Im being told its not possible to run the short risers that are required when using s. choice when you are using a hi lift roller cam. This is due to the closeness of the injected water to the manifolds. Anyone have experience with this??
thanks ....sj

I'm running a hyd roller, .610/.632 lift, .234/.242 duration in a blown 502 with the Gil/Merc silent choice and not a hint of reversion.

At Stainless Marine, we recommend a maximum of 224 degrees duration at .050" lift. Any higher, and it will suck water when idling. The higher the duration number, the longer the riser must be. Worst case, you never put the cooling water in the ind\side of the pipe at all.

Jerry,

I took a close look at the picture of your silent choice setup, and it looks like your divertors run backwards compared to the ones on my boat. On mine, the outlet to the Y-pipe kicks back towards the transom. Did yours come like this, or did you modify them to work this way? It looks like the way you are running it allows for a longer riser, because the divertor is moved closer to the transom. If you modified them, how did you do it? I would like to run a set of longer risers on mine just in case.

Thanks!

Tom....

I am using Gil manifolds with the silent choice risers, been on for 20 hours, no problems yet. I'm running the crane 731 roller cam,226,230 578,610 lift . I think these numbers are close

Budman (Tom)

You are correct, the valves are modified. I bought a set of regular valves and did the modification myself for the reason you stated. It allows the valves to be back as far as possible, thus giving the risers as much lenght as possible also. They are the same config as the Corsa HP divetor valves. The y-pipe is not modified. Basically you cut out a section of the lower leg and turn it around and weld back in. I seen this done on the Fountains from the factory, but they do a butcher job of it in my opinion. I bought some alum. tubing and remade the lower leg to my standards. (All welds ground and smoothed then powdercoated high gloss black)

Jerry

US1 FOUNTAIN,

Thats a great looking job you did.

MY SETUP IS A LITTLE (LOT)MORE STOCK THAN US1'S.I AM RUNNING STAINLESS MARINE MANIFOLDS WITH CORSA DIVERTERS.MY CAM IS 224/230 DURATION @.050 - 510/515 LIFT - 110 LSA. AFTER EXTENDED IDLING WITH THE TIPS CLOSED IF I PULL A RISER THERE IS THE SLIGHTEST HINT OF REVERSION(VERY SMALL AMOUNT OF WATER DROPPLETS IN MANIFOLD)NEVER ANY WATER IN OIL.I JUST MAKE SURE AT THE END OF THE DAY WHEN SHUTTING MOTOR DOWN TO REV IT UP WITH TIPS OPEN TO CLEAR THE MANIFOLDS.I HAVE 50 HOURS ON THIS SETUP WITH NO HINT OF PROBLEMS.SOMTHING TO CONSIDER IS THE HEIGHT OF THE ENGINE AS COMPARED TO THE WATER LINE ON THE BOAT.REVERSION IS NOT ALWAYS FROM THE WATER BEING DICHARGED FROM THE ENGINE.IF YOUR TIPS ARE CLOSE TO THE WATER LINE A FOLLOWING WAVE CAN BACK FLOOD THE EXHAUST AS CAN JUST BACKING UP TO FAST AT LOW RPM.MAKE SURE YOU HAVE GOOD FLAPPERS.IF YOU WANT TO BE SAFE USE A CAM WITH VERY LITTLE OVERLAP (WIDE LSA).IF YOU DON'T HAVE THE SILENT CHOICE SETUP NOW I WOULD DITCH THE Y-PIPE AND RUN LONG RISERS WITH MUFFLERS.IN MY CASE I ALREADY HAD THE CORSA AND WANTED TO USE IT FOR ECONOMY REASONS.

Thanks! You ought to see it now. That pic was from last year. I have since powdercoated the valve covers and carb body red and added chrome float bowls, plus more purty stuff. Looks faster than it is this year.

US1,

How about getting that digital camera out and posting a close-up of those divertors for us folks on the board! My divertors came off of a Fountain (29 Fever with twin mag's), but I can't recall them having enough length on the lower leg to make that modification. Did you weld them up yourself? I'm assuming that the bushings and butterfly have to come out to keep the heat from damaging them.

I might like to try this trick this winter. Since my boat is a single I have an extra set to play around with.

Thanks for all the help!