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oldeskewltoy

Ost-032: Skippy Gets A Head

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I've recently purchased a daily-able FX16 so I don't have to use Surreptitious(AE71) all the time...

 

Craigslist_photo_9.jpg

 

I named the FX "Skippy", and knew upon purchase that it didn't run.

 

 

 

This is what was found when the head was pulled... something broke, and eventually got embedded - see arrow

 

normal_chamber__3_s_damage_annoted.jpg

 

So.... OST-032 is Skippy's new head!

 

ost-032.jpg

 

 

 

stripped and ready for cleaning........

 

chamber_view.jpg

 

 

 

Can anyone tell me why one chamber is already clean????

 

 

 

More to come..... :D

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Can anyone tell me why one chamber is already clean????

 

 

 

More to come..... :D

 

 

 

blown head gasket' date=' water jacket breach = steam clean. (?)[/quote']

 

normally this would be a great guess....

 

Ignition failure in number one.

Un-burnt fuel soaked the chamber and over time it cleaned all the carbon off' date=' I saw this once in a 4AFE head.

[/quote']

 

as is this.....

 

But in reality this was a VERY loaded question - apologies. This chamber was the chamber used to make the chamber casting....

 

 

stockchambercasting_zps3882af7d.jpg

 

casting-stockchamber_zpsd27847e9.jpg

 

 

 

more to come...... :D

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So Skippy's head is back from cleaning and pressure checking. The chamber depths and the seat depth all look VERY good. There is some excess material that was left behind after the head was machined @ Toyota, that will all get cleaned up :thumbsup:

 

chamber_view__4_begun.jpg

 

 

It measures just about what an uncut head is suppose to measure - easily within the .001" tolerance of this caliper

 

normal_stock_thickness.jpg

 

 

Work begins on chamber/bowls of #4 cylinder

 

work_begun_on__4_intake_bowls_get_their_shape.jpg

 

 

 

More to come.... :D

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I'm going to ask a potentially stupid questiom. Why do you need the chamber casting?

Edited by ke70dave

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I'm going to ask a potentially stupid questiom. Why do you need the chamber casting?

 

no question is stupid... on the other hand some answers.......????? :yak:

 

 

The chamber casting was teaching myself a lesson on how to do it!

 

casting-beginning_zps8a8f6c3a.jpg

 

 

 

After I made the casting I sent it, along with a bunch of pistons to JE Piston to design a "new" piston for the 4AGE.

 

28kufwj.jpg

 

 

I also use it to demonstrate the positive space view of my chamber work....

 

casting-chambercomparison1_zps91cb885f.jpg

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Work begins

 

 

and continues....... :)

 

@ cylinder #4....

 

 

deshrouding....

 

chamber_deshrouding_2_panel.jpg

 

 

 

...and working the exhaust....

 

exhaust_ports__just_2_2_panel.jpg

 

 

 

2 cylinders down' date='

 

[img']http://ost.ebeans.ch/albums/userpics/10005/normal_chamber_view_2_down.jpg[/img]

 

 

 

2 to go.... more to come.... :D

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After I made the casting I sent it, along with a bunch of pistons to JE Piston to design a "new" piston for the 4AGE.

 

So they could forge a set of correctly sized pistons with over-sized unfinished crowns for you to finish as you wished?

 

These are great threads, I'm sure a lot of guys just starting on motors are realising how straight-forward head work is and what can be done. A 4K benefits from the same work, a motor is a motor until you're down to the last few percent of extra bhp.

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As I am sure you are aware, the TRD Group A manual says to polish the joggles (the areas around the deshrouding) until they yield smooth reflective surfaces, and not to polish the other portions (the areas not bounded by the deshroud).

 

Looks like you have polished the whole chamber?

 

Any thoughts on TRD's thinking there?

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So they could forge a set of correctly sized pistons with over-sized unfinished crowns for you to finish as you wished?

 

They use them to digitize the model to cut the forging, makes it easier to program the cnc.

To do it like your saying "as forged crown" would be a min order of 500+ parts and an outlay of thousands of dollars in die work. It is a nice way to do it but not really economically viable.

 

 

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As I am sure you are aware, the TRD Group A manual says to polish the joggles (the areas around the deshrouding) until they yield smooth reflective surfaces, and not to polish the other portions (the areas not bounded by the deshroud).

 

Looks like you have polished the whole chamber?

 

Any thoughts on TRD's thinking there?

 

Not the WHOLE chamber... but I have extended my work a bit beyond the original TRD joggles. Because of my experience with these heads I've found that the spark plug hole needs a bit of radius-ing, in addition the peak of the chamber will often times see a bit of work as well, BUT the areas between the paired valves is left as it was cast.....

 

As to the why? It all has to do with how the head handles heat. The more heat you can remove, the higher the operational compression can be. By removing all the sharp edges we can raise the detonation resistance substantially

 

 

From an earlier job....

 

flg3z5.jpg

 

 

So they could forge a set of correctly sized pistons with over-sized unfinished crowns for you to finish as you wished?

 

 

actually.... so JE Piston FINALLY had accurate information as to what a "stock" 4AG was about. ALL the stocking 4AG pistons on the market are based on very suspect information (39CC chamber for one example). My purpose in sending the castings on was to get accurate information into the market.

 

As to the piston above... look very carefully.....

 

it is basically a TRD Group A piston crown...... but JE and I included full skirts......

 

crownofMahleforOST-JEPiston_zpsa576ebe2.jpg

 

As to how it all fits together...... many builders seem to forget the piston crown is nearly 50% of the combustion chamber... a good crown can raise compression and improve flame propagation all at the same time.... below shows a chamber over a 10.3 high comp piston, and over the TRD type crown - note the height of the crown isn't significantly different, while the compression change goes from 10.3 to 10.7 with just the piston change....

 

chamberover103andTRD2panel_zpsc0e11164.jpg

 

 

Add in a tighter head gasket for improved "squish" and a machined, DESHROUDED head and your compression jumps over 11 to 1, all inside a very effect chamber for dealing with heat.....

Edited by oldeskewltoy

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It's far easier to take the direct path......then the path with the bend einstein3.gif

 

 

 

 

bends are gone......

 

2_of_2_exhaust_3_panel_gif.gif

 

 

more to come.... :D

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chamber_view.gif

 

Now that the casting has been massaged... It'll go off to the shop on Monday to get its 3 angle, and have the head surfaced.

 

More to come.... :D

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So... Skippy's head is back and it carries a fresh 3 angle valve job, and a minimal machining - .004".

 

I only had the head cut .004" so I could keep some of the deshrouding volume - target chamber volume of 36.5cc. I did this so I could keep the static compression high, but manageable @ about 10.7 to 1, and tighten the squish gap by about 20%

 

Specs 3.209" bore, 3.0315" stroke, .036 gasket, deck is .001 (under), piston volume 2/10 of a cc crown, with a 36.5cc chamber.

 

preparing to check chamber volume.... note the wooden shims under the head to get it at a slight angle

 

 

checking_chamber_volume2.jpg

 

 

measuring chamber #1....

 

checking_chamber_volume.jpg

 

 

and the result......??????? Bullseye 36.5cc!!

 

chamber_volume_36_5.jpg

 

 

 

The chambers are now perfect, Skippy's head is now ready for reassembly....

 

chamber_volumes_set.jpg

 

 

"Perfect"? It appears that chamber #4 is tight, or so it seems in the photo. It WAS a bit tight, I worked the chamber walls a little adding a 1/10 of a cc to the chamber.

 

 

This was a partial head when I began, the valves in this head were not originals to this head, so in this case although being re-assembled, I fully expect SOME dis-assembly of the valves for those needing to be tipped.

 

 

More to come.... :D

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I knew there was a reason why you wrap the head in bubble wrap, take it to the machinist, come back a couple of weeks later, hand over lots of money and put said head back on engine......

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