Purpose of a blow out ring?

[delawarerick]

What is a the purpose this was on the motor when I got it with an over the hub prop. Making progress on the project it's tough with the budget but it shall run. Pictures for a laugh will be in the lounge but I will guarantee 70+from a v4thanks Rick

[EMDSAPMGR]

This is an early OMC chopper, first made for the 135/140 V4 crossflows. Originally sold painted silver, it was called the "silver streak."
Most of us old timers have seen these years ago. Sold only in a 23 pitch. The thing is that to work correctly, the silver streak also needed this metal blowout ring. It acted as a forward thrust washer. Kept the exhaust focused close to the center hub, so the exhaust did not foul the outer tips of the blades. The V6 SRX was later patterned after this prop-but did not use the blowout ring. Many of today's blowout rings are now plastic.

[delawarerick]

Thank you for the answer I have a 23 srx and a 27 cleaver is there any need for using a ring on either of these props?

[racer]

By extending the lower unit the ring helps to prevent a low pressure area on the port side (right hand prop) of unit that can actually suck exhaust forward at speed when the unit is in a slight crab position. A slight movement in the unit can then release this exhaust back into the prop creating blowout. A longer unit is also less likely to crab.

[EMDSAPMGR]

The blowout ring is part number 323411. That part was superceded to 318841, which was superceded to 127084. That latest part number is still current, but is on Back order at Bombardier. It is possible the 084 part number may have been redesigned and is just the forward thrust washer. You'd have to visually look at the current 084 part. It may no longer have the exhaust part of the ring. So, unless you can get hold of the early part number, you won't be able to test the thrust washer with the exhaust ring. I'd be inclined to run with it.

[delawarerick]

Thank you for the replies I have 323411 it will be on when I test run waiting for the axle for the trailer and then to the water. thanks again Rick

[Magcat 62]

IV heard 10 different descriptions of what a blow out ring is. the small groove at housing end? some are plastic? an omc chopper? i cant take any more i always thought it was that wierd thing on the end of prop hub? is it removable? im confused.

[EMDSAPMGR]

The blowout ring for the above chopper does two things: keeps the prop from blowing out at high speeds, and helps control/regulate the uncontrollable rpm's from the prop when coming out of the hole. Most of the later OMC blowout rings: 126669, 346462, 350626 are plastic. Some clip inside the gearcase when using the small hub renegade 4-blade bass props. These props have a smaller horn diameter than that of the gearcase. On heavy, bassboats with lots of hp, the props tend to spin on the holeshot, instead of pushing the boat up on plane. These vent rings limit the exhaust gas that fouls the prop so that a heavy bass boat can get up on plane. You don't see them used much, but they are effective. They are sold separately and come for various props and gearcases. The 126669 was brought out by a factory service bulleting 2262. The engineers designed it specifically for severe prop ventilation on service replacement gearcases -see the bulletin. Not for Magnum gearcases.