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Ever wonder just how thick your head is ??

head-holes.JPG

A generic picture from google images of 6.5 head. Are heads plugged between valves for each cylinder or just the end ones?

Isn't this the saw cut yellow line?

Can coolant pass upward in red hole see previous post to intersect the through drill or is that the air pocket you were talking about?
 
The plug like thing is in every head I have cut and in every cly.... it is for sure a factory thing, I would guess they did it to help strengthen the valve area, the air pocket is the other side of the plug schicker......

This head is cracked in 2 places, between the valves, last I will cut the head in a crack and see what it shows...
 
head-hole-2.JPG
1. The red square/X is air pocket?
2. Does the blue line represent what coolant might do dead head into the bore?

3. Does the drilled bore intersect other parts of the water jacket such that the volume of "stagnate" coolant is actually pretty small?
 
The blue area is an air gap (I think) unless I mistook my machinist explanation. That is the area under those little freeze plugs right?
 
Burning oil said:
The blue area is an air gap (I think) unless I mistook my machinist explanation. That is the area under those little freeze plugs right?
Click to expand...
That bore used to be a wide open coolant jacket ( at least it was with the head from a 95 that i cut up cause it did not have these plugs in it
Crack repair between the valves used to be done with drilling the bore up to accept a pressed in valve guide. It sealed the crack and still left adequate coolant flow.
It seems like the threaded plug is a factory attempt to prevent cracking,..it obviously did not work if it still cracks and by the looks of it all it did was impair coolant flow.
 
schiker said:
View attachment 44861
1. The red square/X is air pocket?
2. Does the blue line represent what coolant might do dead head into the bore?

3. Does the drilled bore intersect other parts of the water jacket such that the volume of "stagnate" coolant is actually pretty small?
Click to expand...

1. YES, on the motor the tilt will produce a air pocket....

2. Again, yes, coolant just sits in that passage, very little if any circulation there..

3. I haven't made a cut horizontally in that area to see.... nothing I could do about that if I did find it....

Keep in mind this all started when " I / me " needed to know the thickness in places in the runners, not just a "swag" ..... and the rest is just to ponder over.... very easy to see how STEAM POCKETS really is something to be concerned about in a 6.5.... makes me glad I like Evans....
 
One last thing to ponder ... might need to fill the coolant system on the motor stand and roll it around just to get the air out.... LOL, just kidding here..
 
With the turbulent flow the air pocket probably gets flushed to a minimum. I have seen bubbles stay in a loop of clear hose. Bubbles won't flow downhill with laminar flow (even really strong flow). But maybe with strong turbulent it might flush.

" Interesting in that the blue area there are no signs of boiling or cavitation." Doesn't mean it won't boil when high ECT especially if dead headed???.

The surface finish is pretty smooth which is more corrosion/erosion resistant. Notice less rust verses the water jacket, threads, etc.
 
This head has been tanked a LOT... and spent some time in the acid also so it being very clean doesn't count for much, can't tell how the water passages were before the cleaning...
 
OK so the obvious question for me is. Would it be beneficial if water could pass though that area? It would be pretty easy to tap the head for some barbed fittings and make a manifold system that returned that coolant to the radiator.

By the way I have AMG working on getting "us" a head to cut up. Chris do you want to do the honors of cutting it up? (if I actually can get one)
 
Seems also an easy fix would be drill a smaller hole through the plug to open flow through plug but leave some meat to plug if it's to strengthen cast.

airpocket-plug.JPG
This is the air pocket (if head is mounted it can trap air in a bubble up this bore) right?

Hard to see if its at an angle or if plug centerline is on centerline with drill thru. Might just restrict flow.

Can you see light through the manifold threaded hole side?
 
Burning oil said:
By the way I have AMG working on getting "us" a head to cut up.
Click to expand...

Seeing as AMG is going to let us cut it open, it looks like they are not concerned about trade secrets. Any possibility of getting a set of CAD drawings? Or are they looking for "us" to give "them" information about what the inside of their head looks like????
 
Plenty of meat on the short side radius, but it sure gets thin at the transition of the seat to the bowl! :eek:
 
Nice cut pics of the runners up to the valve bowl. Regarding installing hardened valve seats in the GM 6.5 heads, it's not uncommon. Years back, I had a local Kansas City cyl head shop (Noland Cylinder Heads) rework my stock heads. They'd done lot of work for a local fleet of the Frito-Lay vans with 6.5's. That experience led them to installing hardened valve seats as well as pro-actively drilling that coolant passage & pressing in a valve guide liner - as a standard practice on the GM 6.5 heads to eliminate comeback problems.

Will be interesting to see how the AMG head compares. If they didn't get into the coolant passages machining for valve seat inserts, the inserts & the coolant passage fix are typically longterm reliable, but expect AMG's improved design is cost effective & even more reliable.
 
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