OST-013: Massaging a virgin ;)

[oldeskewltoy]

Well.... getting back to work.

Below is the finished combustion chambers.



Note there are no more machining "brows" around the bowls. All of the machining marks have been gently "massaged" away Also note the chamber edges (especially 2 and 3) have been gone over to remove the rough flash left behind by the factory machining process, no roughness, less chance of pre-ignition/ping.

I did make a mistake on the initial bowl measurements, chamber #4 (36.5cc) was measured incorrectly. I know this because of the final chamber volumes I got - 36.75cc. There is just no way the work chamber 4 received, netted to only .25cc. I checked, and double checked the chambers this time and now they are all @ 36.75cc


To better see the chamber work, I've done a before and after 2 panel on #4 chamber



It is far easier to see the chamber work in this 2 panel photo.

Besides the chamber work, you can now see the 2 intake bowls are now more or less complete. There is no mismatched seats, and casting debris is all gone, the guide bosses have been narrowed and the guides have received a taper in the direction of the flow.

[NoHachi]

Cool stuff.

For us dumbasses out there: what is a mismatched valve seat?

[Bean]

great work Dan - looking forward to put it to use.

@NoHachi: if you look at a stock 4age head (and loads of other heads too) you'll find that the casting from the ports doesn't line up with the valve seats, resulting in a sharp lip/step between the two which is very pour considering good flow.

to illustrate it from above picture (this is the #2 combustion chamber pre work)

if you look at the lower two ports (intake) you can see a shadow on the top portion of both ports below the valve seat where as explained the seat and port don't line up as they should, creating a lip.

[Project D]

the best way to see it:

[oldeskewltoy]

from the proverbial other forum Wrote:you ever think about knocking the valve guild all the way down?

oldeskewltoy Wrote:....their engines retain the guides. Theirs are more tapered then mine are,

Most of Loynings guides are tapered like a bullet, I do not have that machining capability, but I do have the capability to narrow/taper the guide concerning the direction of flow......


All the casting imperfections on the intake bowls has now been blended away........ only final details are left

You've seen #4 in an above post, here are 1-3

#1 before -



#1 after -




#2 before -



#2 after -




#3 before -



#3 after -



With the intake bowls all but finished, low and behold....


The new Supertech valves come

[Project D]

Smallport head + supertech will become a standard
I do the same thing except that I change Everything (from followers to valves including the valve guides) for Supertech product

[Bean]

Project D Wrote:Smallport head + supertech will become a standard
I do the same thing except that I change Everything (from followers to valves including the valve guides) for Supertech product

As the head is new I've seen no point in exchanging the valve guides (although I'm aware that the bronze ones have better heat transfer capabilities). Springs and Ti-retainers I have from Supertech too, along with guide seals. Followers I'll be using from the 1SZ-FE.

[oldeskewltoy]

As far as I know.... the OEM guides are bronze... in fact you can see them for yourself!

There are 2 reasons to change guides in an "A" head... wear, or changing valves to a narrower stem. In ALL the heads I've done to this point I've had to change 2 guides.... only 2. The 4AG head has quite a remarkable bit of engineering in it, largeport and smallport


A very useful 2 panel, there is a lot of information in that view. On top is the untouched port, below is the same port after getting it to the new size.



The red lines indicate 2 things:
1) they show the flash along the port walls (horizontal lines) which has now been removed and blended,

2) they also show, along with the veritical line running parallel with the valve guides, the area of the intake port that get major attention.

Note in the lower view, the outer channels along the outer edge of the guide bosses, are fully visible. In the top view these channels are NOT visible, and the arrows are pointing at these areas. The port top/roof has been "opened" up to allow the airflow an easier path past this restriction. Finally, the port floors (top of view) has remained untouched, retaining the larger radius it had before


Also note the valve seats have been blended into the bowl walls, all the flash has been blended, and the machining mark in the right hand port near the valve seat has been blended away.

[Project D]

I will change mine because they are rusted as hell !!
Original valve guides for 4A 16v engines are in cast iron
Manganese Bronze / Phosphor Bronze are yellowish and don't rust.

Many compagny offer bronze guides for 4AG:
Supertech, Toda, Jun, Naprec, Tec Art's, TRD (not available anymore) etc etc...

Just for showing, the "old" TRD valve guides:

(not tapered)

supertech:


Naprec:

[oldeskewltoy]

Concerning the guides...... I've learned something new.... I've only ever had to replace 2 guides... and I didn't replace them my machinist did.. I did a simple magnetic test and indeed the oem guides are iron/steel


Time to work the exhaust side....



2 down... 2 to go....

Any guesses as to which are which