Use Rev Limiter or Let Carbs Limit Revs?
 

My engines started out as Gen VI 454 mags 1997. With the help of RMBuilder and new parts from the cams up I can turn 6100 rpm before the engines fall flat due to running out of carb (750 cfm). I have 6000 rpm rev limiters to go with my Performance Distributors (DUI). I intend to prop for 56-5800 rpm wot. I would like to forego the rev limiters just becasue it would be one less thing to fail. Do I need the rev limiters, if the carbs won't let it get over 6100 rpm? Opinions welcomed. Brian

I would think motor will break past 6100 when not under load. Like when boat airs. This could be costly if you make a mistake and don't throttle back. Your valve float will sound similar to a rev limiter. But prob not get the same results. LOL .... 2¢ install rev lim

Rev limiters. Otherwise you risk ruining a motor if you have drive failure, coupler failure, etc...

Rev limiter...I have pics around somewhere of the 468 in my buddy's jet boat...no limiter..got some air at WFO, pump unloaded...cam came out in 5 pieces. Only good parts off the engine was one head, the intake, and the carb.

Cheap insurance.

Break a vert shaft at WOT and see where the RPMs go.

You need a rev limiter. I think you are misunderstanding that the carb size does not limit the revs. Your just out of horsepower at 5800 RPM. With no load, it will rev well past that, until she blows. If your carb was truly limiting your revs, you would not have enough power to even get on plane.

Hope this makes sense.

Got the Rev Limiters in hand, so will install thanks.

RT, for the sake of learning. This was "free reving" in neutral to 6100 wot. So, why wouldn't it keep reving on past 6100. Is 6100 where I poop out with air and gas to rev higher? The 750 cfm carbs calculate out to about the 6100 rpm that the rpm's go flat.

So when you open the throttle all the way in neutral, it will only hit 6100?

Have you tried them under load? The carb calculations are correct for that size engine, but 750cfm should give you enough Carb to make horsepower at 5800, not choke the engine off.

If they will only free rev to 6100 you either have an intake restriction, a rev limiter already installed, or a major tuning problem. Are you sure your throttle plates are opening all the way?

Another thought... are you sure your cams are properly degreed?