mike tkach

iTrader: (3)

rick,the ring gap varies depending on what brand of ring you use.generally on a blown gas engine about .006 gap per inch of bore[4 inch bore=.024 gap.]always follow the recomendation that comes with the rings.i always replace the chain&gears as a set,i like cloyes true roller billet set,as far as oil pump,i like the mellings select.when you buy gm performance parts,you are actuially buying aftermarket parts made for gm,this holds true on app 90 percent of gm perf parts.good luck with your build.

Raylar

As an experienced engine builder I will toss in my "of sometimes questionable value "-two cents here.

On assembling short blocks for ENDURANCE marine performance engines, its actually more important to pay very concise attention to the block machining, clearances, fitment ,preparation and cleaning than just talk about the great aftermarket parts for the build. The importance of a straight mainline, square even decks, straight to the mainline boring and concise proper honing and fitting of all the various parts cannot be stressed ENOUGH! Good simple de-burring, setting deck heights, piston to bore clearances, bearing clearances, careful cleaning after machining and prep, etc.,etc.,etc will yield many more hours of trouble free operation.

This is why most good professional engine builders have better success ratios on big horsepower marine ENDURANCE engines than private owner builders on par. Just the equipment, tools, machines and years of experience are very expensive and are required provisions for successful engine builds.

There, now that I got that piece of wisdom off my chest!

Its time to add value to your question.

My experience with supercharged engines, which is not huge, but reasonably successful has led me to start with the right material and type for supercharged engine ring sets. We have had great success with the Total Seal Hellfire ring sets for supercharger use and on your bore size a .028" top ring gap and a .030" second ring gap should be just about right provided the piston set has an accumulator groove over the second ring. If not the second ring gap should probably be opened +.002" or so to make sure pressure does not create ring flutter on the second ring. Make sure the file to fit work is done by someone experienced on a good machine and the corners are properly dressed before assembly and use. DETAILS-DETAILS-DETAILS!
You or your shop should also pay particular attention to the final hone pattern and finish as it will play a huge part in ring seal and life. Your performance ring manufacturer would have the best specs. on their particular ring package

As for a timing set you should definitely make sure your camshaft is properly dialed in a set to its best timing for your use, this is best accomplished with a nice true roller hex-adjust set form Cloyes which has strong CNC billet gears and special chain.

As for an oil pump, the Melling Select 10778C mentioned by others here is definitely the best unit for your use.

Hope my advise is helpful and good luck in your build. Just don't cut the corners for a flawed budget or skip the important details and end up buying your new short block twice!

Best Regards,
Ray @ Raylar

Panther

Ray, what do you like about the Hellfire rings?

I was advised against using them by some reputable builders.

I've also seen a lot of debate on the 2nd ring gap. There doesn't seem to be any evidence one way or another and each builder seem's to have their opinions on it.

As for machine work, there's no doubt the equipment is expensive. I don't own any machinery but have an excellent machine shop I farm all my machine work to. At the end of the day my dial bore gauge and torque wrench works as good as anyone else.

I've done work myself and also paid others to do it over the years... It all depends on cash flow....

blownjet 468

these rings are supurb for blown applications-IF the proper
cylinder finish is achieved- best with a "plateau" finish ie:finer
than what you would generally use for a standard moly faced
ring set....