'True' Factory Compression Ratio's

krazykuda said

That makes more sense.

If you do the compression calculations from the raw specs in the service manual, they don't add up... Machining tolerances....

The only to know for sure is to check it yourself like my write up in the how to section...

Click to expand...

Correct,

The Factory 'advertised' Compression-Ratio is way off the charts when compared
to 'actual' measurements.

Back-in-the-Day,

That is why Mopar recommended milling the Cylinder Heads {#2843906} for the
1968 and 1969 '383' {.030"}.

It really got you back to around {10.0 to 1} Compression Ratio, without touching
{decking} the Cylinder Block.

And you were fine, with Valve-to-Piston clearance, with the recommended Street Performance {484/284} 'Hydraulic' Camshaft.