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Hi guys! I have a 13 y/o jet boat motor that has very low hours on it and I'm thinking about replaceing the valve springs. Does anybody have a recomendation for a mild cam. The motor is a gen 5 with stock heads, I'm not sure if that matters. Thanks for any and all help!
Good choice on replacing the valve springs to keep control of the valves near your max rpm! In a jetboat you never really see any rpm above 6500 rpm unless you are unloading the pump. Fully loaded, most don't see 5500 rpm unless you are making ALOT of power. Go with a cam that is not real big and maintenance free. :clover:
"In a jetboat you never really see any rpm above 6500 rpm unless you are unloading the pump."
Not True ... We typically run 7,400 RPM with the pump fully loaded ... Motor is rev Ltd @ 7,700.
"In a jetboat you never really see any rpm above 6500 rpm unless you are unloading the pump."
Not True ... We typically run 7,400 RPM with the pump fully loaded ... Motor is rev Ltd @ 7,700.
And the next sentence says.......... :notam: :D
1,500 or so Hp isn't really a "ALOT" of Hp ... When you pass say something like 3,500 Hp and MORE +++ ... Then, your getting into the Realm of having Maybe, "ALOT" of Hp. :D :D :D
"In a jetboat you never really see any rpm above 6500 rpm unless you are unloading the pump."
Not True ... We typically run 7,400 RPM with the pump fully loaded ... Motor is rev Ltd @ 7,700.
Jack...I hope you recieve this as the compliment as it is intended...there's NOTHING typical about your boat. :D
Hi guys! I have a 13 y/o jet boat motor that has very low hours on it and I'm thinking about replaceing the valve springs. Does anybody have a recomendation for a mild cam. The motor is a gen 5 with stock heads, I'm not sure if that matters. Thanks for any and all help!
Banshee...is your question referring to a recommendation for a cam, or just the springs? If it's just the springs, what's your cam, hyd. or solid?? :coffeycup
I recently rebuilt my 27 year old Mk-4 454 with cam advice/assist from DuaneHTP from High-Tech Performance. Entire Hydraulic kit from Iskendarian set me back $400, .565" lift cam, Isky Superlifters (floatproof to 7,000rpm), and 135lb set of double-springs with damper (3 coils total), also shims, retainers, poly-locks. The original cam measured up at .480" intake / .472" exhaust (GM High-lift hydraulic). I'm still breaking her in but she sure wants to run. There's my main idea. Mine still had to pull reliable duty as a ski/tube boat but I wanted to goose her some. Incedentally, I put on a Performer Air gap as well and kept the Nitrous. :D
I recently rebuilt my 27 year old Mk-4 454 with cam advice/assist from DuaneHTP from High-Tech Performance. Entire Hydraulic kit from Iskendarian set me back $400, .565" lift cam, Isky Superlifters (floatproof to 7,000rpm), and 135lb set of double-springs with damper (3 coils total), also shims, retainers, poly-locks. The original cam measured up at .480" intake / .472" exhaust (GM High-lift hydraulic). I'm still breaking her in but she sure wants to run. There's my main idea. Mine still had to pull reliable duty as a ski/tube boat but I wanted to goose her some. Incedentally, I put on a Performer Air gap as well and kept the Nitrous. :D That seems like an awful lot of seat pressure for a hyd. cam. Were the springs the 8005A's? Just curious.
steelcomp -
Your quite right, our dragster isn't all that typical ... Your comment was taken in the way you intended, I think. From the onset, I wanted to try something a 'little different' as I thought that would be the best way to build and race a really fast jet.
When we started all this back in '01, Mike wanted to transform the old boat into a faster racer and I wanted to start there and keep evolving to an even faster setup ... I wanted a R&D Platform that we could build on and learn something New from ...Also, I felt there was alot more to developing a serious, Safe drag racing program than just 'Throwing' alot of Hp to a boat ... be it a Jet, or V-Drive (Which I Like Too) ... You have to develope a 'Krewe' that performs in unison, on & off the track, and enjoys each other's company doing so ... Without that, some very bad things can happen.
I could go on and on about where our program is headed, but, I've already been too 'Long Winded' here ... Maybe some time along the way we can talk (when neither of us is tied up in racing activities as we were when you were last here) ... And Yes, I full well realize that our boat is 'Somewhat Atypical' and we are beginning to push the current envelope of jet technology ... It's all by design and I'm more than willing to share what we find out as we evolve with most people.
Back to the Thread Topic ... We run LSM Engineering springs (Gold Triples ... Japanese steel wound here in the U.S.) ... Expensive, but, they definately stand up to the environment we run them in.