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....

[Mylesmck]

Nice work

Sent from my ANE-LX1 using Tapatalk

[banpei]

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

[oldeskewltoy]

(11-07-2020 10:34 PM)banpei Wrote:  Maybe I have missed this, but you have a big tumble cleaner that are large enough to fit engine heads?

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......

[banpei]

(11-12-2020 11:04 PM)oldeskewltoy Wrote:  

(11-07-2020 10:34 PM)banpei Wrote:  Maybe I have missed this, but you have a big tumble cleaner that are large enough to fit engine heads?

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.

Nice!
I was always wondering how you get those heads look like new but now we know your secret.

[Ivan141]

Vapour blasting makes for an even nicer looking result.. not too common though.
The tumbler probably gets to hard to reach inside cavities better, but that is as much of a risk as a benefit.

[Vaptor]

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.?

[oldeskewltoy]

(11-15-2020 11:07 PM)Vaptor Wrote:  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"

[Vaptor]

Thank you Dan for this deep explanation to my question

First picture was exactly what I was referring to.

With standard Guides length, it can keep the valve stable to a max of 75 opening/closing per sec, so for High RPM with High lift, better keep the Guides to a standard length and not experiment to much, although the Lorring approach looks interesting

[oldeskewltoy]

(11-25-2020 09:49 PM)Vaptor Wrote:  Thank you Dan for this deep explanation to my question

First picture was exactly what I was referring to.

With standard Guides length, it can keep the valve stable to a max of 75 opening/closing per sec, so for High RPM with High lift, better keep the Guides to a standard length and not experiment to much, although the Lorring approach looks interesting

be careful about using absolutes - some 4AG engines (Loynings, or Hasselgren) make then to spin upwards of 92 valve oscillation (openings/closings) per second