OST-056: Nasty.....

[oldeskewltoy]

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





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




more to come......

[oldeskewltoy]

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

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





also working the exhaust side




more to come......

[oldeskewltoy]

oldeskewltoy Wrote:

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




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




more to come.......

[Project D]

(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

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

[Dave W]

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

[oldeskewltoy]

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."







^ 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....


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



more to come....

[Bean]

(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

Sent from my MHA-L29 using Tapatalk

[oldeskewltoy]

(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

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....





next, checking chamber volumes...







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



more to come....

[Bean]

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.

Sent from my MHA-L29 using Tapatalk

[oldeskewltoy]

(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.

Sent from my MHA-L29 using Tapatalk

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




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


more to come....