Square ports

[chitwnvw]

So I have the 39 mm intake valve on both heads. I doubt anyone is interested in a 79 head with the larger intake valve. Do any of our AC Vanagon gurus have any idea the vanagon combustion chamber got smaller and the intake valve got larger?

I guess, I'll see where the deck height w/o shims lies and crunch the numbers. I'm not going to go with a 6:1 CR.

[airkooledchris]

sorry to hear that BOTH of those heads ended up being unusable. they were both Vanagon heads originally, with about 20k on a rebuild done by AVP. it never failed, but it was a gutless wonder. no huge surprise that it was running with two heads both not worthy of a rebuild.

the last two square port heads in my parts stash are AMC's with no part numbers. I don't know if there are any differences in the AMC's or if that would match one of the two you have now. if it would, let me know. i don't know much about heads, but the exhaust valves are stamped VW with a little S on them.

[chitwnvw]

So by my calculations with a 53 CC combustion chamber and a 15 CC dish in the piston and .04 deck height give me a 7.6 CR. So I can't really fly cut these heads without effectively reducing the deck height to less than .04. On the other side if I set the deck height to .06 and manage to remove 5.5 CC I will match the 7.6 CR.

Funny I checked deck height last night and one side of the engine was at .01 and the other at .02.

[Gypsie]

Funny I checked deck height last night and one side of the engine was at .01 and the other at .02.

I have been told that this is not uncommon.

From personal experience I will suggest that you triple check that you don't have any extra cylinder base shims stuck on there. (the ones form the seal kits are .010) just in case. Mine was hiding under a bead of "permatex camo".

Where the heck will you find 5.5 cc's to dig out. You must post pix when all is said and done.

I am all atwitter...

[bajaman72]

So by my calculations with a 53 CC combustion chamber and a 15 CC dish in the piston and .04 deck height give me a 7.6 CR. So I can't really fly cut these heads without effectively reducing the deck height to less than .04. On the other side if I set the deck height to .06 and manage to remove 5.5 CC I will match the 7.6 CR.

Funny I checked deck height last night and one side of the engine was at .01 and the other at .02.

All these numbers make my head hurt :( wish I was able to figure this stuff out.

[chitwnvw]

Where is it 'safe' to remove material from a piston to balance weight?

[Gypsie]

I removed material from the apron "ears" (the part that looks like a mountain (where the rod pin penetrates) but have seen it taken from the bottom of the "cup".

I say be aware of making any area too thin and take material evenly. If you are taking from the apron ears, take from both sides on both ears.

2cents.

[RSorak 71Westy]

Only 2 places. Mill material off the top, this obviously changes comp ratio, or if this not an option from the inside. The pin bosses can be rounded, if they have square edges.

[chitwnvw]

What about the wrist pins?

[Gypsie]

I wouldn't

[RSorak 71Westy]

To taper the inside of the hollow ends of the wrist pins is fine.

[Gypsie]

Since the pins are permissible I would think that would be the optimal spot as the material would be heavier albeit harder to remove. Careful now, don't you go dentin' things up now.

[chitwnvw]

Strangely, the Vanagon heads are 3 thousandths to small to accept the Brazilian Mahle cylinders. Wet sanding them with 400 grit to get clearance.

Good grief ACR had this right, it is slow and methodical to get these combustion chambers all the same.