OST-069: Transformation

[oldeskewltoy]

OST-069 begins its transformation with a cleaning.....

Nasty..... top





and bottom....




and while a cleaning gets it suitable for work....




it is still too nasty to sell... so add another step... tumble it!!








more to come....

[oldeskewltoy]

Maybe I have missed this, but you have a big tumble cleaner that are large enough to fit engine heads? :dumb:

No, one of the machine shops I use has a large "tumbler" - large enough for blocks! The tumbler is partially filled with zinc shot. They close the lid and the head is dragged repeatedly though the zinc shot.



Porting begins.... #1 on the right had a bit of a step left after the factory machining, I cut this back and smoothed it out. On the left, #2, adjusting the seat and bowl




I frequently have to "fix" core shift, here is a prime example from the exhaust side




2 down... 2 to go....





more to come......

[oldeskewltoy]

I have seen people smooth the valve guides down so they are flush with the IN/EX channel, is there any reason for doing this, or is it overdoing it.?

good question....

I assume you mean something similar to this.....




the actual 4AGE/ZE valve guide is all of 1.6" long....it holds the 4AG valve stable at valve speeds up to 75 opening/closings per second......



The more you shorten it, the less stable the valve becomes. Shorten it a little, and it isn't likely to be an issue, shorten it more....???

But how short is too short??


I can't tell you..... for I don't know.


What I do know, is Loynings does use guides on many of their 4AG race engines, while removing the guide boss, they still keep the guides....






In the same breath... I have shortened guides in one of my head builds... but it wasn't a 4AG... and it wasn't shortening them as much as in the above photo.

I was building a 1GG head, and the guides were longer then the 4AG guides, with similar, or less lift then a 4AG..... so I shortened them

intake....


exhaust....






When I port heads I've tried to follow one underlying rule..... "do no harm"

[oldeskewltoy]

So... this package cleared customs 3 days ago....... what could it be.......





A full Toda BSpec valve train kit*... along with a pair of Toda 272 10.3mm cams...

* The BSpec kit is completely different then the "common" Toda springs I typically use, this kit is capable of handling 11mm lift cams




Too clear big cams, a bit of extra work is required so they can actually turn in the casting




small clearance pads are cut so the cam won't hit the head





more to come....

[oldeskewltoy]

So the head has come back from getting its valve job....









then the client asks me if it is too late to add an intake side oil drain.....





now that the drain has been fitted, I move on to get chamber volumes - 37cc each across the 4




Client wants 36cc, so the head will get machined .008".



More to come.....

[oldeskewltoy]

SO another Newbie question :angel:

36cc vs 37cc, is there a sweat spot on a 4age, or is this just to get the correct combustion ratio?

What is the standard chamber volume, on a 16V Big port?

We are fine tuning final compression ratio. In this case 36cc along with his piston choice, and gasket choice deliver the final CR desired.

Standard 16V chamber is 36cc. In this case to get the chambers de-shrouded it required adding 1cc of volume.

What does the intake oil drain do? Prevent oil from getting clogged up in the head?

It helps keep oil down in the oil pan. The 4AG largeport head only drains on the exhaust side - fine for transverse layout, but in a longitudinal layout a long left hand sweeper can emply the oil pan of oil and pack it into the head. Additionally it helps with a catch can as often times the catch can fills for the same reason.