(Catching up...) OST-085: 7AG Big Valve build w/Cat Cams 262 9.0mm lift cams
07-28-2022, 01:18 AM
Post: #1
(Catching up...) OST-085: 7AG Big Valve build w/Cat Cams 262 9.0mm lift cams
Boy that title was a mouthful... As is with other "catching up" threads, I'll be posting the entire build in the first post.


[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]



This is what arrives....

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]


The head goes through the usual routine - cleaning, and pressure checking the casting, but before any porting takes place all the valve seats are removed....

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]

... and in this case the head waits.... and waits..... and waits.

After nearly a month I ask Mike what's the delay - their source for the big valve valve seats hasn't got any!

Good thing I use two different shops - I ask Ted, and he gets the new seats in 5 days!

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]



After nearly 6 weeks, the head is back in my hands, and the new Cat cams have arrived. First job fit the new cams to the bare head - make sure the spin freely

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]



The chamber side prior to porting - note the added intake side oil drain - another request from my client

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]


Porting finally begins.... cylinder #1

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]


Cyl #1 on the right.... keep your eye on the flaw, and cavity in #4 bowl (far left)

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]


Here is a before and after showing the short side of the intake bowls of #1 and #2 cylinders

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]


As you can plainly see ALL of the casting flaws just disappear....... but do they??? The 2nd gen largeport, and the smallport are common to have poorly aligned/cast heads.


How bad you say... here is an intake bowl still showing the original casting even after moving the bowl wall nearly 3/4 of a milimeter (.030")

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]

It isn't a huge flaw - now, but with a standard valve in there the flaw would have been power robbing!



With the bigger exhaust valves and bowls... a larger exit is required....

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]

....from roughly 29mm-30mm, out to 34mm. Gasket can handle 35mm outlet.


With Porting complete, the head goes back to Loynings where they put the head in their Rottler seat and guide machine to cut a fresh 3 angle into those new seats.

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]



And just prior to final assembly

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]

Dan -

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

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
Find all posts by this user
08-21-2022, 09:44 PM
Post: #2
(Catching up...) OST-085: 7AG Big Valve build w/Cat Cams 262 9.0mm lift cams
Another Great Head Smile

Do you have any pointers on how best to be add a intake side oil drain, on a Big Port?

Restoring my AE86, all the way... Going JDM style Big Grin
http://www.aeu86.org/viewtopic/ae86/p/150463#150463
Find all posts by this user
08-22-2022, 09:15 AM
Post: #3
(Catching up...) OST-085: 7AG Big Valve build w/Cat Cams 262 9.0mm lift cams
Beautiful work as always! Thumbs up!
What would you suggest if the flaw would have been bigger? Get another head and hope there isn't a flaw or the flaw is smaller?

1982 - TA60 Carina 4dr sedan - fun cruiser
1983 - AE86 Sprinter Trueno - import project
2013 - Honda Civic sport - daily driver
2004 - AEU86 dot ORG - daily domain

Support our forum, buy from the AEU86 shop:
[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]
Visit this user's website Find all posts by this user
08-22-2022, 09:59 AM
Post: #4
(Catching up...) OST-085: 7AG Big Valve build w/Cat Cams 262 9.0mm lift cams
I would expect a TIG torch is able to reach in there.. you could just fill it up with weld.
Anyway.. nice work, I'm also interested in some pointers on the extra oil drain.

FABRICA MI DIEM, PVNC!
Visit this user's website Find all posts by this user
08-31-2022, 09:38 PM
Post: #5
(Catching up...) OST-085: 7AG Big Valve build w/Cat Cams 262 9.0mm lift cams
working the oil drain is no small feat.... even when installed correctly, they can be fragile.

Adding it starts with courage (about to drill and could possibly ruin the head), and a wide selection of drill bits, along with burrs to get the hole open in the right place. Then the tap is used to further open the hole and add threads.

This was a gif from about 7 years back....

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]

The problem with this one (above) is it can interfere with coolant plumbing at the back of the head. As my work later progresses, I move the fitting for better fitment.

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]

Using essentially the same tools (various drill bits, and burrs) to properly open the hole to accept the 3/8" NPT tap.


briefly speaking to its fragility.... and placement

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]


I offer 3 types of fittings....

[Image: AEU86 AE86 - (Catching up...)  OST-085: ... lift cams]

Dan -

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

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
Find all posts by this user
09-09-2022, 09:07 PM
Post: #6
(Catching up...) OST-085: 7AG Big Valve build w/Cat Cams 262 9.0mm lift cams
Thank you for this great post, now I have some pointers to show the machine shop, when I get to this stage (Will get it done before Headwork, just to be sure).

Restoring my AE86, all the way... Going JDM style Big Grin
http://www.aeu86.org/viewtopic/ae86/p/150463#150463
Find all posts by this user


Possibly Related Threads...
Thread Author Replies Views Last Post
  OST-093: My, My, Mystery oldeskewltoy 10 749 09-18-2022 02:19 AM
Last Post: oldeskewltoy
  (Catching up...) OST-083: Salvage operation oldeskewltoy 2 353 07-11-2022 08:32 PM
Last Post: banpei
  (Catching up...) OST-082: Nope, never again... at least not without all the parts oldeskewltoy 0 307 06-28-2022 09:17 PM
Last Post: oldeskewltoy
  (Catching up...) OST-081: STOP... do not touch if you don't know wtf you are doing oldeskewltoy 0 391 06-17-2022 09:07 PM
Last Post: oldeskewltoy
  (Catching up) OST-080 (and OST-074):Dan Dabbles in Dubs oldeskewltoy 0 334 06-13-2022 05:33 PM
Last Post: oldeskewltoy

Forum Jump:


User(s) browsing this thread: 1 Guest(s)

Contact Us | AEU86 | Return to Top | Return to Content | Lite (Archive) Mode | RSS Syndication