I have a 1977 19 foot tahiti mini with a stock 454 and would like to know whats a good comp. ratio to run at on  pump gas and how much hp if any would you gain just by raising the comp.

I have a 1977 19 foot tahiti mini with a stock 454 and would like to know whats a good comp. ratio to run at on  pump gas and how much hp if any would you gain just by raising the comp.

A lot of the time a good camshaft and timing set will be the largest seat of the pants gain, if your BBC is truely stock, you may find the cam timing is retarded due to the year, in the late '70's almost all of the Big Three had to retard the cam timing to be able to pass the SMOG mandates, this is actually most noticable on the 460 Ford, I am with Ralph 100%, 10.0:1 is more than enough with pump gas, the cam profile will actually raise cylinder pressures all by itself. Not much to be gained by CR itself, it would require a retarding of the ignition timing to prevent detonation, taking away any gains you would have made, you can get away with much more with a lower CR...

By the way, all gasoline comes from a "pump".   

Good Luck!

GT

As already said, 10.0:1 is good for compression. 

But if your considering rebuilding the engine there is a lot of performance gains available in the cylinder heads.  Either porting the original heads or up grading to a set of performance aluminum heads will help.

Some of the other things to consider are intake manifold, carburetor(s) and a good ignition system.

What are you starting with and what do you want to do when completed?