OST-056: Nasty.....
05-01-2019, 07:01 PM
Post: #1
OST-056: Nasty.....
[Image: AEU86 AE86 - OST-056: Nasty.....]


Another first gen 4AG head, this one is a bit Nasty....

[Image: AEU86 AE86 - OST-056: Nasty.....]


Btw, here is a photo showing the difference between a 1st gen TVIS head, and a 2nd gen TVIS head. A first gen is what came on the AE86, the 2nd gen is later

[Image: AEU86 AE86 - OST-056: Nasty.....]



So, getting back to OST-056, the head is stripped, cleaned(?), and pressure checked. Once back, I deburr the casting

[Image: AEU86 AE86 - OST-056: Nasty.....]


more to come...... Hurray!

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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05-06-2019, 07:12 PM
Post: #2
OST-056: Nasty.....
from another forum Wrote:
oldeskewltoy Wrote:Btw, here is a photo showing the difference between a 1st gen TVIS head, and a 2nd gen TVIS head. A first gen is what came on the AE86, the 2nd gen is later

[Image: AEU86 AE86 - OST-056: Nasty.....]

I have to wonder if Toyota had the MR / FWD mounting in mind when they (or Yamaha) designed the 4A-GE. I have one each of the big port heads and noticed this difference.

I've yet to see a Toyota application that uses that mount...........






Work on the head proceeds.....



"Building" the intake side - blending the seat, bowl, and port Wink

[Image: AEU86 AE86 - OST-056: Nasty.....]



also working the exhaust side

[Image: AEU86 AE86 - OST-056: Nasty.....]


more to come...... Hurray!

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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05-10-2019, 09:05 PM
Post: #3
OST-056: Nasty.....
oldeskewltoy Wrote:[Image: AEU86 AE86 - OST-056: Nasty.....]

A facebook "viewer" asked if my work fits the stock gasket... I assured him it does......

[Image: AEU86 AE86 - OST-056: Nasty.....]


Further progress... 3 down... 1 to go

[Image: AEU86 AE86 - OST-056: Nasty.....]


more to come....... Hurray!

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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05-11-2019, 05:16 PM
Post: #4
OST-056: Nasty.....
(05-06-2019 07:12 PM)oldeskewltoy Wrote:  
from another forum Wrote:
oldeskewltoy Wrote:Btw, here is a photo showing the difference between a 1st gen TVIS head, and a 2nd gen TVIS head. A first gen is what came on the AE86, the 2nd gen is later

[Image: AEU86 AE86 - OST-056: Nasty.....]

I have to wonder if Toyota had the MR / FWD mounting in mind when they (or Yamaha) designed the 4A-GE. I have one each of the big port heads and noticed this difference.

I've yet to see a Toyota application that uses that mount...........

AE92
[Image: AEU86 AE86 - OST-056: Nasty.....]
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05-12-2019, 01:47 PM
Post: #5
OST-056: Nasty.....
Dan
I believe best practice is to match the top of the exhaust port with the header gasket [highest flow area] and leave the step mis-match at the bottom of the port for anti-reversion?
Dave W
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05-14-2019, 02:00 AM
Post: #6
OST-056: Nasty.....
Project D -

from another forum Wrote:I'm sorry I derailed the topic with this, but I guess we all learn something new every day. And I always love to see your work!

OK, here are some better pics. I had pulled all of the timing covers for my (someday, someday, someday) engine build, along with that small "cam bracket."

[Image: AEU86 AE86 - OST-056: Nasty.....]

[Image: AEU86 AE86 - OST-056: Nasty.....]

[Image: AEU86 AE86 - OST-056: Nasty.....]

^ Bracket looks smooth in parts because I've been taking off the casting lines & imperfections, so that I can get it powder coated along with other parts.
oldeskewltoy Wrote:After learning about AE92 the timing cover......


good lesson(for everyone)... even if you think you know it all....... you don't





(05-12-2019 01:47 PM)Dave W Wrote:  Dan
I believe best practice is to match the top of the exhaust port with the header gasket [highest flow area] and leave the step mis-match at the bottom of the port for anti-reversion?
Dave W

There isn't much to work with... most of my improvements take place inside... but on some heads..... that is why I worked with SV2 to help design the copper exhaust gasket - http://www.sv3power.com/store/index.php?...cts_id=217

Not only is it bigger, but part of the design was moving the bolts holes down (or exhaust ports up) by .020"

How it looks/fits....
[Image: AEU86 AE86 - OST-056: Nasty.....]

But this head isn't going to see that much exhaust port work....



more to come.... Hurray!

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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05-14-2019, 10:53 PM
Post: #7
OST-056: Nasty.....
(05-12-2019 01:47 PM)Dave W Wrote:  Dan
I believe best practice is to match the top of the exhaust port with the header gasket [highest flow area] and leave the step mis-match at the bottom of the port for anti-reversion?
Dave W
The pictures are taken with the head upside down Wink

Sent from my MHA-L29 using Tapatalk

AE86 ex-daily
[Image: AEU86 AE86 - OST-056: Nasty.....]
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05-17-2019, 12:15 AM
Post: #8
OST-056: Nasty.....
(05-14-2019 10:53 PM)Bean Wrote:  
(05-12-2019 01:47 PM)Dave W Wrote:  Dan
I believe best practice is to match the top of the exhaust port with the header gasket [highest flow area] and leave the step mis-match at the bottom of the port for anti-reversion?
Dave W
The pictures are taken with the head upside down Wink

Sent from my MHA-L29 using Tapatalk

ahh, I'm sorry I thought the ports being upside down was obvious... my apologies....



back from the machine shop wearing a new 3 angle, and back cut intake valves....

[Image: AEU86 AE86 - OST-056: Nasty.....]



next, checking chamber volumes...

[Image: AEU86 AE86 - OST-056: Nasty.....]





So if I want chambers down to 36cc, how much should I have machined from the head???



more to come.... Hurray!

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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05-17-2019, 12:47 AM
Post: #9
OST-056: Nasty.....
It's very late so my math might be off but I think about 1.5 thou (inches) sounds wrong but that's all I can come up with right now. I'm rusty with my numbers and a bit tipsy.

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AE86 ex-daily
[Image: AEU86 AE86 - OST-056: Nasty.....]
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05-17-2019, 05:52 PM
Post: #10
OST-056: Nasty.....
(05-17-2019 12:47 AM)Bean Wrote:  It's very late so my math might be off but I think about 1.5 thou (inches) sounds wrong but that's all I can come up with right now. I'm rusty with my numbers and a bit tipsy.

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well, about .008" is about 1cc(+ or -), so @ .6cc over, that would be about .005"

[Image: AEU86 AE86 - OST-056: Nasty.....]


and that's how much I had it machined.....


more to come.... Hurray!

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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