4age bigport head: port & polish

[cj]

I'm about to start a rebuild of my engine theses days. It's an early 4age bluetop (bigport). I'm planning an NA setup with the following upgrades:

Multilayer Steel Headgasket: Cometic
9 mm rod bolt kit: ARP
Crower Stage 3 camshafts
Toda Racing valve springs
T3 Adjustable cam gears
4-1 header (bg custom made)
Adjustable fuel pressure regulator
295cc injectors
Intake Adapter (custom made)
Individual Throttle Bodies (Delorto carbs)
Megasquirt unit
Underbucket shims (to be ordered after inspection)
Raplacement of whatever is needed after inspection of engine parts

a link to my project: http://www.aeu86.org/viewtopic.php?t=3632&highlight=

My question is whether to port or/and polish the head and should i do it only on the exhaust part? Does anyone have a "how to" or "step by step" tutorial?

[cannabolic]

as far as I know you don't polish the intake ports. It's because if u do the air doesn't get turbulense which results in a poor gasoline/air mix.
just give it a better breathing by getting off the big bits.

apardal has done it, ask him(look in his project)

cheers

[NoHachi]

Polishing the exhaust is ok...though you wont see much results for your effort. For the rest just grind away any casting remains that you see in the air stream and match the ports to the intake

[adomz]

yup. bleprinting is a really good thing to do!

and there was something more that i wanted to write...but i can't remember...damn disturbers... LoL...

adam

[BenR]

A good 4age head reqiures ALOT of work to completely reshape the ports, account for casting shift, reconfiguration of the valve seats geometry, valve modification etc.

So a guide would take longer to write than to do the head. Not that i would write a guide on how to do the ultimate 4age head as its what i do for a living lol.

[alimonos]

BenR Wrote:Not that i would write a guide on how to do the ultimate 4age head as its what i do for a living lol.

I wouldn't agree with you more Ben BUT what do you have to lose from guys like me who will never be your clients ???
Why don't you help US ???
Thanks

[BenR]

because if i post it on the internet then anybody, not just you, can do it and i loose my competitive edge.

Its more than likely you wont have the tools anyway so just concentrate on the bowl area and short side, thats all you will need to do.
Dont bother tarting it up.

[NoHachi]

Ben I think the most anyone here could ever hope to achieve is a mild cleanup job and perhaps matching some stuff here and there. The true racing portjobs will remain safe in your hands. However if you have a few pointers for us diy'ers to do some of the simplest jobs it would be welcome.

[jamiemirror]

BenR Wrote:A good 4age head reqiures ALOT of work to completely reshape the ports, account for casting shift, reconfiguration of the valve seats geometry, valve modification etc.

So a guide would take longer to write than to do the head. Not that i would write a guide on how to do the ultimate 4age head as its what i do for a living lol.

CJ wants good NA head, not ultimate one. As I understand the goal - this must be 150-170hp street engine, not 190-220 hp racing circuit screamer.
Regrinding valve seats and valves, 3-angle job, castings cleaning and porting is not ALOT of work (compared to FIAT 8V DOHC head for example - with more than 3mm wall material removed just to match ports to intake). Toyota have good and precise castings.

The question is what are general DOs and DON'Ts for bigport 4AGE head.

[BenR]

Yes i know, but the majority of the basic work is quite easy and clear for all to see.

Just get a stock head and you can see the problems.

Leave the stock seats unless you can find someone who actually knows what to do regarding cutting valve seats properly. I've just spent £50,000 on a cnc valve seat machine for this very purpose.

In the pics you can see the stock head, and how you clean up the bowls, this is the only area you need to concentrate on, forget about the whole port, just the bowls.

Tidy it up with carbide burrs, then just smooth it with some 80 grit 1" wide emry clotch on a slotted shaft, be careful of the seats at all times.

You can also see what is needed to be done on the short sides and how far from 'round' they are and how they do not point in the same direction due to the ports offset.