technical stuff

fish 4 life · Oct 19, 2009

I have a 1978 Evinrude 140 HP on a 1985 Ranger 335-V Comanche that I am having trouble getting out of the hole. I had the carbs rebuilt and the mechanic says the engine runs like a top. I am able to get out of the hole but only if me and my brother sit at the front of the boat while my father drives. Once the boat does get on plane, the boat does about 45 mph and goes great. I was using a 13 X 19 3 blade prop I also tried a 13 X 17 4 blade prop and the same thing was happening. I was told I should check the engine for Link & Sync the carbs, Making sure the carbs are opening horizontal, and pickup timing is correct. Check timer base, that it is not sticking part way, has to go all the way to the rubber stop, check Max advance and set if needed. I am not sure what all this means. Can anyone explain this more so a non-mechanic like myself can understand.

tashasdaddy · Oct 19, 2009

Re: technical stuff

Tail heavy boat, check it for excessive weight, that vintage boat is known for having several hundred pounds of unwanted, unknown weight. saturated foam. there can be as much as 700 lbs of wet foam.

emdsapmgr · Oct 19, 2009

Re: technical stuff

Your mechanic/technician gave you some good ideas on things to check. Hard to explain any real detail on these short notes. Best to get a factory manual and compare the text with pictures-it's easier that way.

fish 4 life · Oct 19, 2009

Re: technical stuff

I had the boat shop drill some holes and found their was no water in the foam. Do you think the 16.83 foot boat is too small for the old and heavy 1978 motor.

noelm · Oct 19, 2009

Re: technical stuff

what is your max RPM? we need to know that, you may be way over propped.

fish 4 life · Oct 19, 2009

Re: technical stuff

The max RPMs I could get was at about 5400. I believe the max RPM that a 1978 140HP Evinrude is rated for about 5800.

kenmyfam · Oct 19, 2009

Re: technical stuff

How much motor is in the water ??? and how is the trim ???

fish 4 life · Oct 19, 2009

Re: technical stuff

I don't know exactly how much motor is in the water, but it seems like alot. The trim seems fine.

kenmyfam · Oct 19, 2009

Re: technical stuff

fish 4 life said:
I don't know exactly how much motor is in the water, but it seems like alot. The trim seems fine.

Power trim ???
How about a photo of the motor and boat showing how much is below the keel

fish 4 life · Oct 20, 2009

Re: technical stuff

Yes it has power trim. I will try to get some pictures as soon as possible.

wilde1j · Oct 20, 2009

Re: technical stuff

Cav plate should be dry @ WOT if engine height is right. If it's buried, come up one hole at a time until it's right. Once you get get that right, get RPM's up to 5800 @ WOT by reducing prop pitch. You tried a 17" four blade ... I would have tried a three blade or better a 15" pitch prop. But get the X dimension right first. This really sounds like a setup problem, not a motor problem. Do only one thing at a time, evaluate, and go on.

fish 4 life · Oct 20, 2009

Re: technical stuff

Attached is a picture of motor height.

fish 4 life · Oct 20, 2009

Re: technical stuff

Ranger boats said the same thing about using a 14 X 17 inch 3 blade aluminum prop. I might see if I can try to trade in my four blade for the 17 inch 3 blade aluminum prop. Also, the prop shop did say that they think my motor is to low and I should try to raise it a little.

wilde1j · Oct 20, 2009

Re: technical stuff

Can't tell much from the picture ... if the cav plate is buried in water at WOT, the motor needs to come up. All you can tell on dry land is whether the start point is somewhat reasonable, nothing more.

robert graham · Oct 20, 2009

Re: technical stuff

Sounds like your boat/motor/rig could use one of those hydro/foil wing type gizmos that you bolt right on to your cavitation plate to lift you up onto plane quicker. Boater's World and Cabela's sells many different models and prices, mostly a plastic wing. It would probably help you a lot. Good Luck!

wilde1j · Oct 20, 2009

Re: technical stuff

robert graham said:
Sounds like your boat/motor/rig could use one of those hydro/foil wing type gizmos that you bolt right on to your cavitation plate to lift you up onto plane quicker. Boater's World and Cabela's sells many different models and prices, mostly a plastic wing. It would probably help you a lot. Good Luck!

Those devices won't solve a rigging and/or a propping issue ... they do add drag and lower top speed, though.

emdsapmgr · Oct 20, 2009

Re: technical stuff

The height you have the engine currently mounted should not be the primary cause of poor holeshot. What are the compression numbers for each cylinder?

wilde1j · Oct 20, 2009

Re: technical stuff

I disagree. If motor is too deep, lots of drag. If propped with pitch too high, very sluggish hole shot. Both together, a dog of a boat, even if motor is running right.

fish 4 life · Oct 20, 2009

Re: technical stuff

emdsapmgr said:
The height you have the engine currently mounted should not be the primary cause of poor holeshot. What are the compression numbers for each cylinder?

I had the compression checked and all four cylinders are at 120 psi. Like I said the mechanic says the engine runs like a top. I can do 45+ mph when I can get the boat on plane.

kenmyfam · Oct 21, 2009

Re: technical stuff

How far in will it trim ???? (photo of that would help) if possible

technical stuff

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