120-140 engine swap. Power not quite right.

[cedgo]

All parts from old block to new(used) block except distributor and carburetor. New block sat unused for several years. Idle good. Can not get full power. Feels as if the engine is starving for gas. Occasionally get a 3 to 4 second burst of full power then back to the "starving" issue.

Gas is fresh. Filters are new.
Questions. I know the carb on the 120 is good. Can I swap to the 140?
Any other thoughts on this problem?

Going to take the extra fuel pump along on the next outing if the carb swap doesn't work.

If the carb is at issue, what should I be looking for?

Hope this makes sense.

Again, thanks for the forum and all the excellent advice here!

 

[Bondo]

Re: 120-140 engine swap. Power not quite right.

All parts from old block to new(used) block except distributor and carburetor. New block sat unused for several years. Idle good. Can not get full power. Feels as if the engine is starving for gas. Occasionally get a 3 to 4 second burst of full power then back to the "starving" issue.

Gas is fresh. Filters are new.
Questions. I know the carb on the 120 is good. Can I swap to the 140?
Any other thoughts on this problem?

Going to take the extra fuel pump along on the next outing if the carb swap doesn't work.

If the carb is at issue, what should I be looking for?

Hope this makes sense.

Again, thanks for the forum and all the excellent advice here!

Ayuh,.... Rebuild the carb that's on it,...

We can't see the carbs,... You tell us whether they're the same or not,...

Merc has used a few...

 

[cedgo]

Re: 120-140 engine swap. Power not quite right.

Ayuh,...Thanks for the input there Bond-o. Carbs are identical as far as I can see. Manual says same carb for each engine, but books can be wrong, you guys are the experts. Switched 'em out this morning, will see what happens.

 

[Bondo]

Re: 120-140 engine swap. Power not quite right.

Ayuh,...Thanks for the input there Bond-o. Carbs are identical as far as I can see. Manual says same carb for each engine, but books can be wrong, you guys are the experts. Switched 'em out this morning, will see what happens.

Ayuh,... Good Luck with it,....

If it's still got an issue, a carb kit, 'n both carbs, Oughta be enough to build 1 Good 1,...

 

[Cptkid570]

Re: 120-140 engine swap. Power not quite right.

Are you sure it isn't a fuel pump issue? It idles fine when it doesn't need a lot of gas, then it sounds like it runs out of gas at higher speeds. You could put a glass in-line fuel filter in it temporarily (they sell them at auto parts stores and a lot of boat supply stores) and use that to make sure you are getting gas.

 

[cedgo]

Re: 120-140 engine swap. Power not quite right.

No Cptkid, I am not sure. Pump was good on old block, but it is 40 years old. Am going to pack the new pump on next trip to lake. I like doing just one thing at a time to help pinpoint any problem. Your idea sounds good, will stop at parts store. The more brains the better!
Thanks.

 

[cedgo]

Re: 120-140 engine swap. Power not quite right.

Dug this up to say, "Thanks for all the help."

Boat is now running like the proverbial scalded dog. The extra 20 horse sure does make a difference. Almost getting 4800 RPM at WOT.

 

[Eric 3.7LX Alpha 1]

Re: 120-140 engine swap. Power not quite right.

What was the problem?

 

[Bondo]

Re: 120-140 engine swap. Power not quite right.

Dug this up to say, "Thanks for all the help."

Boat is now running like the proverbial scalded dog. The extra 20 horse sure does make a difference. Almost getting 4800 RPM at WOT.

Ayuh,... Glad to hear ya got 'er fixed, but What was the problem,..??

 

[cedgo]

Re: 120-140 engine swap. Power not quite right.

Kinda embarrassed to admit. Had installed new plugs just to eliminate one factor. Thought maybe I had cracked one on installation. Well, another set confirmed a bad plug. Sometimes it's the simplest things....