Hi Steve, Your cruising RPM is going to depend upon a lot of variables and you haven't given near enough information to answer the question yet. Assuming your engine has a stock camshaft, the wide open throttle rpm should be about 4400-4800 rpm with a full load of fuel and a couple of people aboard, if the boat is propped correctly. Once the boat is correctly propped, the best crusing fuel economy will be at the minium speed the boat will maintain a full plane. That will depend upon displacement, hull shape, propeller diameter, etc. 3000 rpm is an okay ball park to play in until you make sure everything is set up correctly. 165 degrees is fine for a coolant temperature. If I remember correctly, Chrysler put 160 degree theormostats in fresh water cooled engines and 140 degree thermostats in raw water cooled engines. Oil pressure should be at least ten pounds of pressure per thousand rpm. Engines have the best longevity if then can stay between 180 and 200 degrees. Lower than that and they wear rings and bearings a bit faster than they should. Marine engines often run cool, because they are set up to do okay in the Gulf of Mexico with 85 degree water and a lot of Uniflite owners in the Pacific North West are running them in 40 to 60 degree water. I have a 27 Express Cruiser with a single Chrysler small block. Before I rebuilt it, I ran from Petersburg to Juneau (105 nm) at 15 knots. I cruised at 3400 rpm for about seven and a half hours, maintaining about 45 pounds of oil pressure and about 145 degrees of coolant temperature on arrival (130 degrees on departure). That is too cool as far as temperature goes but I run in cold water and I have a large heat exchanger. I've made this trip several times with no problems. Hope this helps.
John --- On Sun, 3/8/09, steve <[email protected]> wrote: From: steve <[email protected]> Subject: [UnifliteWorld] questions To: "UnifliteWorld" <[email protected]> Date: Sunday, March 8, 2009, 10:32 AM Hello; I have recently bought a 1972 Uniflite Salty Pup with a crysler 318 and direct drive. I was woundering if someone had some advice about a few basic questions. this is th first gas powered boat that I have owned. 1. What should the engine rpms be at an on-plane cruse? what is the upper range of RPM that you would be comfortable opperating the boat at for a few hours. 2. What should the engine temp and oil pressure be at idle Vs cruse speeds? Any advice would be very helpful Steve --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "UnifliteWorld" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/UnifliteWorld?hl=en -~----------~----~----~----~------~----~------~--~---
