"Jim Swope jr" wrote in message
et...
I just bought a 1971 Glastron V-170 Crestflite and it came with a 1983 75
horse Evinrude. The markings on the prop say 13-1/4X17.
The engine seems to be running fine at high and low rpm's.I cant hear any
missing. It cruises nicely at low rpm's but when I give it full throttle
It sounds like it is at full
throttle, im getting about 2500 rpms if I remember right. Also with the
cover off and manually holding the throttle at full bore I can only get
about
eight miles an hour out of it according to my hand held gps. At any rate
it goes pretty slow and Im not sure why. Is this engine too small for this
boat.
The recomendation for this boats says not to use any bigger than 125 horse
so Im thinking 75 should be sufficient.I've tried adjusting the plane in
all different positions but dosnt seem to matter much
and get no noticable increase in speed. Any suggestions would be happily
appreceiated.


A 75 hp motor should be fine with that boat. You've got problems with it
though. Could be any number of things, some of which others have suggested.
Hope you didn't pay much. And hope you're handy.

It could be a number of things but it doesn't sound expensive, just a tune-
up and maybe some ignition parts like condensor and or plugs or coils. The
coils aren't likely because it runs smoothly and not all three are going to
go at once. Solving yourself is a hassle but doable. First thing I'd check
is that the ignition advance lever is connected and adjusted properly - it
is a little bar that advances the spark when the throttle lever moves. Try
adjusting it one way and then the other to see what happens.

Are you sure that throttle is opening all the way? Sometimes the cable gets
a kink in it that prevents full movement - actually a few other parts can
prevent cable or throttle movement - check for something blocking full
travel. Could even be in the throttle box. Disconnect the cable from the
throttle bar and see if it moves farther.

Get a can of carb cleaner and run it through the carbs with engine running
- don't over do it so engine stalls. Modern gas has so many additives that
if there is old gas in the tanks or cabs they may be gummed up and you have
to take them apart and clean the whole mess - this is a lower probabilty
thing so check ignition and try cleaner first. If it was gummed up carbs it
shouldn't start at all and/or run rough.

The 17' pitch prop is a good pulling prop so it shouldn't be causing enfine
to bog down. If the hub was spun you would get lots of rpm and no go.

On Mon, 19 May 2008 18:22:15 GMT, Reno wrote:

Modern gas has so many additives that
if there is old gas in the tanks or cabs they may be gummed up and you have
to take them apart and clean the whole mess

On the contrary: modern gas has much less of a tendency toward gum
than a straight from the cracker and stills product.

They put additives in gas to, among other things slow the formation of
gum. They test for tendency to gum with a heated copper dish. I have
only one volumn of the ASTM standards. The one I have is on fuels and
I read it a while ago, I and I don't remember what all they said about
gum.

That said gum does exist. I have seen it in a garage sale lawn mower.
I have no idea how long it sat unused with perhaps years old gas in
it.

Fuel is among the most perishable of the things Army stocks. Ammo
lasts nearly forever, and food years longer than gasoline. They sell
an additive specifically to put in the fuel in your boat when you lay
it up for the winter. Never used it, never had any trouble in fifty
years.. Gum is a possibility but modern gas is really good in that
respect.

Casady