First Cruz

[RH]

First time out in my new to me Spectra 18 460/JE ran great here are a few questions .
1. Cruised at 3500 rpm went fast 4000 to 5000 where I let off what is the danger zone [red line] with this combo ?
2. Alot of weeds in the lake had to stop alot to clean them out is there a different grate that would keep weeds out?
3. Engine temp. was at 110 where should it be for best performance ?
4. Other than shooting a big roost how do I use the place diverter ?
5. What is the best thing to use to get the lake scum off the white hull [tried 409 , alcohol]
Had a great time with my first jet ! Thanks Randy

[OmegaBitch2]

RH, 1- what is your combo? stock mill, impeller cut...etc.2-weeds ,well you got me on that ,dont usually have a problem with those up here!3-engine temp should be minimum 160,with 180-190 prefered.4-if you have a gps use it ,they help quite a bit, so does the tach.do you have a trim gauge?speeds up return to the sweet spot,this again depends on boat weight(empty/full)(passengers..etc.5-I find spray 9 works the best for me.Anyways Im sure that there are some various other ideas out there,but gives you a place to start!! Roosters away!!! :D

[skeepwerkzaz]

RH welcome to Jet life. Congrats on the new boat, you will have a lot of fun. It is really hard to jet jets to reach operating temp since you are cooling with cold lake water, but fiddling with thermostats does help. Weeds are a bitch, try to steer clear. The place diverter is a learned trait, the GPS idea is a good one, if you would like I could go out with you sometime with mine and we will find the sweet spot. There is some stuff called gel coat restorer that works awesome on hulls to clean them, I have had very good luck with it, and is available at most automotive paint stores. I have been jet boating since I was a little squirt and might be able to give you some insight if you wish, I am in Sonoma right now and would be happy to help out. The most important thing is to HAVE FUN. Good luck.

[RH]

The boat is a Spectra 18 2050lb. dry plus maybe 600lb. people , gas etc. total say 2700lb. 460 Ford rebuilt with about 200hr don't know if it is stock, the receipts I've got with it show the following
460 comp., rv cam 22915 ,edelbrock manifold 2166 ,accel distributor , edelbrock carb. unknown size . Berkeley 12je rebuilt parts plus super stock blueprint , impeller cut to comp-a dia that's about all I know hope this helps thanks Randy p.s. carb is a 750 cfm edelbrock on a performer manifold
[ August 06, 2002, 10:29 PM: Message edited by: RH ]

[RH]

Any input on my weed problem ? Can I make a screen to go over the grate with out screwing up the flow . Thanks Randy

[HBjet]

OmegaBitch2:
3-engine temp should be minimum 160,with 180-190 preferedI have to disagree with this. I recommend your engine temp to be between 140-160. If you keep it between there you won't run into any problems and have good performance.
HBjet

[OmegaBitch2]

Colder engine temperatures increase engine wear.There is a certain temp range that engines are designed to run at.Horsepower equates to heat,the more heat you can hold in a cylinder the more power you produce.Talk to some knowledgeable engine builders.You just dont want things so hot that detonation sets in.Accelerated cylinder wall wear occurs at colder operating temps,...check it out.Thats why all the new stuff runs thermostats. I wont even get on it in my boat till Im up to 160.

[Rexone]

While marine engines will run fine in the 140-160 degree range, its really not optimum for a number of reasons. 180-190 is ideal. It does a number of positive things. It gets the oil temp up around 210-220 where it should be to lubricate properly. This in turn burns off unwanted internal engine water condensation which is very common in cold water source cooling systems (and not good for engine parts). It creates ideal combustion temperature for good power yet is not hot enough to cause unwanted detonation. A "properly plumbed" lake water source system will not have any problems at 180-190 degrees. Water does not boil at that temperature so no steam pockets are possible (again if it's plumbed properly). Usually if a boat has a cooling problem of some kind at 190, its a water routing or supply problem, not one of too much temperature.
Not trying to argue anyone's posts here, just passing on what we've learned building engines, racing many types of boats, and manufacturing cooling system parts for many years. Hope it helps.

[RH]

Would a thermostat kit take care of the temp. issue ? Someone told me I should have two gate valves in the system also one intake and one the exit they could not tell me why but said it is pretty common . I don't have a stat now did boats from the 70's not have them ? If low temps are a problem why were they built without them ?
skeepwerkzaz Thanks for the offer I'll keep that in mind. Thanks to all Randy

[Rexone]

Yes thermostats work very well on jet aps. Take a look at our website. We've sold litterally hundreds if not thousands of the 160100 model for boats similar to yours. The gate valve method is a little sketchy on the intake. You can get the temp set right for say top end, then it's too cold running slow, get it right running slow, then it overheats when you hammer it. Then there's alway the worry someone will move it or it will move by itself and fry the motor. Thermo kit is much better solution. Why the older boats didn't have them is an excellent question that I don't have the answer for. I guess no one knew any better or just didn't give a crap back then. Hope this helps

[cyclone]

I have to put my two cents in on this one. When I had my 502 in my truck dyno'd, the water temp was set at 180 degrees and the motor made 571hp and 630 ft/lbs of torque. But then they did a "boat test" during which they dropped the water temp to 140 degrees and the motor promptly made another 40 hp and 50 ft/lbs of torque on then next pull. So i'd go with the numbers and run my motor cold. The dyno don't lie.

[HBjet]

RH, I use a pressure regulator from the pump. Regulating the pressure of the water entering the block. The pressure remains consistant all the time. (unless your pump at ldle pushes less then what your regulator it set at) I then use a valve on the water exit line. The reason for this is to adjust your water temp. The more you open it, the colder it's going to be, and vice versa.
You can go the thermostat route, or you can go with a requlator. I personally like the regulator setup.
OmegaBitch2:
Talk to some knowledgeable engine builders.I did.
HBjet

[RH]

HB ,
Can pressure be a problem in the cooling system ? What type of regulator is it? Is it made for a jet pump ? what do you keep it set on and what do you like better about your system over the thermostat . Thanks Randy

[Froggystyle]

How do you run a thermostat with water cooled headers? My Lightnings need water right at startup or they will fry. How do you maintain water in the block, yet still get water to the exhaust?

[Lightning]

I had some issues with engine temp. My engine came without a thermostat. It ran Too cold and the boat would not idle, engine die, etc... The boat was running so cold that the temp would not even register sometimes. I installed a thermostat kit and it solved all the problems. I guess it just depends on the particulars of the motor that you are running as well as the plumbing setup.

[Rexone]

Froggy,
Our thermostat setup has an internal spring loaded valve and a 4 port housing that allows water to circulate through the system prior to the thermo opening, thus protecting the exhaust, be it headers, manifolds, and also rubber exhaust hose on boats that have it. There's some diagrams of the plumbing on our website if you want to take a look.
http://www.rexmar.com/page160.html This is a link to that page. There's a basic unit diagram and a plumbing diagram that's taylored more towards aluminum manifolds but I have a diagram also specifically for headers. Let me know if we can help, I can scan that one and email it to you or fax if you like. We've had great success running these on jets for many years.