Does anyone know if the Mark IV cylinder heads for the 365 mag and 330 "peanut port" heads have the same CC volume?
Gary

I believe they are both 119 cc or thereabouts. You can check the casting numbers on www.mortec.com.

.. ..also casting will vary from what the OEM specs are. One pair listed as a 119cc may be 122cc and another set may be 124cc. If you are boderline on a safe compression ratio your best bet is to have the heads CC'd.

Thanks,
Just wanted to know if swapping heads would change the CR.
Gary

Magnum heads should be Rectangular ports. The best bet would be to get the casting numbers and check mortec. I replaced my peanut port 118cc heads with a set of Large Oval (820s)110cc heads and picked up compression. You can CC the heads yourself with a piece of plexiglass some grease and a surenge. This will give you a pretty close estimate. You could have your heads milled down and pick up compression you may drop 3-4 cc's and pickup .3 compression points.