1975 25 hp evinrude

[7173george]

Re: 1975 25 hp evinrude

went into my garage to check things out. there is no keel down the center.the drain plug pipe is dead center and sticks out 9/16".there are 2 keels on each side of center at 9". could the drain plug pipe be causing this spray of water? the spray coming up looks exactly the same as the video in the #2 reply to this post. The 2 keels are not squared off and stop about 1" before the back of the boat. this motor runs so good I would love to try to fix this issue.Do i need to make a pad about 12" wide to sort of square the bottom up.

 

[steelespike]

Re: 1975 25 hp evinrude

While it does have the old style gearecase the main water intake is on the front of the exhaust snout.
The intakes above the plate are to aid the pump at idle in neutral or reverse.
Chinewalker used to race with that style gearcase with no special provisions.
For whatever reason you may not get above the bottom but a reduction as little as a 1/4" could solve
the venting issues.
If your boat is light you could get around 30 mph with a little luck.
You should be able to rig up a simple jack plate that lets you fine tune the height.
In the old days they used to just lay 1/4" sticks on the transom to fine tune the height.
But that was on a setup that was allready close to the max.
I've seen a boat lose its ability to plane when a 1/4" stick was added.

 

[rscottmeyer]

Re: 1975 25 hp evinrude

If I'm really lucky, I might be able to find some "before and after" videos still on my computer. The spray was like that (in the #2 post), but probably not quite as extreme, and on the Riverhawk, it was the rounded "drain plug" chute that was causing it. My "pad" is probably only about 6" or 8" wide to keep the funnel from collapsing creating a pontoon boat style rooster tail catching the mid-section of the outboard(s), but I'll let you guys be the judge if I can get the video loaded up this week. Again, if there is any way to hang a camera over the transom while running, it will tell you a lot!

 

[7173george]

Re: 1975 25 hp evinrude

SUCCESS!!!! put some two part epoxy under the drain hole pipe.put some epoxy on tthe 2 keeks,she cruised down the lake, not a drop of water came over the transom. she ran at 23 mph. on my gps. i am a happy boater today.Thanks to everyone for your help.Now will a different prop make this boat go a little faster?it has a 9"x 10" on it.In my manual it says you could use a 9x9. what would this prop do?

 

[steelespike]

Re: 1975 25 hp evinrude

If your boat is a bare bones 1448 I think it should run closer to 30. Guessing at the slip your present rpm is about 4700
the motor is rated at a max of 6000. That would get about 29 on a light fast boat.
You should be able to get more than 23.It would be best to have a tach to get accurate rpm.
A tintach is reasonable and easy to install.

 

[7173george]

Re: 1975 25 hp evinrude

boat weighs 435,i'm 200 lbs partner 200, trolling motor, 2 batteries, console,baitwell,anchors> i'm guessing everything at 1200lbs. where do i find the tin tach? hauling this much wait do u think it should go faster?

 

[kfa4303]

Re: 1975 25 hp evinrude

Well that's quite a bit of weight. I think mid 20's might be more realistic at that load, but if you went out solo with very little gear you could probably get closer to 30 mph. Here's a link to the tiny tach site too. I've never used one, but lots of folks really like them and you don't have to do anything special to install them. You just wrap the lead around the spark plug wire and the gizmo is able to read the the rate at which the spark fires and therefore the rpms. Pretty clever. Good luck.

http://www.tinytach.com/tinytach/index.php

 

[steelespike]

Re: 1975 25 hp evinrude

Wow that is a load.Assuming 6% slip at 23mph with a 10" prop your turning about 4500 thats outside the recommended range.
I think the 9" will get you in range And with the motor in its power band you might gain a little speed.
Hole shot should be better and and the motor will be happier even if the speed ends up about the same.

 

[7173george]

Re: 1975 25 hp evinrude

ok thanks, i will try the 9x9.weather is getting cold again.next warm day i will give it a try and let you know how it works.

 

[oldman570]

Re: 1975 25 hp evinrude

With the load heavy like stated the best I get is around 26 mph and if I am in the boat alone with nothing extra I'll get around 30 MPH.I am running a Merc 1984 on a 1448 Starcraft Mod V with a 10X 13 cupped prop. That speed is plenty fast enought for me as the water gets might rough at times.
Oldman570

 

[7173george]

Re: 1975 25 hp evinrude

would a whale tail help me ouy at all?

 

[steelespike]

Re: 1975 25 hp evinrude

Whale tails can help but sometimes are a bandaid over a poor setup and can create there own problems.
As we discussed your motor it appears is at about 4500 rpm.
I doesn't develope its horse power till 5500 the closer you get to that the happier it will be.
The operation range is 5000-6000.
The 9" prop should help at least to get it to 5,000.

 

[ouachita22]

Re: 1975 25 hp evinrude

i was wondering if you've been able to correct this problem. i have a '75 with 135 HP. For the first time last week I had a large amount of water come in at the stern.

2 people in the boat and i had the boat running almost flat out. Then we look back and see all this water. plug was in.

During the rest of the day 6-7 hours on the water, no more water. Then went back to the dock at high speed, and see lots of water collected at the back!!

i have checked the stern for leaks at home. no leaks.

Any ideas? This seemed to be similar to the problem that you experienced.

Thanks,