SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: SnoProCT on May 14, 2014, 04:12:33 PM
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So I picked up my first jet boat, a 1986 Daytona Sprint, and to power it I have a Chevy 489 Stroker with forged rotating assembly, 11.5:1 Compression topped with a set of Merlin Heads. The cam that was in the motor had grooves worn in it with mechanical roller lifters, the rockers took a hit as well (looks like one has been off a few times). The motor was in a car, and will now be in a boat, I have had a few suggestions from some rookie locals, but would like some more input from someone who has experience. Another question is, what limits your RPM, or what is supposed to anyway, the cam or the pump?
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Pump
-beerjet-
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Got a couple questions that will help us guide you in the right direction.
Do you want to stay with a mechanical roller?
Are you interested in a Hydraulic roller?
What intake and carb(s) are you planning on using?
Are you going to run race gas, alcohol, E85, nitrous?
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Depending on what you plan on using the boat for will also determine what cam would be best for your application.
Assuming it'll be a typical river racer hot rod and you don't plan on pulling a tube or skier much I'd recommend the Comp Cams 11-702-9 if you want to stay with the mechanical roller. It's a decent size cam without being so big that it's hard on parts. It gets expensive to replace valve springs every season or more depending on how much use it's getting.
Now if you plan on drag racing or trying your hand at roundy-round I'd go with something a little different.
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I was hoping to keep it more of a river hot rod than strictly a drag racer, one of the locals suggested Howards Cams HRS CL120405-12 Hydraulic roller setup, I am open to all options, would like to make most power, but also keep it reliable. I have a Dart intake, and Dominator Carb, was planning on mixing half and half race fuel and high octane. It looks like it was running a little rich so my plans are to take the carb to a local speed shop and have it jetted properly. Thanks again for all the helpful input.
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Like crewchief is saying, it all has to work together, from the air coming into the carb, to the spent gas exiting the exhaust, carb, intake, compression, exhaust are all part of the equation. Each piece helps pick the next piece. Not knowing what your heads will flow, it's hard to suggest anything. Then where do you want to make power at in the rpm range, above 4000 or done by 5000? Sorting all this out ahead of time will get you the results your looking for instead of people just guessing at what they think you need. Have as much info and specs as you can on what you already have and then contact someone like Clay Smith cams, or Chris Straub Technology's. These guy's will crunch the numbers and get you exactly what will work for your build. Other people, like the local speed shop are just guessing. If they're are not asking you these questions, then they don't know what they're talking about. JMO. Good luck
http://www.straubtechnologies.com/ (http://www.straubtechnologies.com/)
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Thank you all for the awesome responses. I will do exactly as you said, find out specifics on every piece that I have and then contact a manufacturer.