I distinctly remember reading about different factory volumes for 1.9
and 2.1 heads, with 1.9 being smaller.  So yes, there would be a
difference in compression as Scott mentioned.

Also I've read about some cheap aftermarket pistons yielding lower
compression due to higher wrist pin location.

On 10/13/08, John Bange <jbange@gmail.com> wrote:
>> I have heard that AMC offers the same head for both the 1.9 and 2.1.
>> Which
>> means ..........they must compromise on the combustion chamber volume.
>> I believe, that if you increase the bore of any engine...........and no
>> other changes, you raise the compression ratio.
>> This is why I suspect OE heads offer one for the 1.9 and for the 2.1 a 'C'
>> suffix on the part number.
>> This should also mean that if you put 2.1 heads on a 1.9 you'll have
>> ..........think I have this right ...........a lower compression ratio
>> then
>> before.
>
> I think the only changes between the 1.9 head and the 2.1 were
> structural. According to the Pro Training Manual, the 2.1 simply has a
> 7mm longer stroke (94mm piston, so 4.7 * 4.7 * pi * .7cm * 4 cyl  =
> .195 liters).
>
> --
> John Bange
> '90 Vanagon - "Lastwagen"
> '90 Vanagon GL - "Wiesel"
>

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Chris S.
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