how much horsepower

[420nitro]

Originally posted by 84gt347
How about a thick gasket to get 9.3 comp

I don't believe so, sorry.
Generally speaking when you run a flat top piston with good size valve relief you end up with a piston that has 1.5 2.5 negative cc.
Now looking at the Afr 205 heads, they only mention having 58cc chamber heads available. You can always have the chambers worked so they are bigger but, just to keep it simple, with that size chamber and being a 347 I would look for a piston to have about a -22cc dish piston. That should yield you a compression around 9 to 1.

Example:
For a 347 (4.030 bore and a 3.40 stroke)
Zero deck height
4.100 bore gasket size
.040 compressed thickness (common average gasket thickness between .035-.045)
-19cc dish piston
will give you a 9.29 to 1 compression.

You might have your piston in the hole xx amount or out of the hole for xx amount and will change your end result of your compression! So the example that was stated was just for an example purpose only to give you an idea so you can fine tune it yourself. There are a lot of other tricks to change compression but that example makes getting the new head gaskets easier because there are very common.

And yes I got way too much time on my hands!!