]

You'll need the flow bench to shops you that your first few sets of ported heads will flow less than stock.

And, of course its not just gross flow that counts, its mixture quality, so you'll need a pitot tube and a swirl meter, too.

And, then you always have to ensure the camshaft is optimized to the ports…

Then you'll have to play with port flow margins intake to exhaust.

Its fun. You'll love it. If you're lucky you'll get to do it everyday, but don't ever be dumb enough to start selling what you know.

[Dave_Darling]

Remember that those are smog-port heads, so the port has the extra room for the air injectors, and the bosses for the injectors to come through.

The thread I linked has some pretty decent discussion of porting the Type IV cylinder head, though it is rather dated now. I suspect that it may be enough to give you an idea of some of the basics, but the current state of the art is well beyond that now. (Stuff happens in a decade where dedicated people are trying hard to improve things--who'd'a thunk it? (IMG:style_emoticons/default/wink.gif) )

Oh, and you might see some familiar names on that thread.... (IMG:style_emoticons/default/biggrin.gif)

--DD

[ThePaintedMan]

At some point, every "car guy" learns to specialize in what they themselves know. Engines, transmission and installing glass are just a few things that I leave to the pros like Jake, Len, McMark, etc. Eventually you realize that the costs in tooling and time are not worth it - you'll never get it back. I will eventually rebuild a Type 4 for my own understanding, but I'll never get the HP out of it that those guys do. Sometimes it's better to just spend the $ and trust that you're not being (IMG:style_emoticons/default/sheeplove.gif). They're good peoples.

[colingreene]

Ive flow benched my stock 2.0 heads after seeing the data i opted not to touch them for reliability sake
Also add to the fact that they flow pretty damn well.
Plus you are building a 2056 right? Its not a huge jump in displacement
Id recommend you leave them alone.
a good valve job is going to do more for you than anything else.

[02loftsmoor]

guys thank you for the input, I think I'll leave it to the pros, I do have a set of 2.0 Porsche heads that need repaired, have said that I have the extra set of 1.7 heads to fiddle with,, flow bench your getting out of my league, I don't know what I'm looking for, and the expense for a one or two time job is not worth it,,

All and all you guys did give me a direction to move to, and I thank you..

Now what lift and duration cam do I need to buy for a 2056cc, 2.0 heads, 40 webbers.

looking for mid-range power

[colingreene]

give web cam a call and as a few questions would be where id start.

[Jake Raby]

Keep in mind that cam grinders know their product very well… But they are not head porters or engine builders… They are usually among the least effective people to recommend a cam, UNLESS they have data to work from, like actual port flow.

Debbie is no longer at Web Cam, that chick was the T4 specialist there, no one knew more about the T4 cams than she did, other than Steve, the Owner.

[02loftsmoor]

I will take the tips to heart thank you

[stugray]

A webcam 86b is not overly aggressive for the street and works well with carbs.

Their description of it: Strong mid and upper end performance for small displacement racing engines.

Will require setting of the valve geometry but nothing to worry about in the valve to piston clearance dept on stock parts and stock deck height.

[HAM Inc]

If I spend 10 minutes on a 1.7 ex port I will need to spend around 40 minutes on the intake port to keep a 75% ex/in flow ratio.

On a 2.0 914 10 minutes on the ex port requires about 20 minutes on the intake.

YMMV