Most 350 heads had 64cc combustion chambers. On pre-86 307's, it would bump you up to 8.2 (from 8.0:1). post-85 307's it would get you 8.4:1. On post 85 307's you'd have to change your intake to either the 350 intake or an A4 aluminum. The ports are tiny on post-85 A5 intakes.
More compression, bigger cam, better flowing heads, improved intake and exhaust, supercharger, nitrous oxide injection.
Yes. You'll need some compression, good heads, and the right cam. Best to consult a professional to avoid doing it more than once.
motor will not run completely the correct way. motor my not be as strong any more
The more boost you use the lower compression you want. Higher compression with boost leads to detonation which leads to excess engine wear and damage.
The Engine - more specifically - the heads.
A power adder such as nitrous oxide injection, a supercharger, or a turbocharger would be the easiest way to get to 500. If you want to do it without a power adder, you'll need more than 10:1 compression, good heads, and a roller cam.
Hard to say without more information, but in general the decreased compression from the larger chamber heads would probably drop it 10-20 hp from stock.
More than likely your timing belt is not installed correctly so you have open valves when they should be closed to have compression...
A compression test would be the easiest way to determine. If you have little or no compression in two or more adjacent cylinders, you either have a cracked cylinder head or a blown head gasket.
If your car seems to be losing power, you should check the compression of the engine.A patient who has received severe burns may require a compression bandage while he heals.Osteoporosis may cause compression fractures as the bones weaken and become more fragile.The forces of tension and compression work together to make bridges strong enough to hold considerable weight.
More than likely the engine is missing on one or more cylinders and unburnt fuel is being forced past the piston rings on the compression stroke.
if it has the double hump heads..more than likely 350hp. If not 250hp