1974 bus cylinder head and piston condition

[whc03grady]

I hope not to have to buy new heads. Mine are AMCs with ~13,000 miles on them. When Ludwig's crank broke, there was (obviously) some greater travel allowed by #1 (left), as these photos attest. The piston appears to have thwacked the head a few times.




The local machine shop guy says it clearly just happened after the crank broke--it being all bright and shiny and all. He also said, looking at the head, "I don't see any high spots, so I don't think it needs machined."
I'm suspicious--do I believe him? And what about that piston?

Second question: Since the heads are out anyway, how about installing sodium-filled valves? Worth it/not worth it?

[chitwnvw]

My 2 cents. Check for recessed valves, doesn't look lik it. Have a machinist test the seat of the valves. Have a machinist check the valve guides.

Fuck sodium filled.

[Oregon72]

Fuck sodium filled.

Chi, tell us how you really feel about sodium filled valves??



I agree with chi, have the heads vacuum tested and looked over by a pro. I believe you want to have them cleaned so you can see any deal breaking cracks in the combustion chamber and in the exhaust ports. Perhaps you could have the cylinders honed and be good to go. Then again, there is good peace of mind in getting a new set of pistons and cylinders. I would recommend getting the full harmonic/dynamic balancing job done on the rotating mass by a reputable machinist. A good trust-worthy machinist will be very valuable to you during your build. Is there any reliable machine shops near you in Montana? Lots of choices to make for you - only one thing is for sure right now - You won't be able to reuse the crank

[Bleyseng]

My 2 cents. Check for recessed valves, doesn't look lik it. Have a machinist test the seat of the valves. Have a machinist check the valve guides.

Fuck sodium filled.

ditto

[Amskeptic]

My 2 cents. Check for recessed valves, doesn't look lik it. Have a machinist test the seat of the valves. Have a machinist check the valve guides.

Fuck sodium filled.

ditto

Who said filthy language was OK in the Technical Forums? You can say for example, "in my experience (do you have experience with sodium-cooled valves?) with sodium cooled valves, I found that they had a tendency to snap at the stems" or whatever your experience with sodium cooled valves has been.

In the realm of experience with sodium cooled valves, they are wonderfully capable exhaust valves that people diss because they are expensive. Very Expensive.
Colin

[chitwnvw]

Feel free to delete the spirited expletives, I was already quoted when I noticed I was in the tech area. I apologize. It was my oversight.

I have experience with old fashioned valves which are perfectly adequate...IMHO.

PS:

people diss because they are expensive. Very Expensive.

That was my point. If you are a bottomless money pit, go for it. Otherwise, more bang for your dinero spending that money in other places. Again, IMHO.

[Bleyseng]

My 2 cents. Check for recessed valves, doesn't look lik it. Have a machinist test the seat of the valves. Have a machinist check the valve guides.

Fuck sodium filled.

ditto

Who said filthy language was OK in the Technical Forums? You can say for example, "in my experience (do you have experience with sodium-cooled valves?) with sodium cooled valves, I found that they had a tendency to snap at the stems" or whatever your experience with sodium cooled valves has been.

In the realm of experience with sodium cooled valves, they are wonderfully capable exhaust valves that people diss because they are expensive. Very Expensive.
Colin

ok, in my personal experience mostly with 914's as they came with them, THEY SUCK if you let them get too hot via lazy valve adjustments. They are hollow stemmed filled with sodium which is nice but if they start stretching then they have a bad habit of snapping off at the head and bouncing around the combustion chamber. It was solution due to keeping the combustion chamber temps high via the crappy cam and restrictive exhaust. In combination with VW's crappy seat material selection made for weak head and valve life.

[whc03grady]

Thanks for all your thoughts on sodium-filled valves, but the price tears it for me; I didn't know they were anywhere near as expensive as they are.

I'm working with a machinist in Missoula so far. He used to be a ACVW guy in Denver, so he could know what he's talking about. Then again, maybe not; it's difficult to know who to trust and even what questions to ask.
He said he wouldn't bother doing anything to that head (assuming it passes the leakdown test). Me, I'm not so sure. Isn't it bad that the surface got beaten up a little? If it were scraped flat again, wouldn't that alter its volume, however slightly, and throw other things off? And what about that piston that did the beating? Just leave it alone? Can pistons even be reconditioned?

[hambone]

If it were me and I was rebuilding an engine, I'd have the heads rebuilt too. They are critical.
Afterwords do the CCing and deck height and CR calculations. Otherwise who knows what the hell you have as a combination? Air cooled is precision.
But I sure don't want to piss anyone off again by imposing my nuerotic carefulness!

[Amskeptic]

ok, in my personal experience mostly with 914's as they came with them, THEY SUCK if you let them get too hot via lazy valve adjustments.

Well geeze louise, VW buses suck if you drive them into Mitsubishi Eclipses.
Type 4 engines suck if you drive them with missing tins, oil leaks and filth.
You deserve a sucky result if you do sucky valve adjustments.
How many mechanics know that sodium cooled valves must be set at .008"?

They are hollow stemmed filled with sodium which is nice but if they start stretching then they have a bad habit of snapping off at the head and bouncing around the combustion chamber. It was solution due to keeping the combustion chamber temps high via the crappy cam and restrictive exhaust. In combination with VW's crappy seat material selection made for weak head and valve life.

This is clearly the old Raby rant. "Restrictive exhaust" "crappy cam" and I am just now getting to know the BobD at 75 mph with long hills on I-95 at 92* (can't wait for the 120* of summer deserts where I will wish I had sodium cooled exhaust valves . . . ) and the stupid oil still won't boil off the moisture.
Colin
(tell me about this crappy seat material, what was crappy about it? I had a soft seat in the Squareback that increased valve cooling enormously as it eroded. Have you found seat material eroding in Type 4 engines? Or seats dropping out due to operation error? That is not a material issue. That is a Leaving Design Parameters Issue. I find that it is the crappy mechanics that make a VW engine behave crappily)