CR difference between heads, grinding chambers

[Beetsme]

Two quick points first: I have no idea what I'm doing. I don't mind screwing something up to learn a little.

Reassembling the stock motor in my '73 std. This is extreme low budget, so while I'd love to go buy new heads (They're so cheap!!) that isn't an option right now.

So I'm reusing the heads. I'll bash in some exhaust guides to ease the guilt. One measures 49cc, the other at 47cc. Motor previously was running .050 deck with single shims under the cylinders, so 8.0 & 8.3 compression is what the calculator tells me. Higher CR was on the 1-2 side.

Bearing in mind this is in no way a performance motor, should I care about the difference? If I attempted to fix it, should I stack shims (I understand this not to be preferable), or should I grind out the chamber a bit on the smaller one?

How much could be safely removed, and what area should I destroy first? Or should I just stop over thinking and bolt it togther.

Yes, it use to run "fine". Yes, it ran hot, but I had a multitude of other cooling system issues that I'm trying to fix at the same time. The longer term plan is get it back to running and revisit a total rebuild in a few years.

[modok]

#3 tends to run hottest and #2 runs coldest.

See what I'm saying?

[Beetsme]

You are saying its normal to have a difference per side? Or not to worry about it because the higher compression is on #2 side?

[FreeBug]

[modok]

It would be nice to have them all within 1cc, but probably no benefit to get them any closer than that, provided you put them back on the same way.

We discussed where to grind a few times, there are different opinions on it. In any case 1cc is easy. This is one.
https://www.thesamba.com/vw/forum/viewtopic.php?t=567773

[orwell84]

I don’t know if that is a difference you could actually feel. I often read about engine builds where the deck height varies between sides. There a number of factors which can cause this and careful measurement can help tell you what it isn’t and maybe you can juggle things around and balance it out more. There is definitely a point of diminishing returns especially on a stock engine. But it’s also nice from a workmanship point of view to get things as close as possible. Whether it makes a difference on how you go down the road is hard for a relative beginner like me to judge.

On my current build, I was looking at side rod clearance. I had one rod where it was like .017” and the rest were like .014” or something. I considered juggling the rods around to make the numbers look nicer but it wouldn’t have changed much as they were all close and it turned out to be a journal that was a bit wider. Knowing when to call it good is important too. Anyway...that’s kind of how it goes.

[Pruneman99]

What heads do you have? Is there a step in the chamber? Is the .050 to the flat of the head, or to the step?

[Beetsme]

That was a good thread on removing material from the chamber. Thank you. The .050 is from the top of the piston to top of barrel. There is no step in the combustion chamber. I'm not sure what type of heads these are other than stock dual port?? They do have different numbers on them, but not any noticable differences. Sorry, didn't happen to have a better photo of them.

So obviously these heads aren't gold. I don't mind experimenting a little for the sake of learning..."Remember when you tried to save money and ended up just making scrap metal? Yeaaaahhh..."

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