Today's project at work: John Deere "small block" getting big valves. With some nasty core shift to boot. Somehow didn't break into water...and If I did we'd just fill it full of concrete anyway.
Today's project at work: John Deere "small block" getting big valves. With some nasty core shift to boot. Somehow didn't break into water...and If I did we'd just fill it full of concrete anyway.
So this summer was a bit slow........ and a bit sad too.
Loynings Engine Service has closed for good. Arnie is getting up there, now over 80. Some views of an empty shop.........
Oh... and another 4AG head.... 
working the exhaust side
more to come.........
20V Silvertop
long time, no update....
Sometimes part of the job is fitting a manifold. This dual DCOE manifold for Toyota's 3TC engine could have been made better.
As you see, the edge of the port is actually beyond the gasket on these 2 ports.....
So I had no other choice - weld it, and reshape it
New seats for a big valve head
I feel this little guys looking at me.
oldeskewltoy said:20V Silvertop
How much do these flow compared to the 16V heads? To my barely trained eyes, a lot of the curtain area is shrouded by the cylinder walls and the adjacent valves.
It does do a nice job of shading the combustion chamber to the exhaust side of the head, at least, so more of the unburned gases are towards the intake side for another chance to be lit off. If you're going to have residuals, may as well be burnable ones instead of waste gases.
Pete. (l33t FS) said:oldeskewltoy said:20V Silvertop
How much do these flow compared to the 16V heads? To my barely trained eyes, a lot of the curtain area is shrouded by the cylinder walls and the adjacent valves.
interestingly... low lifts there is significantly more flow, as lifts rise the advantage becomes less. A big valve 16V head flows considerably more.
oldeskewltoy said:New seats for a big valve head
Big valve head removes so many original flaws....
Bowls 7(on right) and 8 in chamber 4 as bowl 7 transitions between standard, and big valve.
Not Toyota, not import, not even aluminum - working another oddball, a early/mid 90s 4.0 liter Jeep head.. client does not have a lot of money, but wanted some improvement with his Jeep Cherokee.
After going through and checking, I found 1) some very poor bowl/seat alignment, 2) intake throats at 86%, while exhaust throats were a rather small 78%. Additionally the roof of the exhaust port bends down at the base of the guide boss, and is .050" lower at port exit . Oh, 2 of the 6 port outlets are "D" shaped, that is why the somewhat odd looking exhaust ports
more to come...... 
I've done a couple of 4.0 before. Nothing about them is "ideal" but pretty big gains can be made.
Building a car for endurance racing, have to switch headers back to stock manifolds to get within my class competitive points.
Port the stock manifolds prior to putting them on?
Car is a 2006 Mustang 4.6L V8. Cast iron log manifold.
All advice is greatly appreciated.
kevinatfms said:Building a car for endurance racing, have to switch headers back to stock manifolds to get within my class competitive points.
Port the stock manifolds prior to putting them on?
Car is a 2006 Mustang 4.6L V8. Cast iron log manifold.
All advice is greatly appreciated.
If budget allows... Extrude Hone will remove casting imperfections, and open the passages some.
Now working the intake side, aligning the bowl and port, rebuilding the short radius, and shrinking the guide boss
doing some reading.........
In reply to oldeskewltoy :
They are stripping and cleaning the head early next week. You should see it soon
In reply to Trent :
I'm excited to see how this project comes together! 😁
in the mean time........
smallport 4AG - fixing the short radius....
Here is the clean Alfa twin spark head. A few pointers - First, you can see the "crowding" on all of the exhaust ports, especially from 9 to 12, and from 12 to 3 o'clock position - its worse inside the bowls. Second, take note of the intake flange (its water cooled) the cut away from the book doesn't seem to show
The book diagram, AND head cut away
More to come.....
awesome
Some new equipment required....
The new sanding rolls are the 1/2" on the left.
Running bigger valves require larger seats. After the old seats are pulled....
now fitted with larger seats. Can you see the edges of the significant flaws in intake bowls 2 and 4??
more to come...
So port work begins... 1 on the right.....
Same 2 ports/bowls, different angle
As I mentioned above..., "can see the "crowding" on all of the exhaust ports, especially from 9 to 12, and from 12 to 3 o'clock position - its worse inside the bowls." Lets take a quick look
The bowl casting gets very tight right where you need the most room, getting past the guide and valve stem. The bottom view in the above 2 panel only shows the improvement by removing the obstruction, the bowl, and seat get larger as porting on this exhaust port proceeds.
One down....
more to come...
And here is another example of the crowding on the exhaust side
So, a bit of discovery..... While I've encountered port/bowl flaws in the past, none quite reach this level. Bowls 1 and 3 while poorly aligned aren't anywhere near as misaligned as port/bowls 2 and 4.
This is how bad the alignment actually is
Intake bowl 4 before, and after
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