1957 35hp rde-19c gas mileage

[seahorse44]

I went to the creek today and ran my seahorse about 2 miles alternating slow and fast ,mostly idling . I used 2 1/2 gallons of gas !! <br />No gas in the water ,very little and very little smoke . motor runs good except its a little rough at idle. carbs adjusted as lean as possible. I have a 10 3/8 X 14" prop on it until my 10 3/8 X 12 gets back from rehub. Just wondering if you fellers have any ideas on this gas consumption ? It on a 26' 6" riviera cruiser pontoon boat. Thanks for any help .

 

[Paul Moir]

Re: 1957 35hp rde-19c gas mileage

How long did you run going those 2 miles, roughly? These old engines are bad on gas for sure, but they aren't terrible. They're worst at idle through mid-range.

 

[rolmops]

Re: 1957 35hp rde-19c gas mileage

It may have a lot to do with the prop you use.I use a 10x11 prop on the exact same engine for a light weight 16 footer.This gives me 4500 rpm according to my tinytech tachometer which is very precise.It would not amaze me at all if you are chugging along at 3300 to 3500 while practically dumping unburned fuel into the water because your throttle stands wide open.You are pushing a heavy load with that machine, you might want to consider going to a barge prop(10.5x10)

 

[seahorse44]

Re: 1957 35hp rde-19c gas mileage

Paul Moir,<br /> Good to hear from you Paul . Well we probably run 45 minutes or so . I put a clear gas container on it off a lawn mower so i could monitor gas consumption and got the gps out. I dont want to run fast to much because this big prop is lugging my engine right now. My tiny tach is on the way too. It just seems to me this is an awful lot of gas .with not a lot of smoke (rich) no gas in the water its just kinda got me confused . This engine is what I thoughtwas almost perfect. I'm gonna pull the plugs tomorrow and see the result , may give me a clue. If you can help I'd sure appreciate it . thanks

 

[seahorse44]

Re: 1957 35hp rde-19c gas mileage

Rolmops,<br /> Thanks for the reply , how much gas does yours use say in ten miles running slow ? fast ? paul moir says they are worse at idle and midrange . I agree with you on the prop but I spun the hub out on my 10 3/8 X 12 . its sent off for a week. cant wait to get it back. I actually do have to open the throttle more at idle than I did with my old prop. Thanks ,,,give me something to think about.

 

[rolmops]

Re: 1957 35hp rde-19c gas mileage

OK,this may sound a bit far fetched,but a hub starts spinning for a reason.It spins because it gets worn down either by an underwater object that it hits or by being under constant overload which causes a lot of slippage in the water.By using the wrong pitch for your boat,a lot of gas gets burned up,especially when you accelerate.This is also when your slippage is very high and I suspect that this is where even the hub started spinning.Quite frankly I think that your pontoon boat is underpowered.Your seahorse has to work very hard to move it and a lot of gas goes to waste on slippage.According to the Michigan recommendations a 10 3/8x12 is for a 14 to 16 foot runabout. A barge propeller with lots of surface and a low pitch would be a very good idea.Your speed will not suffer and you will use your gas a lot more efficiently.My fuel consumption at 66% of wot(roughly 3300 rpm) is about 3 gallons per hour at 18 miles per hour.But it goes up dramatically with increased load.(Herter's boats have a poor hull design).<br />One more thing.If you went upstream your distnce relative to land may only have been 2 miles,but if the water runs against you at 3 miles per hour your movement would have been 5 miles relative to the water.

 

[seahorse44]

Re: 1957 35hp rde-19c gas mileage

rolmops,<br /> You bring up some good points. The creek was almost dead still. I spun my prop out by accident actually. I was against the bank and started the motor at full throttle while in forward gear. I was having trouble starting it before i fixed the crank seal. but after I repaired the lower crank seal she come to life and i didnt expect it. Mr. Moir straightened me out on that lower crank seal.<br /> I lied to Paul moir the other day about its speed too. It will run about 18 mph on gps (wot) with the 10 3/8 X 14 prop . rpm's unknown until My tiny tach comes. I agree with you on the prop size . i will be looking for a 10 1/2 X 11 ? Thanks,,,,,, sorry I'm so windy

 

[rolmops]

Re: 1957 35hp rde-19c gas mileage

Wait till you get some rpm readings.I know lots of happy seahorse owners who use 11x10.

 

[Paul Moir]

Re: 1957 35hp rde-19c gas mileage

18mph makes a lot more sense than 26mph. Probably the engine is only spinning somewhere between 3000-4000RPM at WOT then.

 

[seahorse44]

Re: 1957 35hp rde-19c gas mileage

Paul ,<br /> I imagine thats right Paul. I'm gonna try and find me a selection of props to try . Way I understand what your all saying is I'm lugging my engine even at idle. Makes sense . Your 35 use about the same gas as rolmops ? Thanks

 

[rolmops]

Re: 1957 35hp rde-19c gas mileage

I forgot to mention one thing.I do have a setup that recoups unburnt fuel.That saves a lot.Without it I would at best make 14 miles to 3 gallons.

 

[seahorse44]

Re: 1957 35hp rde-19c gas mileage

paul,rolmops,<br /> I ran mine again yesterday and at idle it started to miss some. I used sae 30 oil in my gas which I dont like to do(all I had) and think it fouled my plugs some. never again . I run champion j4c plugs I think . are these the correct plugs for this engine ? If not what is the right plug and gap. I will be idling a lot because of the no wake in the creek. Thanks

 

[Paul Moir]

Re: 1957 35hp rde-19c gas mileage

J4C gapped at .030" is the correct plug and gap. You might want to try a J6C if you do a lot of trolling, which is a hotter plug and is less prone to fouling. <br />If it's been a while, do a decarb. Check out the FAQ Forum for roscoe's instructions. Running 30 weight will build up deposits fast.<br /><br />Hope that helps!

 

[rwise]

Re: 1957 35hp rde-19c gas mileage

Mine gets better fuel mialage at 3/4 throtle than WOT. The carb doesn't start to open until then.<br />just a thought.

 

[rolmops]

Re: 1957 35hp rde-19c gas mileage

There is a very interesting thing with the length of the shaft on these engines.They have 2 cavitation plates.The bottom plate sits at 3 inches longer than standard.This makes the short shaft 18 inches and the long shaft 23 inches.You can save a lot of fuel and increase your speed by raising the engine those 3 inches on your transom plate.

 

[seahorse44]

Re: 1957 35hp rde-19c gas mileage

I have found the cure to get good mileage !! I took my boat out yesterday . It stops the temptation . I cant stand not to run it when it sits in the water. I'm weak . I appreciate all the help fellows. I'm sure this will be my homepage for years to come. <br /> I'm seriously thinkin about designing my own propulsion . there is some serious knowledge to be had here for a project like that . I have been a chief engineer on towboats for 23 years so I have some background in propulsion equip. soon I will post a picture of my 14' paddle wheeler just for enjoyment. thanks again !

 

[seahorse44]

Re: 1957 35hp rde-19c gas mileage

Paul Moir,<br /> I have been looking for a post on link-n-sync and have not had any luck. Heres what I did and maybe you can tell me If I'm right. I adjusted the butterfly to just start opening when On the mark. Then I loosened the little screw on the rod going to the timing plate , moved the timing plate to the stop(WOT) then adjusted the carb arm to hit the stop on the carb . I Liked your post on using the timing light and I will do this too.I'd really like to get it perfect. It runs great now. Plugs are both a little brown . mileage has improved greatly too. While I'm here have you ever had the packing on the needle valves leak and cause a little rough idle ? Thanks Paul .

 

[Paul Moir]

Re: 1957 35hp rde-19c gas mileage

Have a look here:<br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=033290#000006 <br />The adjustment is different though (second pic). You fish out a crecent wrench and loosen the screws holding the cam to the timing plate and move it in or out.<br />This explains the other link:<br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=28;t=033798#000007 <br /><br />Leaking packing will definitely cause a rough idle. You can get individual packing washers from the dealer for little money, or in a pinch I've used normal graphite & teflon packing from a home centre's plumbing supply section.<br /><br />Hope that helps!

 

[seahorse44]

Re: 1957 35hp rde-19c gas mileage

Paul Moir,<br /> Thanks for the reply. I must be a little thick headed or just dumb. I cant see a reason to move the cam on the timing plate. I think I have all that you require happening . just starts to move on the mark (I used the eccentric on the carb linkage to do this) timing plate going to the stop , the rod finishes up the last 1/4 of throttle. Before my timing plate was 1/4" shy of hitting the stop. so it was way off . Is it ok the way It is ? Many thanks for being patient.

 

[R. Bushie]

Re: 1957 35hp rde-19c gas mileage

I have a 1957 35 hp Evinrude and in reading this discussion I note that "rolmops" has mentioned he has incorporated "a setup to recuop unburnt fuel". Can this be explained? These old girls tend to be thirsty and an inovation such as "rolmops" would be great. Can this be discussed with maybe a diagram to aid understanding and construction? Thanks