Is it possible to be able to run 11.3:1 compression on 91 octane? I would have a custom camshaft designed and motor will be setup at zero deck height.

Make sure the cam grinder understands what the engine is being used for and what it is equipped with.  They should be able to give you a cam that will make it work.

Custom cam & proper tuning....you will be good to GO!....

Would I see a performance difference between 10:1, having to run a smaller camshaft and less timing?

Depends on the cam....

You will more than likely want to either have a smaller lift or shorter duration grind than what you would normally use, but can be done.

I agree with talking in depth with your cam guru...

GT

What about running a more normal lift/duration with a very close lobe seperation (106*) to allow some loss of compression due to overlap.  Granted it will cause a narrow power band and very rough idle.

What about running a more normal lift/duration with a very close lobe seperation (106*) to allow some loss of compression due to overlap.  Granted it will cause a narrow power band and very rough idle.

With dry exhaust this would be ideal. Wet exhaust, no bueno...

And I mean DRY exhaust.

I already have a shutoff valve that I'm plumbing into my setu :banghead:p. My only debate left is the 4.5" or 4.3" stroke in the stock block. Will the shorter stroke last longer and be able to handle more abuse or does it really matter?

4.500 all the way!

X2

Is it possible to be able to run 11.3:1 compression on 91 octane? I would have a custom camshaft designed and motor will be setup at zero deck height.

Although it is technically possible to have 11.3:1 c/r and run on pump gas in a naturally aspirated engine combo, it is very tricky and not a plug-and-play deal.  Too much spark advance and/or too lean on the fuel and the BBF will detonate a hole into a piston or two without your ever hearing it. The power advantages with increased compression ratio is a game of diminishing returns, and so 10:1 is much, much safer than 11.3:1 while the drop in power between these two c/r's is not something that you will feel in the seat of your pants with a jet pump behind the engine.

LO

My only debate left is the 4.5" or 4.3" stroke in the stock block. Will the shorter stroke last longer and be able to handle more abuse or does it really matter?

The 4.5 stroke fits.  4.3 stroke is the overall better package for the 385 Series blocks and will have greater longevity, balance for less, have slightly greater structural integrity, better rod ratio, better ring pack (in some cases), etc.

I think Moses just showed up with a new set of tablets.       I imagine the waters will be parting any minute.

never heard that before 

  Funny stuff! But true. You're in the bestest hands in the world with Dave and Paul, to be sure! I stand corrected on my earlier post. I meant it for ME and noone else.

All us motor heads easily, and collectively, say "Yeah, go ahead and do it, and then also do this while you're at it"  when it's not us that have to live with the result of some truly unuseable monster we've built, or grenade in many cases!  . I'm guilty as hell of this.

I'm not throwing Nordie under the bus here, more me throwing MYSELF under the bus, but he is really experienceing the results from that. Killer motor, blower cam specs, dry headers, etc, etc. One bad ass BBC. BUT, the everyday use, ease and flexibility of maintenance, just being able to simply launch the damn thing with many on board and have a fun day on the water is an excercize in futility. All that is gone now. Now, kids, or you, will get burned on the pipes if you get within 10 feet of them even an hour after beaching and on the water you're not only looking around while driving, watching guages, running the throttle, F/R lever, Diverter, and NOW you add in a water valve for the headers depending on RPM......Takes a lot of the pleasure out of a pleasure craft.

Ignore my earlier post liking the idea of the blower cam. Listen to Paul and Dave, drop the C/R (Mill off the pistons, cheaper than new ones if they're good pistons), use a lil more agressive STD cam available everywhere if max HP is what your after. You will get far more HP from proper cam selection for the intended real life useage, induction system planned, C/R that is flexible, and a bottom end to support the package than C/R will give you alone on pump gas. Just MHO.

Me? Yeah, custom blower cam on my Moo, among other things, but I got 5 others here to play around with everyday as well!  That boat is designed to do and prove something and accomplish only ONE thing.   

Ray

On the contrary, it was the highest compliment I could come up with on short notice.   Every post I have ever read from you is helpful and informative.  Please take no offense, none was intended.